Glossary of technical terms for the use of metallurgical engineers Terms starting with alphabet ‘M’
Glossary of technical terms for the use of metallurgical engineers
Terms starting with alphabet ‘M’
Macerate – It means to chop or shred fabric for use as a filler for a molding resin.
Machinability – It is the relative ease with which material is removed from a solid by controlled chip-forming in a machining process. It is the relative ease of machining a metal.
Machinability index – It is a relative measure of the machinability of an engineering material under specified standard conditions. It is also known as machinability rating.
Machine – It is a physical system which uses power to apply forces and control movement to perform an action. Machines can be driven by animals and people, by natural forces such as wind and water, and by chemical, thermal, or electrical power, and include a system of mechanisms which shape the actuator input to achieve a specific application of output forces and movement. They can also include computers and sensors which monitor performance and plan movement, frequently called mechanical systems. A simple machine is an elementary device which put a load into motion, and creates mechanical advantage which is the ratio of output force to input force. Modern machines are complex systems which consist of structural elements, mechanisms and control components and include interfaces for convenient use.
Machined springs – This type of spring is produced by machining a steel bar with a lathe and/or milling operation rather than coiling wire. Since it is machined, the spring may incorporate features in addition to the elastic element. Machined springs can be made in the typical load cases of compression / extension, and torsion etc.
Machine element – It refers to an elementary component of a machine. These elements consist of three basic types namely (i) structural components such as frame members, bearings, axles, splines, fasteners, seals, and lubricants, (ii) mechanisms which control movement in different ways such as gear trains, belts, or chain drives, linkages, cam and follower systems, including brakes and clutches, and (iii) control components such as buttons, switches, indicators, sensors, actuators and computer controllers. While normally not considered to be a machine element, the shape, texture and colour of covers are an important part of a machine which provide a styling and operational interface between the mechanical components of a machine and its users.
Machine forging – It is the forging which is performed in upsetters or horizontal forging machines.
Machine learning – It is the set of artificial intelligence techniques for systems which can follow examples to solve new problems.
Machine shop drawing – This drawing frequently gives only the information necessary for machining.
Machine shop turnings – This type of scrap constitutes clean steel or wrought iron turnings, free of iron borings, non-ferrous metals in a free-state, scale, or excessive oil. It cannot include badly rusted or corroded stock.
Machine vision – Machine vision has emerged as an important new technique for industrial inspection and quality control. When properly applied, machine vision can provide accurate and inexpensive inspection of workpieces, hence dramatically increasing product quality. Machine vision is also used as an in-process gauging tool for controlling the process and correcting trends which can lead to the production of defective parts. Some of the industries such as the automotive and electronics industries make heavy use of machine vision for automated high volume, labour intensive, and repetitive inspection operations. This ability to acquire an image, analyze it, and then make an appropriate decision is very useful in inspection and quality control applications. Machine vision enables it to be used for a variety of functions, including (i)identification of shapes, (ii) measurement of distances and ranges, (iii) gauging of sizes and dimensions, (iv) determining orientation of parts, (v) quantifying motion, and (vi) detecting surface shading. These capabilities allow users to employ machine vision systems for cost-effective and reliable 100 % inspection of workpieces.
Machine welding – It is welding with equipment which performs the welding operation under the constant observation and control of a welding operator. The equipment may or may not load and unload the work-piece.
Machining – It is removing material from a metal part, usually using a cutting tool, and normally using a power-driven machine.
Machining allowance – It is the quantity of excess metal surrounding the intended final configuration of a formed part which is sometimes called forging envelope, finish allowance, or cleanup allowance. It is also the quantity of stock left on the surface of a casting for machining.
Machining damage – It consists of irregularities or changes on the surface of a material because of the machining or grinding operations which can deleteriously affect the performance of the material / part.
Machining stress – It is the residual stress caused by machining.
Machining tears – Machining tears result from the use of machining tools having dull or chipped cutting edges. Such discontinuities serve as stress raisers and can lead to premature failure of a component especially when it is subjected to fatigue loading.
Mach number – It is a dimensionless quantity in fluid dynamics representing the ratio of flow velocity past a boundary to the local speed of sound, i.e., M= u/c where ‘M’ is the local Mach number, ‘u’ is the local flow velocity with respect to the boundaries (either internal, such as an object immersed in the flow, or external, like a channel), and ‘c’ is the speed of sound in the medium, which in air varies with the square root of the thermodynamic temperature. By definition, at Mach 1, the local flow velocity ‘u’ is equal to the speed of sound. At Mach 0.7, ‘u’ is 70 % of the speed of sound (sub-sonic), and, at Mach 1.45, ‘u’ is 45 % faster than the speed of sound (super-sonic). The local speed of sound, and hence the Mach number, depends on the temperature of the surrounding gas. The Mach number is mainly used to determine the approximation with which a flow can be treated as an incompressible flow. The medium can be a gas or a liquid.
Macro – In relation to composites, it denotes the gross properties of a composite as a structural element but does not consider the individual properties or identity of the constituents.
Macro-emulsions – Macro-emulsions (sometimes called as ‘soluble oils’) contain an oil-based lubricant, such as a mineral or compounded oil in the form of suspended droplets, which have been dispersed with the aid of special chemical agents called emulsifiers. The emulsified oil droplets are large enough to make the made up lubricant milky (or sometimes translucent) in appearance. The action of emulsions as lubricants can be close to that of the dispersed phase. Emulsions can also be formulated to include higher levels of extreme pressure agents or barrier films (polymers, and fats etc.) for heavy-duty operations. Macro-emulsions are usually milky white in appearance. They are normally used in heavy-duty metal working processes like roll forming of structural members, shelving, automotive, and furniture components.
Macro-etching– It means etching a metal surface to accentuate gross structural details, such as grain flow, segregation, porosity, or cracks, for observation by the unaided eye or at magnifications to 25×.
Macro-etch test – It is a test in which the sample is prepared with a fine finish and etched to give a clear definition of the weld.
Macro-etch testing – Soundness and homogeneity of alloy steel wire rods are sometimes evaluated macroscopically by examining a properly prepared cross section of the product after it has been immersed in a hot acid solution. It is customary to use hydrochloric acid for this purpose.
Macrograph – It is a graphic representation of the surface of a prepared sample at a magnification not exceeding 25×. When photographed, the reproduction is known as a photo macrograph.
Macro-hardness test – It is a term applied to such hardness testing procedures as the Rockwell or Brinell hardness tests to distinguish them from micro-indentation hardness tests such as the Knoop or Vickers hardness tests.
Macro-pore – It consists of pores in pressed or sintered compacts which are visible with the naked eye.
Macroscopic – It means visible at magnifications to 25×.
Macroscopic stress – It is the residual stress in a material in a distance comparable to the gauge length of strain measurement devices (as opposed to stresses within very small, specific regions, such as individual grains).
Macro-segregation – All metallic materials contain solute elements or impurities which are randomly distributed during solidification. The variable distribution of chemical composition on the macroscopic level is called macro-segregation. Since macro-segregations normally deteriorate the physical and chemical properties of materials, they are to be kept to a minimum.
Macro-shrinkage – It consists of isolated, clustered, or inter-connected voids in a casting which are detectable macroscopically. Such voids are normally associated with abrupt changes in section size and are caused by feeding that is insufficient to compensate for solidification shrinkage.
Macro-slip – It is a type of sliding in which all points on one side of the interface are moving relatively to those on the other side in a direction parallel to the interface. The term macro-slip is sometimes used to denote macro-slip velocity. However, this usage is not recommended.
Macro-strain – It is the mean strain over any finite gauge length of measurement large in comparison with inter-atomic distances. Macro-strain can be measured by several methods, including electrical-resistance strain gauges and mechanical or optical extensometers. Elastic macro-strain can be measured by X-ray diffraction.
Macro-structure – It is the structure of metals as revealed by macroscopic examination of the etched surface of a polished sample.
Mafic – It consists of igneous rocks composed mostly of dark, iron-rich and magnesium-rich minerals.
Magma – It is the molten material deep in the earth from which rocks are formed.
Magmatic segregation – It is an ore-forming process whereby valuable minerals are concentrated by settling out of a cooling magma.
Magmatogene deposits – The magmatogene deposits of iron ore are sub-divided into magmatic, contact-eta-metasomatic (or skarn deposit), and hydro-thermal deposits. Magmatic deposits include dike-shaped, irregular, and sheet-like titano-magnetite deposits associated with gabbro-pyroxenite rock, and apatite-magnetite deposits associated with syenites and syenite-diorites. Contact-metasomatic, or skarn, deposit form at contacts or near intrusive masses, surrounding carbonate and other type of rock which are changed by high temperature solutions into skarns, as well as scapolite and pyroxene-abilitic rock in which massive and impregnation magnetite ore deposits of complex shape remain separate. Hydro-thermal deposits form upon the action of hot mineralized solutions in cases of the deposition of iron ore in cracks and zones of crumpling, as well as in cases of metasomatic replacement of wall rocks.
Magnesia – It is a white hygroscopic solid mineral that occurs naturally as periclase and is a source of magnesium. It has an empirical formula of MgO and consists of a lattice of Mg2+ ions and O2- ions held together by ionic bonding. Magnesium hydroxide forms in the presence of water, but it can be reversed by heating it to remove moisture.
Magnesia-carbon (MgO-C) refractory – It is important and widely used refractory in the steelmaking. It is characterized by a reduced slag infiltration depth and a high thermal shock resistance due to its carbon content. Applications of this refractory not only include wear linings in basic oxygen furnace (BOF), electric arc furnace (EAF), and steel ladle, but also functional products such as purging and taphole bricks. The success of the use of basic magnesia-carbon refractory in the steelmaking is based on its good properties of resistance to erosion, corrosion, and thermal shock.
Magnesia-doloma (MgO-CaO) refractories – These refractories are composed of 50 % MgO to 80 % MgO. These refractories are produced in different ways. Because of these refractories showing a good chemical resistance against basic environments (as slag and fluxes) at high-temperature, good thermal shock resistance, low vapour pressure, thermodynamic stability in the presence of carbon, and a suitable abrasion resistance, magnesia-doloma refractories are widely used in ferrous, non-ferrous and cement industries. However, in spite of these advantageous properties, the application of these refractory bricks has not been popular because of their tendency to hydration when exposed to the atmosphere.
Magnesite – It refer to the naturally occurring magnesium carbonate mineral. In refractory terms it is used to refer to the high temperature product magnesia (periclase). There are three general grades of magnesite produced from natural magnesite (MgCO3) and magnesium hydroxide [Mg(OH)2] obtained from sea water or from brine deposits. These are dead burnt magnesite, seawater / brine magnesite, and fused magnesite. The three types of magnesite described above are used in a variety of refractory applications. Dead burnt magnesite is mostly used in the manufacture of basic monolithics such as gunning repair products, tundish working linings and precast shapes (tundish dams/weirs). Magnesia spinel bricks are produces with the addition of small amounts of alumina to improve thermal shock resistance. Fused magnesite tends to have superior properties to sintered magnesite and as such is incorporated into refractory products used in high wear areas such as slag lines etc.
Magnesite carbon bricks – These bricks contain 8 % to 30 % carbon. Bricks with carbon content 10 % to 20 % are more common. In magnesite carbon bricks, the high carbon content is achieved by adding flake graphite. The high oxidation resistance of flake graphite contributes to the reduced erosion rates of these bricks. In addition, the flake graphite results in very high thermal conductivities compared to most refractories. These high thermal conductivities are a factor in the excellent spalling resistance of the magnesite carbon bricks. By reducing the temperature gradient through a brick, the high thermal conductivities reduce the thermal stresses within the brick. High thermal conductivity also results in faster cooling of the brick between heats and thus reduces potential for oxidation. These days magnesite carbon bricks are made with good slag resistance and hot stability. A high degree of slag resistance and good high temperature stability have been found to be advantageous in the hotter and more corrosive service environments. High temperature stability of magnesite carbon bricks is achieved by utilization of high purity graphite and magnesite.
Magnesite chrome and chrome magnesite bricks – The reaction between chrome ore and magnesite outline the fundamental chemistry of the magnesite chrome bricks. Magnesite chrome bricks can be either silicate bonded or direct bonded. Silicate bonded bricks have a thin film of silicate minerals that surrounds and bonds together the magnesite and chrome ore particles. Direct bonded bricks have the direct attachment of the magnesia to the chrome ore without intervening films of silicate. Direct bonding is obtained by combining high purity chrome ores and magnesites and firing them at extremely high temperatures. Direct bonded bricks have high strength at elevated temperatures, better slag resistance and better resistance to peel spalling than silicate bonded bricks. The balance of properties of the bricks is a function of the magnesite to chrome ratio.
Magnesite refractories – Magnesite refractories are chemically basic refractories containing at least 85 % magnesium oxide. These refractories are one of the most widely used basic refractory bricks. They are manufactured either from natural occurring magnesite or sea water magnesia. Magnesite bricks are made from dead burnt magnesite. These bricks are strong and extremely durable. Their main advantage is very high slag resistance to basic slags specially lime and iron rich slags which is very important for steelmaking processes. Magnesite refractories have the properties of bearing high temperature, high refractoriness under load, and low vulnerability to attack by iron oxide and alkalis. Magnesite refractory bricks are widely used in the basic zone of metallurgical furnaces. These refractories have spalling resistance, strong abrasion and corrosion resistance, and high cold crushing strength. Physical properties of magnesite refractories are relatively poor. Magnesite bricks cannot resist thermal stock, loose strength at high temperature, and are not resistant to abrasion.
Magnesite spinel bricks – A family of magnesite spinel refractories has been developed by combining the constituent raw materials in different ways. Some magnesite spinel bricks are made by adding fine alumina to compositions composed mainly of magnesia. On firing, the fine alumina reacts with the fine magnesia in the matrix of the brick to form an in-situ spinel bond. An alternative is to add spinel grain to a composition containing magnesia. One of the principal benefits of combining spinel and magnesia is that the resulting compositions has better spalling resistance than bricks made solely with DBM. Spinel additions also lower the thermal expansion coefficient of magnesite compositions.
Magnesium -It is a chemical element. It has symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals, it occurs naturally only in combination with other elements and almost always has an oxidation state of +2. It reacts readily with air to form a thin passivation coating of magnesium oxide which inhibits further corrosion of the metal. The free metal burns with a brilliant-white light. The metal is obtained mainly by electrolysis of magnesium salts obtained from brine. It is less dense than aluminum and is used mainly as a component in strong and lightweight alloys which contain aluminum.
Magnesium aluminum silicate – It is a naturally occurring mineral obtained from silicate ores of the montmorillonite group. It is an emulsion stabilizer, thickening agent, and viscosity controller. It is a type of clay which is composed of magnesium, aluminum, and silicate minerals, and it is frequently referred to as smectite clay.
Magnesium aluminate spinel (MgAl2O4) – It is an important constituent of magnesia-based refractory materials. The melting point of magnesium aluminate spinel is 2,135 deg C. There are no natural deposits of MgAl2O4, which is, hence, normally obtained by reaction of mixtures of magnesium oxide and aluminium oxide. Commercial sintered magnesia–spinel refractory materials are divided into three categories namely magnesia rich, stoichiometric, and alumina rich.
Magnet – It is a material or object which produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, steel, nickel, and cobalt etc. and attracts or repels other magnets. A permanent magnet is an object made from a material which is magnetized and creates its own persistent magnetic field. Materials which can be magnetized, are also the ones which are strongly attracted to a magnet. These are called ferromagnetic (or ferrimagnetic). An electromagnet is made from a coil of wire that acts as a magnet when an electric current passes through it but stops being a magnet when the current stops. Frequently, the coil is wrapped around a core of ‘soft’ ferromagnetic material such as mild steel, which greatly enhances the magnetic field produced by the coil. The overall strength of a magnet is measured by its magnetic moment or, alternatively, the total magnetic flux it produces. The local strength of magnetism in a material is measured by its magnetization.
Magnet arc welding process – It is a pressure welding process with an arc that is moved magnetically under shielding gas. This technology can be used to join hollow sections with wall thicknesses of up to 10 millimeters. For example, this enables you to weld steel propshafts or torsion beams for axles. A prerequisite for this pressure welding process is that conductive and fusible materials are used and the components have tubular cross-sections. Magnet arc welding is suitable for wall thicknesses of 0.7 millimeters to 10 millimeters.
Magnetic alignment – It is an alignment of the electron-optical axis of the electron microscope so that the image rotates around a point in the centre of the viewing screen when the current flowing through a lens is varied.
Magnetic bearing – It is a type of bearing in which the force which separates the relatively moving surfaces is produced by a magnetic field.
Magnetic blowout – It is a component of a switching device which uses a magnetic field to assist in extinguishing the arc, using a permanent magnet or a coil.
Magnetic circuit – It is a path through which magnetic flux passes.
Magnetic constant – It is the constant which relates the strength of magnetic flux to magnetic induction in free space.
Magnetic contrast – In electron microscopy, it is the contrast which arises from the interaction of the electrons in the beam with the magnetic fields of individual magnetic domains in ferromagnetic materials. Special instrumentation is needed for this type of work.
Magnetic core – It is a magnetic component for high frequency electronic applications made from carbonyl iron powder or ferrite powder.
Magnetic core memory – It is a type of computer memory which stores data as magnetization in tiny rings of ferrite material.
Magnetic field – It is a physical field which describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet’s magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a non-uniform magnetic field exerts minuscule forces on ‘non-magnetic’ materials by three other magnetic effects namely paramagnetism, diamagnetism, and antiferromagnetism, although these forces are normally so small they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field can vary with location, it is described mathematically by a function assigning a vector to each point of space, called a vector field (more precisely, a pseudo-vector field).
Magnetic field testing – It consists of the tests which are intended to demonstrate the immunity of equipment when subjected to power frequency magnetic fields related to the specific locations and installation condition of the equipment (e.g. proximity of equipment to the disturbance source).
Magnetic flux – It is the magnetic field, A conductor which encloses a changing magnetic flux has a voltage induced in it.
Magnetic flux density – It is the quantity of magnetic field per unit area. It is measured in webers per square metre in SI (International System of Units) units.
Magnetic gradient survey – It is a geophysical survey using a pair of magnetometers a fixed distance apart, to measure the difference in the magnetic field with height above the ground.
Magnetic lens – It is a device for focusing an electron beam using a magnetic field.
Magnetic lifting devices – These devices are used for lifting and transporting of steel and ferrous metal stock or manufactured components. They are normally installed and used as single magnets or as arrangements of multiple magnets. In all of these cases, they are suspended from chains or wires or otherwise attached to the lifting equipment such as cranes. Electrically operated magnetic lifting devices are widely used in the iron and steel plants. Lifting magnets can be provided with no power supply, i.e., permanent magnets, or where power is supplied by cable from an external source or through an in-built battery. The magnet and any associated electrical equipment are to be designed for its intended purpose and constructed to withstand the environment in which it is required to operate. When used correctly magnetic lifting devices handle magnetic materials and components safely, and without the need for slingers.
Magnetic moment – It is the proportionality constant which relates the twisting torque produced on an object to the magnetic field.
Magnetic particle inspection – For alloy steel wire rod and wire products subject to magnetic-particle inspection, it is normal to test the product in a semi-finished form, such as billets (using samples properly machined from billets), to ensure that the heat conforms to the magnetic-particle inspection requirements, prior to further processing. The method of inspection consists of suitably magnetizing the steel and applying a prepared magnetic powder, either dry or suspended in a suitable liquid which adheres to the steel along lines of flux leakage. On properly magnetized steel, flux leakage develops along surface or sub-surface discontinuities. The results of the inspection vary with the degree of magnetization, the inspection procedure (including such conditions as relative location of surfaces tested), the method and sequence of magnetizing and applying the powder, and the interpretation.
Magnetic resonance – It is a phenomenon in which the magnetic spin systems of certain atoms absorb electromagnetic energy at specific (resonant) natural frequencies of the system.
Magnetic seal – It is a seal which uses magnetic material, instead of springs or bellows, to provide the closing force.
Magnetic separation – Magnetic separation technologies are used to take the advantage of the difference in the magnetic properties for separating iron ore from the non-magnetic associated gangue materials. It can be conducted in either a dry or wet environment, although wet systems are more common. It is used in several flow-sheets. Magnetic separation is typically used in the beneficiation of high-grade iron ores where the dominant iron minerals are ferro and para-magnetic. Wet and dry low-intensity magnetic separation techniques are used to process ores with strong magnetic properties such as magnetite while wet high-intensity magnetic separation is used to separate the Fe-bearing minerals with weak magnetic properties such as hematite from gangue minerals. Iron ores such as goethite and limonite are normally found in tailings and does not separate very well by either technique. A full range of magnetic separators is available, from low intensity drum separators to high gradient / high intensity separators, and for either wet or dry feeds. Separation is achieved by exploiting differences in the magnetic susceptibilities of the component minerals. There are five basic types of separators designed for exploiting differences in the magnetic properties from the simplest low intensity unit for separating magnetite to high intensity / gradient units for removing minor impurities. These are (i) wet and dry, low intensity magnetic separation (LIMS), (ii) high gradient magnetic separation (HGMS), (iii) wet high intensity magnetic separation (WHIMS), (iv) roll magnetic separators for processing weak magnetic ores, and (v) induction roll magnetic separation (IRMS) for concentrating dry ores.
Magnetic shielding – In electron microscopy, it is the shielding for the purpose of preventing extraneous magnetic fields from affecting the electron beam in the microscope.
Magnetic susceptibility – It is a measure of the degree to which a rock is attracted to a magnet.
Magnetic survey – It is a geophysical survey which measures the intensity of the earth’s magnetic field.
Magnetically hard alloy – It is a ferro-magnetic alloy capable of being magnetized permanently because of its ability to retain induced magnetization and magnetic poles after removal of externally applied fields, i.e., an alloy with high coercive force. The name is based on the fact that the quality of the early permanent magnets has been related to their hardness.
Magnetically soft alloy – It is a ferromagnetic alloy which becomes magnetized readily upon application of a field and which returns to practically a non-magnetic condition when the field is removed, i.e., an alloy with the properties of high magnetic permeability, low coercive force, and low magnetic hysteresis loss.
Magnetic-analysis inspection – It is a non-destructive method of inspection to determine the existence of variations in magnetic flux in ferro-magnetic materials of constant cross section, such as can be caused by discontinuities and variations in hardness. The variations are normally indicated by a change in pattern on an oscilloscope screen.
Magnetic bearings – A magnetic bearing is a bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear. Magnetic bearings support the highest speeds of all kinds of bearing and have no maximum relative speed. Passive magnetic bearings use permanent magnets and, hence, do not require any input power but are difficult to design. Techniques using diamagnetic materials are relatively undeveloped and strongly depend on material characteristics. As a result, majority of the magnetic bearings are active magnetic bearings, using electromagnets which require continuous power input and an active control system to keep the load stable. In a combined design, permanent magnets are often used to carry the static load and the active magnetic bearing is used when the levitated object deviates from its optimum position. Magnetic bearings typically require a back-up bearing in the case of power or control system failure. Magnetic bearings are used in several industrial applications such as electrical power generation, petroleum refinement, machine tool operation and natural gas handling.
Magnetic chip detector – It is an electronic instrument which attracts ferromagnetic particles (mostly iron chips). It is mainly used in aircraft engine oil and helicopter gearbox chip detection systems. Chip detectors can provide an early warning of an impending engine failure and thus greatly reduce the cost of an engine overhaul.
Magnetic field – It is a physical field which describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field. A permanent magnet’s magnetic field pulls on ferromagnetic materials such as iron, and attracts or repels other magnets. In addition, a non-uniform magnetic field exerts minuscule forces on non-magnetic materials by three other magnetic effects namely para-magnetism, dia-magnetism, and anti-ferro-magnetism, although these forces are normally so small that they can only be detected by laboratory equipment. Magnetic fields surround magnetized materials, electric currents, and electric fields varying in time. Since both strength and direction of a magnetic field may vary with location, it is described mathematically by a function assigning a vector to each point of space, called a vector field (more precisely, a pseudo-vector field).
Magnetic-particle inspection – It is a non-destructive method of inspection for determining the existence and extent of surface cracks and similar imperfections in ferro-magnetic materials. Finely divided magnetic particles, applied to the magnetized part, are attracted to and outline the pattern of any magnetic leakage fields created by discontinuities.
Magnetic particle testing – It uses one or more magnetic fields to locate surface and near-surface discontinuities in ferro-magnetic materials. It is used to locate surface and slight sub-surface discontinuities or defects in ferro-magnetic materials. Such flaws present in a magnetized part cause a magnetic field, i.e. flux, to leave the part. If magnetic particles are applied to this surface, they are held in place by the flux leakage to give a visual indication. While several different methods of magnetic particle tests can be used, they all rely on this same general principle. Hence, any magnetic particle test is conducted by creating a magnetic field in a part and applying the magnetic particles to the test surface. The magnetic field can be applied with a permanent magnet or an electro-magnet.
Magnetic pole – It is the region at each end of a magnet where the external magnetic field is strongest. A bar magnet suspended in earth’s magnetic field orients itself in a north-south direction. The north-seeking pole of such a magnet, or any similar pole, is called a north magnetic pole. The south-seeking pole, or any pole similar to it, is called a south magnetic pole. Unlike poles of different magnets attract each other while the like poles repel each other. Magnetic pole is the area on a magnetized part at which the magnetic field leaves or enters the part. It is a point of maximum attraction in a magnet
Magnetic separator – It is a device which is used to separate magnetic from less magnetic or non-magnetic materials. The crushed material is conveyed on a belt past a magnet.
Magnetic surveying – Magnetic survey measures variations in the earth’s magnetic field caused by magnetic properties of subsurface rock formations. The airborne magnetometer is the primary geological tool used in the search for iron ores and iron bearing materials in large areas. The method of conducting an airborne magnetic survey is to install a flux gate or proton precision magnetometer in an airplane which traverses the target area at a fixed altitude and along predetermined flight lines. The magnetometer measures the magnitude of the earth’s magnetic field. The data is recorded electronically along with the position of the airplane and its altitude. In recent years, there is improvements in the quality of the surveys due to the refinements in the equipment that include greater sensitivity and simplicity, multiple channel data recording, miniaturization of instruments and a more accurate positioning capability. Because of the presentation and recording of the data in digital form, computers are used for carrying out the necessary data reduction and plotting requirements needed for analyses and interpretation. Data from these records are plotted as a contour map, with lines connecting points of equal magnetic intensity on the map. The patterns formed by these lines indicate areas where magnetic anomalies (major local distortions of the earth’s magnetic field) occur. The areas indicated by anomalies on the magnetic map are then investigated in greater detail by geological surveys and by gravity measurements, electromagnetic studies or other geophysical techniques.
Magnetic thickness test – Non-destructive measurement of galvanized coatings is normally done with electronic instruments which measure the distance from the surface of the coating to the steel surface which is magnetic. Any non-magnetic coating over steel can be measured with these instruments.
Magnetic test – It is the method used to test heat extraction rates of various quenchants. The test works by utilizing the change in magnetic properties of metals at their Curie point (the temperature above which metals lose their magnetism).
Magnetism – It is the class of physical attributes which occur through a magnetic field, which allows objects to attract or repel each other. Because both electric currents and magnetic moments of elementary particles give rise to a magnetic field, magnetism is one of two aspects of electro-magnetism. The most familiar effects occur in ferro–magnetic materials, which are strongly attracted by magnetic fields can be magnetized to become permanent magnets, producing magnetic fields themselves. Demagnetizing a magnet is also possible. Only a few substances are ferro-magnetic. The most common ones are iron, cobalt, nickel, and their alloys.
Magnetite – It is black, magnetic iron ore, an iron oxide.
Magnetite ore – The main iron-bearing mineral of magnetite is tri-iron tetroxide, and its chemical formula is Fe3O4. The theoretical iron content is 72.36 %, the appearance colour is usually carbon black or slightly light blue black, metallic lustre, streaks (colour appearing on the board when the surface is uneven on the white porcelain plate) black. The most prominent feature of this ore is its magnetic nature, which is also the origin of its name. Magnetite contains both ferrous and ferric iron. It differs from most other iron oxides in that it contains both divalent and trivalent iron. It is generally very hard, dense in structure and poor in reducing performance. Generally, the hardness of magnetite is between 5.5 and 6.5 on Mohs scale, and the specific gravity is between 4.6 and 5.2.
Magnetization – It is a property of a material which measures its response to a magnetic field.
Magnetization current – In a transformer, it is that portion of the current which is used to support magnetic flux.
Magnetizing force – It is a force field, resulting from the flow of electric currents or from magnetized bodies, which produces magnetic induction.
Magneto-hydrodynamics (MHD) – It is also called magneto-fluid dynamics or hydro-magnetics. It is a model of electrically conducting fluids which treats all inter-penetrating particle species together as a single continuous medium.
Magneto-hydrodynamic lubrication – It is the hydrodynamic lubrication in which a considerable force contribution arises from electro-magnetic interaction. Magneto-hydrodynamic bearings have been proposed for very high-temperature operation, e.g., in liquid sodium.
Magneto-meter –Magneto-meters have passed through several successive stages of development. The principal forms as being known, in the order of their conception, are balance type, torsion type and flux gate magnetometers, followed in recent years by magneto-meters which have been conceived and developed in the field of atomic physics. These latter instruments include the rubidium vapour, proton-precession and optical absorption magneto-meters. Magneto-meters are used to determine the strength of the earth’s magnetic field or its vertical component at a given location. The earth’s field is very weak, ranging from about 0.7 oersted at magnetic poles to about 0.25 oersted at some points on the magnetic equator. In geomagnetic studies, field strength is measured in a much smaller unit than the oersted, which is the gamma (equal to 0.00001 oersted). The shape of the earth’s magnetic field is not uniform, but shows large scale regional irregularities due to variations in the shape and composition of the crust and upper mantle of the earth. Variations on a smaller scale result from magnetic disturbances caused by concentrations of magnetic material near the surface and it is these local variations that are sought when iron ores are searched.
Magneton – It is a unit of magnetic moment used for atomic, molecular, or nuclear magnets. The Bohr magneton (muB), which has the value of the classical magnetic moment (mu) of the electron, can theoretically be calculated as muB = mu0 = eh/2mc =9.2742 x 10 to the -2 erg/G = 9.2741 x 10 to the power -24 J/T, where ‘e’ and ‘m’ are the electronic charge and mass, respectively. ‘h’ is Planck’s constant divided by 2pi, and ‘c’ is the velocity of light.
Magneto-statics – It is the study of stationary magnetic fields.
Magneto-striction – It is the changes in dimensions of a body resulting from application of a magnetic field.
Magneto-strictive cavitation test device – It is a vibratory cavitation test device driven by a magneto-strictive transducer.
Magnet steels – These are normally alloy electrical steels. The outstanding property of these steels is their ability to retain magnetism. Cobalt, chromium, and tungsten are the alloying elements normally used to improve this characteristic.
Magnetron sputtering – It is a deposition technology involving a gaseous plasma which is generated and confined to a space containing the material to be deposited i.e., the ‘target’. The surface of the target is eroded by high-energy ions within the plasma, and the liberated atoms travel through the vacuum environment and deposit onto a substrate to form a thin film.
Magnet wire – It is the class of wire manufactured for winding electromagnetic coils such as in motors or transformers.
Magnification – It is the ratio of the length of a line in the image plane, e.g., ground glass or photographic plate, to the length of the same line in the object. Magnifications are normally expressed in linear terms and in units called diameters.
Magnifying transmitter – It is a concept for a signal transmitter which uses a resonant transformer to provide a high voltage.
Main bearing – It is a bearing supporting the main power-transmitting shaft.
Main distribution frame – In a telephone central office, It is the equipment which connects to subscriber circuits.
Mainframe computer – It is a large centralized computer system which is used for large volumes of data or supporting multiple interactive terminals, with large input / output capacity, normally expected to provide critical services to an organization with a predictable degree of reliability.
Mains electricity – It is the commercial electric power, purchased from an off-site source shared by several consumers. Regional supplies vary in voltage, frequency, and technical standards.
Mains hum – It is the interference on an audio or visual signal related to the power line frequency.
Main-spring – it is a spiral ribbon shaped spring used as a power source in watches, clocks, music boxes, wind-up toys, and mechanically powered flash lights.
Maintainability – In reliability theory, it means the measure of an item to be retained in, or restored to, a specified condition when maintenance is performed by personnel having specified skill levels and using prescribed procedures and resources, at each prescribed level of maintenance and repair.
Maintenance – It refers to supervising and preserving equipment and facilities used in industrial or manufacturing settings. It consists of servicing and repair of the equipment and facilities. It is the application of best practices to increase equipment up time of equipment and facilities. It includes scheduled and unscheduled maintenance. Maintenance can be scheduled as per the age of equipment or usage of equipment. Unscheduled maintenance can occur after equipment failure.
Maintenance activity – It consists of taking the decisions and actions regarding the upkeep of the plant, equipment, and facility. These are inclusive, but not limited to (i) actions focused on maintaining and analyzing the data related to the health of the plant, equipment, and facility, (ii) planning of adequate and necessary inventory of spare parts, lubricants, fast moving consumables, and storage items including standardization of spares and consumables, (iii) actions focused on scheduling, procedures, work / system control and optimization, and (iv) performance of routine, preventive, predictive, scheduled, and unscheduled actions aimed at preventing equipment failure as well as achieving the goal of increasing efficiency, reliability and safety. Further, besides the rectification of the faults in the equipment, the maintenance activities include (i) up-gradation of the existing plants and equipments and training maintenance personnel to attain the required technical skills, (ii) effective maintenance of the old equipment for higher availability, (iii) cost optimization of all maintenance functions, (iv) improvement of maintenance activities in the areas of tribology and terotechnology, (v) reconditioning of used / unserviceable spare parts, (vi) development of indigenous sources for parts for import substitution, (vii) setting up of an effective maintenance information management systems (MIMS), (viii) effective utilization of the maintenance personnel, and (ix) carrying out in-house research and development activities for effecting improvements in maintenance practices.
Maintenance information management systems (MIMS) – It refers to a type of software which organizations use to manage the maintenance activities in the organization. It includes day-to-day maintenance scheduling, planned maintenance and other maintenance practices, maintenance of equipment history, and inventory control for spare parts etc.
Maintenance practices – There are several types of maintenance practices which are being followed. These include planned maintenance, routine or reactive maintenance, preventive maintenance, predictive maintenance and reliability centered maintenance.
Maintenance schedule – It identifies the requirements and periodicities for regular and systematic examination, inspection, maintenance, and testing of all plant so that the plant operates normally, reliably, and safely.
Major injuries – This term is no more used internationally. The definition of the term varies widely from organization to organization. For example, length of absence can range from 45 days to 90 days, (ii) hospitalization, and (iii) medical definition either by own medical staff or by legislation.
Make-up water – Make up water is frequently needed in systems which use recirculating water. It is that water which is added to the system to compensate for the water (i) lost in the process, (ii) lost by the evaporation, and (iii) lost due to the leakages. In boiler, it is the water which is added to boiler feed to compensate for that lost through exhaust, blowdown, and leakage etc.
Male slip fit – In these pipe fittings there are no threads. They slip fit into a slightly larger diameter sleeve.
Male threaded – These pipe fittings have exterior threads. They are screwed into the inside of pipe end of a larger diameter with internal threading.
Malleability – It is the characteristic of metals which permits plastic deformation in compression without fracture.
Malleabilizing – It consist of annealing white iron in such a way that some or all of the combined carbon is transformed into graphite or, in some cases, so that part of the carbon is removed completely.
Malleable iron – It is a cast iron made by prolonged annealing of white iron in which decarburization, graphitization, or both take place to eliminate some or all of the cementite. The graphite is in the form of temper carbon. If decarburization is the predominant reaction, the product shows a light fracture surface, hence whiteheart malleable. Otherwise, the fracture surface is dark, hence blackheart malleable. Ferritic malleable has a predominantly ferritic matrix, while pearlitic malleable can contain pearlite, spheroidite, or tempered martensite, depending on heat treatment and desired hardness.
Malleable cast iron – It is cast as white cast iron, then ‘malleablized’ (i.e., heat treated to impart ductility to an otherwise brittle material). The micro structure consists of ferrite and particles of free graphite. This cast iron encompasses a form of graphite called temper carbon. This form of graphite is produced by the heat treatment of white cast iron. When a white cast iron is heated for an extended period of time (about 60 hours) at a temperature of 960 deg C, the cementite decomposes into austenite and graphite. By slow cooling from 960 deg C, the austenite transforms into ferrite or pearlite depending on the cooling rate and the diffusion rate of carbon. The ductility and toughness of malleable cast iron falls between that of ductile cast iron and gray cast iron. Now a days malleable cast irons have been replaced by the more economically produced ductile irons cast for many uses. Malleable cast irons besides ductility have good machinability. Ferritic malleable cast irons are more ductile and less strong and hard, than pearlitic malleable cast irons. Applications of malleable cast irons include parts of power train of vehicles, bearing caps, steering gear housings, agricultural equipment, and railroad equipment.
Management – It is a process which refers to a number of activities and functions. Management as an art refers to implementation, and management as a science refers to a systematic and scientific knowledge. As per these perspectives, different meanings are attributed to the concept of management. However, in its most general definition, management can be seen as a process directed to manage individuals and groups for a specific purpose. In other words, management is to ensure that the organization resources reach the goals by planning. Management can also be defined as the process of working with people and resources for the realization of organizational goals, for the coordination of the work with others or through others, efficiently, and effectively.
Management control – It an approach which enables the organization to produce desired results (normally expressed in terms of performance) by taking actions to achieve those results and by dealing with the dangers brought in by external difficulties (particularly those related to the market, competitors and the economic or political environment) and the internal difficulties of the organization. It consists of a systematic effort on the part of the organizational management. It is required to assure that all organizational resources are being used in the most effective and efficient manner possible in order to achieve the organizational objectives and goals. It constitutes (i) setting of performance standards with planning objectives, (ii) design of information feedback systems, (iii) comparison of actual performance with the predetermined standards, plans or objectives in order to determine whether there are any deviations and to measure their significance, and (iv) taking of any remedial action if needed.
Management information system (MIS) – It is a planned system for collecting, storing, and disseminating data in the form of information needed for carrying out different functions of the management. It provides information which the organization needs to manage itself efficiently and effectively. It deals with information related to technologies, processes, operation, human resource, commercial activities, and such other things within the organization and in its environment. Information means data which have been shaped into a form which is meaningful and useful to its users in the organization. Data, in contrast, are streams of raw facts representing organizational activities before they have been organized and arranged into a form which the management and other organizational users can understand and use. Management information system is a systematic organization and presentation of information which is normally needed by the organizational management for taking better decisions. It is an information system which integrates data from all the departments it serves and provides the management and the users with the information they need it is distinct from other information systems in that it is used to analyze and facilitate strategic and operational activities.
Management styles – Management styles constitute a broad concept which includes elements such as organization, planning, directing, coordination, control, procurement and selection, and authority sharing. The most important elements which bring the organization to success are the management style and the people. Management style expresses the way the managers use their authority over the employees and level of relationship with the employees in reaching the goals of the organization. Managers display one or more of the management styles. Some of the most commonly followed management styles are (i) authoritarian style which is also referred to as coercive style of management, (ii) authoritative style which is full of authority and influence, (iii) democratic style in which managers seek to achieve their objectives by consensus and employee participation, (iv) affiliative style which is closely related to the democratic style., (v) permissive style which is also referred to as Laissez-Faire style and in which the managers give little or no direction to the employees, (vi) indifferent style which is a bit similar to the permissive style, and in which managers just cannot be bothered, (vii) coaching style in which managers focus on training, guiding, counselling, and employee personal development for the future growth of the organization, (viii) pace-setting style in which managers set examples and standards for high performance, (ix ) visionary style in which managers move their employees to share positive dreams of the potential benefits and opportunities which they stand to gain, (x) bureaucratic style which is dominated by the procedure resulting the managers completely inflexible, (xi) defensive style which is practiced by managers who always seek to find fault from the employees and give the impression that they are correcting the fault, (xii) repulsive style which is characterized by the tendency of the manager to refuse being promoted to managerial positions and which extravagantly relies on the subordinates’ independence.
Management techniques – A large number of techniques are available to the management for the solving of the organizational issues. Selection of the proper techniques and then successful use of the selected techniques help the management to make the right decisions that leads to the effective and the efficient working of the organization. Right decisions taken at appropriate time not only enhances the processes, products and services of the organization but also propels the organization to deliver superior performance and profits. Successful use of such techniques requires an understanding of the strengths and weaknesses of each technique, as well as an ability to creatively integrate the right techniques, in the right way, at the right time. The secret is not in discovering one simple solution, but in learning which techniques to use, and how and when to use them.
Management techniques for entire organization – There are several management techniques which are not specific to one area of the organization. These techniques are rapidly becoming recognized as important keys for the organizational success. They normally cover several areas of the organization and some of them are very important management techniques. Management techniques which available for use of the entire organization are (i) vision and mission statements, (ii) bench marking, (iii) digitization process, (iv) core competencies, (v) complexity reduction, (vi) change management, (vii) contingencies planning, (viii) business process reengineering (BPE), (ix) management information system (MIS), (x) time management, (xi) continuous improvement process, (xii) crisis management, (xiii) creation of sustainable future, (xiv) decision making process, (xv) building organizational capabilities, (xvi) policy and strategy management, (xvii) creating problem solving culture, (xviii) harnessing of creativity and innovations, and (xix) disruptive innovation laboratories etc.
Management techniques for financial management – The main function of the financial management is to manage the finances of the organization. The functions include amongst others management of financial resources, management of receivables and expenditures and keeping proper accounts, management of cash flow, making timely payments, arrangement of finances for capital expenditure with minimum costs to the organization, and parking of savings for maximum yields etc. The management techniques available for the financial management include (i) budgeting, (ii) cost management (iii) auditing, (iv) risk analysis and management, (v) data analysis and management, (vi) contingency planning, (vii) resource management, and (viii) investors relation management etc.
Management techniques for human resource management – The main function of human resource management is to manage the personnel of the organization. The functions of the human resource management include amongst others human resource planning, recruitment of the employees, bringing the recruited employees on board, the talent enhancement of employees, deciding of the compensation, employees appraisals, handling of employees discipline, motivation of the employees, recognition and rewards, industrial relations, succession management, career planning, and welfare of employees etc. The management techniques available for the human resource management include (i) balanced scorecard, (ii) conflict management, (iii) delegation of power, (iv) compensation management, (v) employees’ engagement, (vi) employees’ satisfaction and satisfaction survey, (vii) development and implementation of effective communication system, (viii) industrial relation management, (ix) inter personal relationship, (x) maintenance of organizational discipline, (xi) planning for organizational learning, (xii) developing employees’ competencies, (xiii) tracking employees’ motivation (xiv) process approach to personnel management, (xv) talent management, (xvi) team working, (xvii) talent acquisition, (xviii) succession planning, (xix) outsourcing, (xx) employees’ loyalty management, and (xxi) people strategy for excellence etc.
Management techniques for managing organization future – Adoption to change and managing the future of the organization is important not only for the success of the organization but also for its survival. Management of the organization future is needed for meeting the organizational vision. It is needed either because of the external pressures or because of the internal reasons. It is needed either for consolidation or for expansion. It is also required for the enhancement of the organizational capabilities. Planning function of the management is deeply rooted in the management of the organization future. The management techniques used for the future planning of the organization includes (i) feasibility studies, (ii) creation of sustainable future, (iii) forward and backward integration, (iv) diversification strategies, (v) management of uncertainties, (vi) mergers and acquisitions, (vii) project evaluation and review technique, (viii) SWOT analysis, (ix) resource management and (x) risk management etc.
Management techniques for the management of safety, security and welfare – The health, safety and protection of employees, equipment and the environment are of serious concern in an organization. The health and safety of employees is crucial since it affects both economic and social factors. The organization also requires careful attention to security and safeguards. Security is aimed at preventing intentional acts that might harm the organization or result in the theft of materials. Employees’ welfare refers to those measures of the organization which aim at promoting the physical, psychological, and general wellbeing of the employees. The basic aim of welfare measures is to improve the living and working conditions of the employees along with their families. The management techniques available for the safety security and welfare in the organization are (i) development of occupational health and safety management system, (ii) safety audits, (iii) safety inspections, (iv) safe working procedures and work practices, (v) safety awareness and training, (vi) hazard, hazid, hazan, and hazop studies and analyses, (vii) risk management, (vii) safety consciousness, (vii) safety promotions, (viii) accidents / incident investigations and analyses, (ix) safety measurement and monitoring, (x) emergency preparedness, (xi) compliance to safety rules and regulations, (xii) use of personal protective equipments (PPEs), (xiii) stress and fatigue management at work place, (xiv) preventive security measures, (xv) protective security measures, (xvi) detective security measures, (xvii) punitive security measures, (xviii) security audits, (xix) use of security gadgets, (xx) intramural welfare facilities, and (xxi) extramural welfare facilities etc.
Management techniques for operational management – Functions of the operations in the organization are to manage various processes of the organization which produces products and services for the customers. These functions include production planning and control, operation of plant and equipment, maintenance and upkeep of the plant and equipment, optimization in the use of raw materials, conservation of materials and energy, maintenance of environment, and management of technological and workplace discipline etc. The management techniques for the operational management include (i) working with systems and procedures, (ii) development and implementation of management systems such as quality management system, environment management system, and energy management system, (iii) quality circles, (iv) value engineering, (v) suggestion scheme, (vi) quality assurance, (vii) process and quality control, (viii) management information system, (ix) knowledge management, (x) inventory management and control, (xi) data based decision making, (xii) adherence to technological discipline, (xiii) annual budgeting, (xiv) cost control, (xv) total quality management, (xvi) statistical quality control, (xvii) six sigma, (xviii) maintenance management system, (xix) process management, (xx) process automation, (xxi) performance management, (xxii) environmental, energy and technological audits, (xxiii) analytical thinking, (xxiv) failure analysis, (xxv) disaster management and contingency planning, and (xxvi) adoption of standardization techniques etc.
Management techniques for organizational functions involving external agencies – There are a number of organizational functions where the employees are to interact with outside agencies. Further the organization is to build and sustain its corporate image. Managing of the corporate image is the key to security and success of the organization and helps it in maintaining public trust. Major of the functions where the organizational employees come in contact with external agencies include sales and purchase functions, dealing with regulatory authorities and government, societal functions where the organization comes in touch with society, media and local authorities, and investors relations. Collectively the outside agencies are termed as stakeholders. Depending on the specific organization, stakeholders may include governmental agencies, statutory bodies, social activist groups, self-regulatory organizations, employees, shareholders, customers, suppliers, distributors, media and even the community in which the organization is located among many others. Management techniques available for organizational functions involving external agencies are (i) customer loyalty, (ii) customer segmentation, (iii) customer relationship management, (iv) customer focus, (v) customer satisfaction, (vi) customer centric approach, (vii) customer satisfaction survey, (viii) building of corporate image, (ix) branding, brand and brand management, (x) price optimization process, (xi) corporate social responsibilities, (xii) external communication, (xiii) supply chain management, (xiv) strategic alliances, (xv) involving stakeholders in the decision making processes, (xvi) development of purchase and sales procedures, (xvii) contract management, (xviii) developing negotiating skills, (xix) building of confidentiality and transparency, and (xx) investors relationship management etc.
Managerial control process – It is a process which is broadly defined as an operation that uses resources to transform inputs into outputs. It is the resource which provides the needed energy to the process for the transformation to occur. In an organization there are two types of processes. The first type of processes are those processes which create, produce, and deliver products and services while the second type of processes are those processes which do not produce outputs bur are still necessary in the functioning of the organization. The first group of the processes can be called work processes while the second type of the processes can be called administrative processes. Both the types of the processes are important for the functioning of the organization and need adequate process control activities for their successful implementation.
Mandrel – It is a blunt-ended tool or rod used to retain the cavity in a hollow metal product during working. It is a metal bar around which other metal may be cast, bent, formed, or shaped. It is also a shaft or bar for holding work to be machined. It is also a form, such as a mould or matrix which is used as a cathode in electroforming. In piling, mandrel is a full-length steel core set inside a thin-shell casing. It increases the structural capacity of the casing so that it can be driven. It helps in maintaining pile alignment and prevents the casing from collapsing. It is removed after driving is completed and prior to placing reinforced concrete. In case of composites it is the core tool around which resin-impregnated paper, fabric, or fiber is wound to form pipes, tubes, or structural shell shapes.
Mandrel forging – It is the process of rolling or forging a hollow blank over a mandrel to produce a weldless, seamless ring or tube.
Manganese – It is a chemical element. It has symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, frequently found in minerals in combination with iron. It is a transition metal with a multifaceted array of industrial alloy uses. It improves strength, workability, and resistance to wear. Manganese fulfils a variety of functions in steel. It is used as a deoxidizing agent in nearly all steels. It forms manganese sulphide inclusions which are spherical in the cast product. In the absence of manganese, sulphur inter-dendritic films of iron sulphide causing brittleness at hot working temperature (hot shortness). It effectively increases hardenability and up to 1.5 % and hence it is added for this purpose. In larger amounts, it is used to stabilize austenite, as in 14 % manganese steel. Manganese is normally present in all steel and functions as a deoxidizer. It also imparts strength and has responsiveness to heat treatment. It is normally present in quantities of 0.5 % to 2 %. In the range 0.3 % to 1.5 %, it is always present in steels to reduce the negative effects of impurities carried out forward from the production process e.g. sulphur embrittlement. It promotes the formation of stable carbides in quenched-hardened steels. Alloy steels containing manganese are pearlitic. Up to 1 %, it acts as hardening agent and from 1 % to 2 % improves strength and toughness. Alloy steels containing more than 5 % are non-magnetic. Alloy steels containing large proportions of up to 12.5 % manganese have the property that they spontaneously form hard skins when subject to abrasion (self-hardening properties). All commercial steels contain 0.3 % to 0.8 % manganese, to reduce oxides and to counteract the harmful influence of iron sulphide.
Manganese bronze – It is a frequently, but incorrectly, used term to describe the duplex, high tensile brasses which contain manganese.
Manhole – It is the opening in a pressure vessel of sufficient size to permit a man to enter.
Man-hours per ton (M-h/t) – It is a measure of labour efficiency of a steel plant. It is the ratio of total hours worked by steel plant employees to the tons shipped for a given period of time. Changes in the inventory level and work which is contracted out affects the reported measurement.
Manifold – It is system of pipes and valves for using a group of gas cylinders, or boil-off from vacuum insulated evaporators, to feed a single supply line. The advantages of the manifold system as compared with using a single cylinder are increased capacity and reliability, and also the possibility of a centralized supply for multiple users. The two main design aspects are use of a banks of cylinder connected in parallel and switch-over among different banks. By drawing from more than one cylinder simultaneously, a higher total quantity of gas is available, which means the system does not need to have the cylinders replaced very frequently. The number of cylinders connected at a time can be varied, and a large supply can be provided while still using reasonably small cylinders. It is also a pipe or header for collection of a fluid from, or the distribution of a fluid to a number of pipes or tubes.
Manipulated variable (MV) – It is the quantity in a process which is adjusted or otherwise manipulated in order to influence the PV. It is also used to describe the output signal generated by a controller; i.e. the signal commanding (manipulating) the final control element to influence the process.
Manipulators – They are used for rotating the rolled stock at a specific angle around its longitudinal axis.
Man-made (synthetic) diamond – It is a manufactured diamond, darker, blockier, and considered to be more friable than majority of the natural diamonds.
Mannesmann process – It is a process for piercing tube billets in making seamless tubing. The billet is rotated between two heavy rolls mounted at an angle and is forced over a fixed mandrel.
Manual actuators – These actuators are normally used for overrides of power actuators described above. This is an important safety measure in case the power actuator fails. Manual actuators typically consist of either a lever or a wheel (used for larger valves) connected to a screw or thread which turns the valve.
Manual and automatic instruments – Manual instrument needs the services of an operator, where as in automatic instruments there is no need for an operator. As an example, measurement of rotational speed by a hand operated tachometer an operator is needed to make the contact of the instrument with the rotating shaft. For measurement of temperature by a resistance thermometer by wheat-stone bridge in its circuit an operator is required to indicate the temperature being measured. On the other hand, in measurement of temperature by mercury-in-glass thermometer, no operator is needed.
Manual cooling bed – It has slope for the bar to move forward by sliding action due to gravity. Mechanical cooling beds are rake-type. Several types of mechanical cooling beds are used. The rolled bar as it enters the cooling bed slides onto the first notch on the rakes. The initial notches provide continuous support for the bar on a casting called a grid casting. Long plates with notches set at some distance apart, support the bar after it moves beyond the grid castings. The bar moves across the cooling bed by the movement of alternative plates moving in a cycle of lift, move, and retract, by the action of eccentric cams. Repeating of this cycle moves the bars as they are delivered from the mill. The length of the cooling bed is determined by the maximum run-out bar length, optimized by the selling lengths to minimize crop losses. The width of a cooling bed is determined on the basis of mill productivity (tons/hour) and the time required for cooling.
Manual gas shut-off valve – It is a manually operated valve in a gas line for the purpose of completely turning on or shutting off the gas supply.
Manual hoist – A hand chain hoist is a type of manual hoist powered by a hand chain to lift or lower the load. It is a manual hoist which is a force multiplier. It gives a workman the ability to lift very large loads (up to 50 ton) with ease by using mechanical advantage. Most hand hoists are used for infrequent maintenance applications where speed is not a requirement. They are considerably less expensive than powered hoists, but they require physical effort (pulling of the hand chain) to lift the load. They are not fast and are not generally specified for continuous lifting applications, especially when long lifts are required. Manual hoists can be trolley mounted. Trolleys can be of several different configurations. The most common are the hand powered (plain or push type). Also, trolleys can be hand geared (hand chain driven) and motorized (electric or air powered).
Manual metal arc welding (MMAW) process – It is also known as shielded metal arc welding (SMAW) process or flux shielded arc welding (FSAW) process. It is normally called stick, or covered electrode welding. It is a manual welding process whereby an arc is generated between a flux-covered consumable electrode and the work piece. The process uses the decomposition of the flux covering to generate a shielding gas and to provide fluxing elements to protect the molten weld-metal droplets and the weld pool. In the manual metal arc welding process, the arc is initiated by momentarily touching or ‘scratching’ the electrode on the base metal. The resulting arc melts both the base metal and the tip of the welding electrode forming a pool of molten metal (weld pool) which cools to form a joint. The molten electrode metal / flux is transferred across the arc (by arc forces) to the base-metal pool, where it becomes the weld deposit covered by the protective, less-dense slag from the electrode covering. As the weld is laid, the flux coating of the electrode disintegrates, giving off vapours which serve as a shielding gas and providing a layer of slag, both of which protect the weld area from atmospheric contamination. The metal arc welding process is the most widely used welding process. It is the simplest, in terms of equipment requirements, but it is, perhaps, the most difficult in terms of welder training and skill-level requirements.
Manual mode – Manual mode is when the controller’s decision-making ability is by-passed to let a human operator directly determines the output signal sent to the final control element.
Manual press – Different types of manual presses exist for the densification of the materials. Some come in the form of piston or screw presses but are operated with bare hands and hardly uses electricity. Manual press is designed for the purpose of briquette making or adapted from existing implements used for other purposes. Manual clay brick making press is a good example with which briquettes can be made from the feedstock. The manual press is made from both metal and wood with the latter being the most common. These machines operate with very minimal pressure. Binder addition to the feedstock is needed. Manual presses are characterized by low capital costs, low operating costs, and low levels of skill needed to operate the machine. However, it has a low production capacity of around 5 kilograms per hour to 50 kilograms per hour.
Manual welding – It is a welding operation which is performed and controlled completely by hand.
Manufacturer drawing – Manufacturing drawing shows all the detailed dimensions and specifications of a single part so that it can be made with precision. Manufacturing drawing includes complete dimensions, the surface finish, welding information, plating, and any other requirements such as the deburring of the part. The quantities and complexity of the part influences how the manufacturer decides which method is the most cost effective to produce it.
Manufacturing – It is the conversion of materials into finished parts, products, and goods which have value to end-users. Manufacturing involves the design, development, implementation, control, operation, and maintenance of processes which facilitate and perform the conversion of starting materials into finished products having higher value.
Manufacturing cost estimation– It is the collection of methodologies and tools used to forecast the expected final cost of a manufactured product. Manufacturing cost is the sum of costs of all resources consumed in the process of making a product. The manufacturing cost is classified into five categories namely direct materials cost, energy cost, consumables cost, direct labour cost, and manufacturing overhead.
Manufacturing engineering – It is also known as production engineering. It is a branch of engineering which shares several common concepts and ideas with other branches of engineering such as mechanical, chemical, electrical, and industrial engineering. Manufacturing engineering needs the ability to plan the practices of manufacturing, to research and to develop tools, processes, machines, and equipment; and to integrate the facilities and systems for producing quality products with the optimum expenditure of capital. The manufacturing engineer’s main focus is to turn raw material into an updated or new product in the most effective, efficient, and economic way possible.
Manufacturing flexibility – It is the ease with which a process can be adapted to produce different products or variations of the same product. Process flexibility is influenced greatly by the time to set up or change tooling.
Manufacturing lead time – It is the time needed to process the product through the manufacturing plant. It is related to the process cycle time.
Manufacturing processes – The term manufacturing processes represents the main shape-generating methods such as casting, moulding, and forming processes, as well as traditional and non-traditional machining processes. These processes can be classified into three groups of processes namely (i) casting moulding, (ii) material removal, and (iii) forming. This classification provides a guide for the selection of the manufacturing processes which can be suitable contenders for a component. In majority of the cases, there are several processes which can be used for a component and final selection depends on a large number of factors, mainly associated with a range of technical capabilities and process economics, not the least component size, geometry, tolerances, surface finish, capital equipment, and labour costs. Some of the main process selection drivers are (i) product quantity, (ii) equipment costs, (iii) tooling costs, (iv) processing time, (v) labour intensity and work patterns, (vi) process supervision, (vii) maintenance, (viii) energy consumption, (ix) overhead costs, (x) material costs and availability, (xi) material to process compatibility, (xii) component form and dimensions, (xiii) tolerance requirements, (xiv) surface finish requirements, (xv) bulk treatment and surface engineering, (xvi) process to component variability. (xvii) process waste, and (xviii) component recycling. These drivers are not necessarily of equal importance or do not occur in a fixed sequence.
Mapping document – It is the output of a comparison between another resource classification system and United Nations Framework Classification (UNFC), or between that system and existing ‘Aligned systems’, which highlights the similarities and differences between the systems. A Mapping document can provide the basis for assessing the potential for the other system to become an Aligned system through the development of a Bridging document.
Map-staking – It is a form of claim-staking practiced in some jurisdictions whereby claims are staked by drawing lines around the claim-on-claim maps at a government office.
Maraging – It is a precipitation-hardening treatment applied to a special group of high-nickel iron-base alloys (maraging steels) to precipitate one or more intermetallic compounds in a matrix of essentially carbon-free martensite.
Maraging steels – These steels are high nickel steels with not less than 18 % nickel and are characterized by extreme high strength and toughness. Nickel normally encourages the formation of austenite in steels as opposed to carbides. Because of this, under the proper conditions high strength can be obtained by the transformation of austenite into martensitic type structures. The advantage of maraging steels is that this change is achieved as a result of a simple heat treatment which means that the problems of distortion normally associated with high temperature heat treatments are avoided. A typical heat treatment can involve heating to 820 deg C grade followed by air cooling (This avoids distortion which is associated with a faster rate cooling). The process is completed by ageing at a temperature in the range 450 deg C to 510 deg C.
Marble – It is a metamorphic rock which is derived from the recrystallization of limestone under intense heat and pressure.
Marforming process – It is a rubber-pad forming process developed to form wrinkle-free shrink flanges and deep-drawn shells. It differs from the Guerin process in that the sheet metal blank is clamped between the rubber pad and the blank-holder before forming begins.
Margin – It is the difference between the cost of an item and the price at which it is sold. The aim, hence, of the majority of the organizations is to make as much profit margin as possible while ensuring prices stay competitive. There is no denying that pricing is crucially important.
Marginal deposit – It is an ore-body of minimal profitability.
Marginal economic resources – Marginal economic resources are resources which at the time of determination are not economic, but border on being so. They can become economic in the near future as a result of changes in technological, economic, environmental and / or other relevant conditions.
Marginal stability – It is said of a system which neither returns to its initial state when disturbed nor diverges to some unstable condition.
Margin of safety – It is that margin which is built into the safety analyses of the facility as set forth in the authorization basis acceptance limits. It is the margin needed in order to ensure safety. In engineering, the margin of safety is the factor of safety (strength of the material divided by the anticipated stress) minus one. It is something which is over and above what is strictly necessary and which is designed to provide for emergencies. It is a spare quantity or measure or degree allowed or given for contingencies or special situations. Margin of safety is also defined by the range between two conditions identified in a hazard control document such as the technical safety requirements. The first is the most adverse condition estimated or calculated in safety analyses to occur from an operational upset or family of related upsets. The second condition is the worst‐case value known to be safe, from an engineering perspective. This value is expected to be related to the condition at which some accident prevention or mitigation action is taken in response to the upset or accident, not the actual predicted failure point of some component.
Marine corrosion – It includes the deterioration of structures and vessels immersed in seawater, the corrosion of machinery and piping systems which use seawater for cooling and other industrial purposes, and corrosion in marine atmospheres. Although salt water is normally considered to be a corrosive environment, it is not widely understood how corrosive salt water is in comparison to other environments, such as fresh (salt-free) water. When studying the corrosion rate of iron in aqueous (NaCl) solutions of different concentrations, it can be seen that the maximum corrosion rate occurs near 3.5 % sodium chloride concentration which is the approximate salt concentration of seawater. Further, there are other variables in seawater and in the marine environment which affect corrosion rates in different ways. Also, different corrosion behaviours are there for specific metals and alloys in the marine environment. The general marine environment includes a great diversity of sub-environments, such as full-strength open ocean water, coastal seawater, brackish and estuarine waters, bottom sediments, and marine atmospheres. Exposure of structural materials to these environments can be continuous or intermittent, depending on the application. Structures in shallow coastal or estuarine waters are frequently exposed simultaneously to five zones of corrosion. Beginning with the marine atmosphere, the structure then passes down through the splash, tidal, continuously submerged (or subtidal), and subsoil (or mud) zones. The relative corrosion rates frequently experienced on a steel structure passing through all of these zones are different.
Marine energy – It consists of useful energy from tides, waves, or salinity or temperature gradients of the ocean which can be extracted.
Mark – It is the damage in the surface of the product whose name is frequently described by source.
Mark, arbor – It is surface damage in the vicinity of a coil inside diameter caused by contact with a roughened, damaged, or non-circular arbor.
Mark, bearing – It is a depression in the extruded surface caused by a change in bearing length in the extrusion die.
Mark, bit – It is a line which is normally perpendicular to the rolling direction.
Mark, bristle – It is raised surface around 25 millimeters long, crimped wire shaped, and oriented in any direction.
Mark, carbon – It is gray or black surface marking caused by contact with carbon run-out blocks.
Mark, chatter (roll or leveler) – It is numerous intermittent lines or grooves which are normally full width and perpendicular to the rolling or extrusion direction.
Mark, drag – It is a surface area showing a scratch or abrasion resulting from contact of the hot extrusion with the press equipment or tooling or, in the case of multi-hole dies, with other sections as they exit the press.
Mark, edge follower – It is faint intermittent marks at the edge of a cold rolled product, which are normally perpendicular to the rolling direction. This mark is caused by action of devices designed to rewind coils without weave.
Market – It is the marketplace where the sale of organizational products and services is carried out.
Marketing – It is a key management discipline which ensures the organization (producer of goods and services) to interpret consumer desires and match, or exceed them. The marketing process is central to the performance of the organization, since it addresses the most important aspects of the market. It is about understanding the competitive market-place and ensures the organization to tap into key trends, to reach the customers with the right product at the right price, place, and time. Efficient marketing has led several organizations to success. Marketing refers to the organizations use to integrate their products or services with the wants or needs of a customer. Product marketing represents the intersection of the product, marketing, and sales teams to bring awareness to a product and how it can provide value to a customer.
Market analysis – In a feasibility re[ort , market analysis is done to check the demand and supplies of the steel products included in the product mix in order to find the gap between demand and supplies. The positive gap between demand and supplies provides assurance that the product mix of the plant has got good demand and their marketability is not of a concern when the plant is commissioned.
Marketing management – It is an organizational discipline which focuses on the practical application of marketing techniques and the management of marketing resources and activities of the organization. It is the management of the marketing activities in the organization and includes management of the processes of planning, organizing, directing, motivating, coordinating, and controlling. It is the process of satisfying the needs and wants of the customers of the organization. It is an important function of the organization since it brings the organization closer to its customers and consists of establishing a marketing orientated organization where the emphasis is on the customer. It is a core component in the success of the organization.
Market order – It is an order to buy or sell at the best price available. In absence of any specified price or limit, an order is considered to be ‘at the market’.
Mark, handling – For rolled products, it an area of broken surface which is introduced after processing. The mark normally has no relationship to the rolling direction. For extrusions, it is the damage which can be imparted to the surface during handling operations.
Mark, heat treat contact – It is brownish, iridescent, irregularly shaped stain with a slight abrasion located somewhere within the boundary of the stain. It is a result of metal-to-metal contact during the quenching of solution heat treated flat sheet or plate.
Mark, inclusion – It is the appearance of surface where actual inclusion or the void it left is observed.
Markings, product – These are marks and symbols which provide a unique and quick identifier for a product. Markings consists of a special symbol, word, or picture which the organization uses for the product identification.
Mark, knife – It is a continuous scratch (which also can be creased) near a slit edge, caused by sheet contacting the slitter knife.
Mark, knock-out – It is a small solid protrusion or circular fin on a forging or a casting, resulting from the depression of a knock-out pin under pressure or inflow of metal between the knock-out pin and the die or mould.
Mark, leveler chatter – It is numerous intermittent lines or grooves which are normally full width and perpendicular to the rolling or extrusion direction.
Mark, metal-on-roll – For rolled products, it is a sharply defined surface impression on the metal which can be caused by a blow from another object. For extrusions, it is a synonym for handling mark.
Mark, mike – It is a narrow continuous line near the rolled edge caused by a contacting micro-meter.
Mark, pinch – It is a sharp deviation from flat in the sheet which is transferred from processing equipment subsequent to the roll bite.
Mark, roll – For rolled products, it is a small repeating raised or depressed area caused by the opposite condition on a roll. The repeat distance is a function of the offending roll diameter. For extrusions, it is a longitudinal groove or indentation caused by pressure from contour rolls as a profile (shape) passes through them for dimensional correction.
Mark, roll bruise – It is a greatly enlarged roll mark with a very shallow height or depth.
Mark, roll skid – It is a full-width line perpendicular to the rolling direction and repeating as a function of a work roll diameter.
Mark, rub – It is a large number of very fine scratches or abrasions. A rub mark can occur by metal-to-metal contact, movement in handling, and movement in transit.
Mark, snap – It is a band-like pattern around the full perimeter of an extruded section and perpendicular to its length. A snap mark can occur whenever there is an abrupt change in the extrusion process.
Mark, stop – It is a band-like pattern around the full perimeter of an extruded section and perpendicular to its length. A stop mark occurs whenever the extrusion process is suspended.
Mark, stretcher jaw – It is a cross-hatched appearance left by jaws at the end(s) of metal which has been stretched. These marks are seen if insufficient metal has been removed after the stretching operation.
Mark, tab – It is a bend, crease, wrinkle, or departure from flat, occurring perpendicular to the slit edge of a coil and which are repetitive in nature, with severity decreasing as the distance increases in the coil
from the original source. Normally, it is found on the inside diameter of a coil but can appear on the coil outside diameter as a result of a prior winding operation.
Mark, tail – It is a greatly enlarged roll mark with a very shallow height or depth.
Mark, take-up – It is a short longitudinal indentation parallel to the rolling direction.
Mark, traffic – It is the abrasion which results from relative movement between contacting metal surfaces during handling and transit. A dark colour from the abrasively produced aluminum oxide is normally observed in case of aluminum metal. A mirror image of a traffic mark is observed on the adjacent contacting surface.
Mark, whip – It is a surface abrasion which is normally diagonal to the rolling direction. It is caused by a fluttering action of the metal as it enters the rolling mill.
Marquenching – It is a hardening procedure in which an austenitized ferrous material is quenched into an appropriate medium at a temperature just above the martensite start temperature of the material, and held in the medium until the temperature is uniform throughout, although not long enough for bainite to form, then cooled in air. The treatment is frequently followed by tempering. When the process is applied to carburized material, the controlling martensite start temperature is that of the case. This variation of the process is frequently called marquenching.
Martempering – It is a hardening process in which an austenitized ferrous material is quenched into an appropriate medium at a temperature just above the martensite start temperature of the material, held in the medium until the temperature is uniform throughout, although not long enough for bainite to form, then cooled in air. The treatment is frequently followed by tempering. When the process is applied to carburized material, the controlling martensite start temperature is that of the case. This variation of the process is frequently called marquenching.
Martensite – It is a generic term for micro-structures formed by diffusion-less phase transformation in which the parent and product phases have a specific crystallographic relationship. Martensite is characterized by an acicular pattern in the micro=structure in both ferrous and non-ferrous alloys. In alloys where the solute atoms occupy interstitial positions in the martensitic lattice (such as carbon in iron), the structure is hard and highly strained, but where the solute atoms occupy substitutional positions (such as nickel in iron), the martensite is soft and ductile. The quantity of high-temperature phase which transforms to martensite on cooling depends to a large extent on the lowest temperature attained, there being a rather distinct beginning temperature (Ms) and a temperature at which the transformation is essentially complete (Mf).
Martensite range – It is the interval between the martensite start (Ms) and the martensite finish (Mf) temperatures.
Martensitic – It is a platelike constituent having an appearance and a mechanism of formation similar to that of martensite.
Martensitic stainless steels – These are essentially alloys of chromium and carbon which possess a distorted body-centered cubic (bcc) crystal structure (martensitic) in the hardened condition. They are ferro-magnetic, hardenable by heat treatments, and are normally resistant to corrosion only to relatively mild environments. Chromium content is normally in the range of 10.5 % to 18 %, and carbon content can exceed 1.2 %. The chromium and carbon contents are balanced to ensure a martensitic structure after hardening. Excess carbides can be present to increase wear resistance or to maintain cutting edges, as in the case of knife blades. Elements such as niobium, silicon, tungsten, and vanadium can be added to modify the tempering response after hardening. Small quantities of nickel can be added to improve corrosion resistance in some media and to improve toughness. Sulphur or selenium is added to some grades to improve machinability.
Martensitic steels – To create martensitic steels, the austenite which exists during hot rolling or annealing is transformed almost entirely to martensite during quenching on the runout table or in the cooling section of the continuous annealing line. The martensitic steels are characterized by a martensitic matrix containing small amounts of ferrite and / or bainite. Within the group of multi-phase steels, martensitic steels show the highest tensile strength level. This structure can also be developed with post forming heat treatment. Martensitic steels provide the highest strengths, up to 1,700 MPa ultimate tensile strength. Martensitic steels are frequently subjected to post quench tempering to improve ductility, and can provide adequate formability even at extremely high strengths.
Martensitic transformation – It is a reaction which takes place in some metals on cooling, with the formation of an acicular structure called martensite.
Marx generator – It is a kind of circuit for generating very high direct current voltage pulses.
Maser – It is a device which produces microwave energy in a similar manner to a laser.
Mask – In thermal spraying, mask is a device for protecting a surface from the effects of blasting and / or coating or adherence of a spray deposit. Masks are normally either reusable or disposable.
Masking –This is the process of using a material to produce intentionally ungalvanized areas, typically used in areas which are to be welded, on faying surfaces, or areas where the galvanized coating is not necessary for uniform corrosion protection.
Mass absorption coefficient – It is the linear absorption coefficient divided by the density of the medium.
Mass balance, material balance – It is an application of conservation of mass. By accounting for material entering and leaving a system, mass flows can be identified which are otherwise unknown, or difficult to measure without this technique. The exact conservation law used in the analysis of the system depends on the context of the problem, but all revolve around mass conservation, i.e., that the matter cannot destroyed or be created spontaneously.
Mass concentration – In a slurry, it is the mass of solid particles per unit mass of mixture, expressed in percent.
Mass-conserving process – It is a manufacturing process in which the mass of the starting material is approximately equal to the mass of the final product or part. Examples are casting, precision forming, and powder processes.
Mass density – It is the mass per unit of volume of the material.
Mass density (or density) of the steam – It is the specific mass of the steam in a volume of 1 cubic metre.
Mass finishing – It normally involves loading components to be finished into a container together with some abrasive media, water, and compound. Action is applied to the container to cause the media to rub against the surfaces, edges, and corners of the components, or for components to rub against each other, or both. This action can deburr, generate edge and corner radii, clean the parts by removing rust and scale, and modify the surface stress. The basic mass finishing processes include (i) barrel finishing, (ii) vibratory finishing, (iii) centrifugal disc finishing, (iv) centrifugal barrel finishing, (v) spindle finishing, and (vi) drag finishing. Mass finishing is a simple and low-cost means of deburring and surface conditioning components. Consistent results from part to part and batch to batch are normally ensured. All metals and several non-metals in a variety of sizes and shapes can be handled. Processes range from heavy radiusing and grinding operations to very fine finishing. A basic advantage of mass finishing is that the action is effective on all the surface edges and corners of the part. Normally, preferential treatment to one area is impossible. Action is greater on corners than other similarly exposed surfaces. Action in holes and recesses is less than on exposed areas.
Massive sulphide – It is relatively dense, fine grained, sometimes bedded, sulphide mineralization, normally lens-shaped and stratiform, i.e., restricted to a particular geologic horizon
Mass number – It is the number of protons plus neutrons in the nucleus of an atom.
Mass production – It is a system of production where products are produced at large scale on continuous basis. Production is done in anticipation of market demand, not on the basis of specific order of the customer.
Mass-reducing process – It is a manufacturing process in which the mass of the starting material is higher than the mass of the final product or part, and forming takes place by the removal of material, e.g., machining.
Mass spectrometer – It is an apparatus for measuring the masses of isotopes, molecules, and molecular fragments by ionizing them and determining their trajectories in electric and magnetic fields.
Mass spectrometry – It is an analytical technique for identification of chemical structures, analysis of mixtures, and quantitative elemental analysis, based on application of the mass spectrometer. This analytical technique is used to measure the mass-to-charge ratio of ions. The results are presented as a mass spectrum, a plot of intensity as a function of the mass-to-charge ratio.
Mass spectrum – It is a record, graph, or table which shows the relative number of ions of different masses which are produced when a given substance is processed in a mass spectrometer. It is a type of plot of the ion signal as a function of the mass-to-charge ratio. These spectra are used to determine the elemental or isotopic signature of a sample, the masses of particles and of molecules, and to elucidate the chemical identity or structure of molecules and other chemical compounds.
Mass-to-charge ratio (m/Q) – It is a physical quantity relating the mass (quantity of matter) and the electric charge of a given particle, expressed in units of kilograms per coulomb (kg/C). It is most widely used in the electro-dynamics of charged particles, e.g. in electron optics and ion optics. The importance of the mass-to-charge ratio, as per the classical electro-dynamics, is that two particles with the same mass-to-charge ratio move in the same path in a vacuum, when subjected to the same electric and magnetic fields.
Mass transfer – It is the net movement of mass from one location (normally meaning stream, phase, fraction, or component) to another. Mass transfer occurs in several processes, such as absorption, evaporation, drying, precipitation, membrane filtration, and distillation. Mass transfer is used by different scientific disciplines for different processes and mechanisms. The phrase is normally used in engineering for physical processes which involve diffusive and convective transport of chemical species within physical systems.
Master alloy – It is an alloy, rich in one or more desired addition elements, which are added to a metal melt to raise the percentage of a desired constituent.
Master alloy powder – It is a pre-alloyed metal powder of high concentration of alloy content, designed to be diluted when mixed with a base powder to produce the desired composition.
Master block – It is a forging die block used mainly to hold insert dies.
Master encoder – In rolling mill shears, it is the incremental encoder connected to the stand motor and is used to detect the material position.
Master pattern – In foundry practice, it is a pattern embodying a double contraction allowance in its construction. It is used for making castings to be used as patterns in production work.
Master product model – It is an approach toward design in which the product design is centred on an information-rich computer model which supports not only the physical design, but analysis, testing, design, optimization, simulation, prototyping, manufacturing, and maintenance.
Mat – It is a fibrous material for reinforced plastic consisting of randomly oriented chopped filaments, short fibres (with or without a carrier fabric), or swirled filaments loosely held together with a binder. It is available in blankets of different widths, weights, and lengths. It is also a sheet formed by filament winding a single-hoop ply of fibre on a mandrel, cutting across its width and laying out a flat sheet.
Match – It is a condition in which a point in one metal-forming or forging die half is aligned properly with the corresponding point in the opposite die half within specified tolerance.
Matched edges – It consists of two edges of the die face which are machined exactly at 90-degree to each other, and from which all dimensions are taken in laying out the die impression and aligning the dies in the forging equipment.
Matched metal moulding – It is a reinforced plastics manufacturing process in which matching male and female metal moulds are used (similar to compression moulding) to form the part, with time, pressure, and heat.
Matched set drawing – It defines items which are matched and for which replacement as a matched set is essential. It is prepared when the required dimensions, tolerances, or other characteristics of items can only be specified in terms of the matched relationship. This includes items which are inter-changeable only as a set because of special requirements for machining, electrical characteristics, performance, etc. It includes (i) physical or functional mating characteristics of the matched items (set), (ii) unique identifier assigned to each of the parts and to the matched set, and (iii) discrete identification marking of the matched set.
Match plate – It is a plate of metal or other material on which patterns for metal casting are mounted (or formed as an integral part) to facilitate moulding. The pattern is divided along its parting plane by the plate.
Matching draft – It is the adjustment of draft angles (normally involving an increase) on parts with asymmetrical ribs and sidewalls to make the surfaces of a forging meet at the parting line.
Material characterization – It is the use of different analytical methods (spectroscopy, microscopy, and chromatography etc.) to describe those features of composition (both bulk and surface) and structure (including defects) of a material which are significant for a particular preparation, study of properties, or use. Test methods which yield information mainly related to materials properties, such as thermal, electrical, and mechanical properties, are excluded from this definition.
Material flow diagram – It is also known as material flow chart. It is used to visualize the use of materials. e.g. along a supply chain. It is used to show material and mass flows in a visually appealing way. Hence, it can show e.g., the distribution of goods or the consumption of resources within a production system. Also, it is applicable for holistic material flow analyses. It can cover a large number of areas such as (i) material flow analysis and management, (ii) supply chain management, (iii) plant planning, (iv) process engineering, and (v) logistics. Several times, it is visualized by so called Sankey diagram where flow widths proportional to the flow quantity. Material flow diagram provides a lot of benefits for the visualization of material usages.
Material handling – It is a system designed for the storage and retrieval of materials in manufacturing and distribution.
Material handling system – It utilizes manual, semi-automated, and automated equipment to assist the movement and storage of materials within the system. Material handling system equipments are grouped into four main categories named storage and handling equipments, bulk material handling equipments, mobile equipments and industrial trucks, and engineered systems.
Material hardness – It is the property of the material which enables it to resist plastic deformation, usually by penetration or by indentation. The term of hardness is also referred to stiffness or temper, or to resistance to bending, scratching, abrasion, or cutting. It is the property of a material, which gives it the ability to resist being permanently, deformed when a load is applied. The higher is the hardness of the material, the higher is the resistance it has to deformation.
Materiality – It needs that a public report contains all the relevant information which investors and their professional advisers reasonably need, and reasonably expect to find in the report, for the purpose of making a reasoned and balanced judgement regarding the Exploration results, Mineral resources or Ore reserves being reported. Where relevant information is not supplied an explanation is to be provided to justify its exclusion.
Material models – Material models quantify physical material properties, that is, the ability of the material to respond to physical influences.
Material modelling environment – It contains multi-disciplinary sub-models integrated into the life cycle system boundary, consisting of materials processing and manufacturing.
Materials performance index – It is a combination of materials properties formulated in such a way that the largest value of the index designates the best material for the application.
Material property – It is an intensive property of a material, i.e., a physical property or chemical property which does not depend on the quantity of the material. These quantitative properties can be used as a metric by which the benefits of one material against another can be compared, hence helping in materials selection.
Material removal rate (MRR) – It is the quantity of material removed per time unit (normally per minute) when performing machining operations such as using a lathe or milling machine. The more material removed per minute, the higher the material removal rate. The material removal rate is a single number that enables an operator to do this. It is a direct indicator of how efficiently the operator is cutting, and how profitable the operator is. Material removal rate is the volume of material removed per minute. The higher are cutting parameters, the higher is the material removal rate. In grinding, it is the volume of material removed in a unit of time. Material removal rate = work speed × depth of cut × width of cut.
Material requirements planning (MRP) system – It is a production planning, scheduling, and inventory system used to manage manufacturing processes. Majority of the material requirements planning systems are software-based, but it is possible to conduct material requirements planning manually as well. A material requirements planning system is intended to simultaneously meet three objectives namely (i) ensure raw materials are available for production and products are available for delivery to customers, (ii) maintain the lowest possible material and product levels in store, and (iii) plan manufacturing activities, delivery schedules and purchasing activities.
Material safety data sheet (MSDS) – It is a form which contains detailed information about the possible safety and health hazards of a product and how to safely store, use, and handle the product. In several countries, suppliers are required to provide material safety data sheets for all hazardous materials as a condition of sale.
Material selection – It is a step in the process of designing any physical object. In the context of product design, the main goal of material selection is to minimize cost while meeting product performance goals. Systematic selection of the best material for a given application begins with properties and costs of candidate materials. Material selection is frequently benefited by the use of material index or performance index relevant to the desired material properties.
Material substitution – It is a class of material selection problem where a design already exists and the task is to replace the existing material with a more suitable one.
Material utilization – It is the percentage of the material processed that ends up in the product. A high material utilization means high product yield and near-net shape processing.
Materials engineering – It is an engineering discipline of finding uses for materials in different fields and industries.
Materials processing – It consists of the series of steps or ‘unit operations’ used in the manufacture of raw-materials into finished goods. The operations involve a succession of industrial processes with different mechanical or chemical procedures, normally produced in large quantities or batches.
Materials science – It is an interdisciplinary field of studying and discovering materials.
Meteorology – It is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting.
Mathematical model – It is an abstract description of a concrete system using mathematical concepts and language. The process of developing a mathematical model is termed mathematical modeling. Mathematical models are used in process control and engineering disciplines.
Matmor process – It is an iron making process which is based on lignite coal. It is a process with a design consisting of a simple, low cost, low emission, and Matmor retort using cheaper, alternative raw materials. This technology comprises two exclusive features namely (i) it uses lignite coal as a reductant and heat source which is not claimed as of now by any other technology, and (ii) it includes in its plant design, a vertical shaft furnace which works with the natural chemistry of the lignite coal. The process is based upon the removal of moisture by Coldry technology and the harnessing of the natural chemistry of the lignite coal through a process and a vertical retort furnace whose design and process chemistry is different to those of a blast furnace. The process chemistry of the Matmor process utilizes hydrogen as a reducing gas, enabling lower operating temperatures and shorter process times than countered in the iron making by blast furnace.
Matrix – It is the continuous or principal phase in which another constituent is dispersed. It is also the principal element or elements in a sample. Ion composites, matrix is the essentially homogeneous material in which the fibre system or reinforcing particles of a composite are embedded. Both thermo-plastic and thermo-set resins can be used, as well as metals, ceramics, and glasses.
Matrix chart – It is a type of flow chart in which the activities in a process are shown under the department carrying it out.
Matrix isolation – It is a technique for maintaining molecules at low temperature for spectroscopic study. This method is particularly well suited for preserving reactive species in a solid, inert environment.
Matrix metal – It is the continuous phase of a polyphase alloy or mechanical mixture. It is the physically continuous metallic constituent in which separate particles of another constituent are embedded.
Matte – It is an intermediate product of smelting. It is an impure metallic sulphide mixture made by melting a roasted sulphide ore, such as an ore of copper, lead, or nickel. Matte is to be refined further to get pure metal. In galvanizing, matte is dull, lacking or deprived of shine. Matte gray galvanized appearance can result from steel chemistry or can be intentionally induced when the use of the galvanized steel defines reflectivity limits.
Matte finish – It is a dull texture produced by rolling sheet or strip between rolls that have been roughened by blasting. It is a dull finish characteristic of some electrodeposits, such as cadmium or tin.
Matter – It is a substance which has mass and takes up space by having volume.
Maximum – The maximum is the highest value in a numerical variable. In the variable with the values 12, 15, 11, 18, 13, 14, 18 then 18 is the maximum value.
Maximum allowable working pressure (MAWP) – It is the maximum gauge pressure permissible in a completed boiler. The MAWP of the completed boiler is to be less than or equal to the lowest design pressure determined for any of its parts. This pressure is based upon either proof tests or calculations for every pressure part of the boiler using nominal thickness exclusive of allowances for corrosion and thickness needed for loadings other than pressure. It is the basis for the pressure setting of the pressure relieving devices protecting the boiler.
Maximum continuous load – It is the maximum load which can be maintained for a specified period.
Maximum daily limit (MDL) – It is the total maximum daily load. It is the absolute maximum allowable load or concentration of a substance in a facility’s effluent. This limit can be based on water quality constraints, sector-specific technology limits, or case-specific technology considerations. The value is typically calculated based on the 99th percentile of existing or required performance.
Maximum erosion rate – It is the maximum instantaneous erosion rate in a test which shows such a maximum followed by decreasing erosion rates. Occurrence of such a maximum is typical of several cavitation and liquid impingement tests. In some examples, it occurs as an instantaneous maximum, in others it occurs as a steady-state maximum which persists for some time.
Maximum instantaneous demand – It is the sudden load demand on a boiler beyond which an unbalanced condition can be established in the boiler’s internal flow pattern and / or surface release conditions.
Maximum likelihood estimation (MLE) – It is a method of estimating the parameters of an assumed probability distribution, given some observed data. This is achieved by maximizing a likelihood function so that, under the assumed statistical model, the observed data is most probable. The point in the parameter space which maximizes the likelihood function is called the maximum likelihood estimate. The logic of maximum likelihood is both intuitive and flexible, and as such the method has become a dominant means of statistical inference. Maximum likelihood estimation is a means of estimating the coefficients of a statistical model which relies on finding the coefficient values that maximize the likelihood function for the collection of study endpoints in the sample.
Maximum likelihood method – It is a method of parameter estimation in which a parameter is estimated by the value of the parameter which maximizes the likelihood function. In other words, the maximum likelihood estimator is the value of theta which maximizes the probability of the observed sample. The method can also be used for the simultaneous estimation of several parameters, such as regression parameters. Estimates obtained using this method are called maximum likelihood estimates.
Maximum load (Pmax) – It is the load which is having the highest algebraic value in the load cycle. Tensile loads are considered positive and compressive loads negative. The term is also used to determine the strength of a structural member i.e., the load which can be borne before failure is apparent.
Maximum pore size – It is the maximum pore opening of a porous material, such as a filter, through which no large particle passes.
Maximum prospective short-circuit current – It is the calculated value of current which can flow if a short circuit occurred. It is a parameter for selection of circuit protection devices.
Maximum rate period – In cavitation and liquid impingement erosion, it is a stage following the acceleration period, during which the erosion rate remains constant (or nearly so) at its maximum value.
Maximum strength – It is the maximum stress (tensile, compressive, or shear) which a material can sustain without fracture. It is determined by dividing maximum load by the original cross-sectional area of the sample. It is also known as the ultimate strength.
Maximum stress (Smax) – It is the stress having the highest algebraic value in the stress cycle, tensile stress being considered positive and compressive stress negative. The nominal stress is used most commonly.
Maximum stress intensity factor (Kmax) – It is the maximum value of the stress-intensity factor in a fatigue cycle.
Maxwell’s equations – These are the fundamental relations between electric and magnetic fields, expressed in concise mathematical form.
McQuaid-Ehn grain size -It is the austenitic grain size developed in steels by carburizing at 927 deg C followed by slow cooling. Eight standard McQuaid-Ehn grain sizes rate the structure, from number 8 which is the finest, to number 1 which is the coarsest. The use of standardized methods for determining grain size is desired.
Mean – It is an important statistic tool which measures the central tendency of a set of data. It is a measure of the ‘middle’, sometimes called the ‘average’. It is that value of a variate such that the sum of deviations from it is zero, and hence it is the sum of a set of values divided by their number.
Mean coefficient of linear thermal expansion – It is the ratio of the change in length to the original length at a reference temperature, ‘T0’, per degree of temperature change, where ‘T0’ is normally room temperature. If ‘L0’ is the length at ‘T0’ and alpha (a) is the mean coefficient of linear thermal expansion, the length at temperature ‘T1’ (Lt), is given by the equation Lt = L0[1 + a(T1-T0)].
Mean deviation – The mean deviation is a measure of spread. The mean deviation is an average (mean) difference from the mean. The value it gives is similar, but slightly smaller than the standard deviation. Although it is intuitively simpler than the standard deviation it is used less. The reason is largely since the standard deviation is used in inference, because the population standard deviation is one of the parameters of the normal distribution.
Mean diameter – It is the average of two measurements of the diameter at right angles to each other.
Mean duration rate – It is the total number of days lost divided by the total number of accidents during the period.
Mean effective pressure (MEP) – It is a quantity relating to the operation of a reciprocating engine and is a measure of an engine’s capacity to do work which is independent of engine displacement. In spite ot having the dimension of pressure, mean effective pressure cannot be measured. When quoted as an indicated mean effective pressure (IMEP), it can be thought of as the average pressure acting on a piston during the different portions of its cycle. When friction losses are subtracted from the indicated mean effective pressure, the result is the brake mean effective pressure (BMEP).
Mean free path – It is the average distance over which a moving particle (such as an atom, a molecule, or a photon) travels before substantially changing its direction or energy (or, in a specific context, other properties), typically as a result of one or more successive collisions with other particles.
Means of escape – It is the structural means whereby a safe route is provided for persons to travel unaided from any point in a building to a place of safety.
Mean of a variable – It is the arithmetic average of the variable’s values.
Mean square error (MSE) – For unbiased estimators, the mean square error is an estimate of the population variance. For biased estimators, the mean squared deviation of an estimator from the true value is equal to the variance plus the squared bias. The square root of the mean square error is referred to as the root mean square error.
Mean stress (Sm) – It is the algebraic average of the maximum and minimum stresses in one cycle, i.e., Sm = (Smax + Smin)/2. It is also referred to as steady component of stress.
Mean wall thickness – For a tube this is the sum of four wall thickness measurements, made at 90-degree intervals around the diameter, divided by four.
Measurand – It is a particular quantity subject to measurement. For example, vapour pressure of a given sample of water at 20 deg C. The specification of a measurand can require statements about quantities such as time, temperature, and pressure.
Measured area of the rectified signal envelope (MARSE) – It is sometimes referred to as energy counts. It is the measure of the area under the envelope of the rectified linear voltage time signal from the transducer. This can be thought of as the relative signal amplitude and is useful since the energy of the acoustic emission can be determined. Measured area of the rectified signal envelope is also sensitive to the duration and amplitude of the signal, but does not use counts or user defined thresholds and operating frequencies. It is regularly used in the measurements of acoustic emissions.
Measurement – Measurement is the process by which one can convert physical parameters to meaningful numbers. It is the process of determining the quantity, degree, capacity by comparison (direct or indirect) with the accepted standards of the system units being used. It is a process of comparing an unknown quantity with an accepted standard quantity. The measuring process is one in which the property of an object or system under consideration is compared to an accepted standard unit, a standard defined for that particular property. A measuring instrument can determine the magnitude or value of the quantity to be measured. The measuring quantity can be voltage, current, power, and energy etc. Measurement can be done by direct method of measurement or indirect method of measurement. Measurement of process parameters is an important aspect for the control of a process. Examples of the process parameters which are to be measured for control are pressure, temperature, flow, mass, length, and level etc.
Measurement pillar – Measurement is the third pillar of the quality advantage. An axiom of quality is, ‘one cannot improve what one does not measure’. In every organization, measurements are being done. But in the quality organization, the measurements are needed to track its progress for the right things. The right things for measurements are decided based on the requirements of both the internal and external customers. When people learn to measure quality, they know where and when to take action. They are also being able to document the achievements which result from the quality improvement process. The organization can meet its quality goals if it establishes baselines and charts progress against them. Decisions what to measure and who to measure, are to be heavily influenced by the requirements of the customers. Normally measurement is to be done by those persons who are closest to the work. Also in a quality conscious organization, people make decisions using facts and data then relying on intuition.
Measure of central tendency – It is a central or typical value for a probability distribution. It is frequently called averages. The most common measures of central tendency are the arithmetic mean, the median, and the mode. A middle tendency can be calculated for either a finite set of values or for a theoretical distribution, such as the normal distribution. Occasionally people use it to denote the tendency of quantitative data to cluster around some central value.
Measured Mineral resource – A ‘Measured Mineral resource’ is that part of a Mineral resource for which quantity, grade (or quality), densities, shape, and physical characteristics are estimated with confidence sufficient to allow the application of Modifying factors to support detailed mining planning and final evaluation of the economic viability of the deposit. Geological evidence is derived from detailed and reliable exploration, sampling, and testing gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes, and is sufficient to confirm geological and grade (or quality) continuity between points of observation where data and samples are gathered. A Measured Mineral resource has a higher level of confidence than that applying to either an Indicated Mineral resource or an Inferred Mineral resource. It can be converted to a Proved Ore reserve or under certain circumstances to a Probable Ore reserve.
Measuring equipment – It consists of all of the measuring instruments, measurement standards, reference materials, auxiliary apparatus and instructions which are necessary to carry out a measurement. The term includes measuring instruments used in the course of inspection and testing, as well as those used in calibration.
Measuring instrument – It is a device or mechanism for determining values or magnitude of a quantity or variable. It is used to determine the present value of a quantity under observation. It is the device which is used for comparing the unknown quantity with the unit of measurement or standard quantity. It can be defined as a machine or system which is designed to maintain functional relationship between prescribed properties of physical variables and can include means of communication to human observer. It not to influence the quantity which is to be measured. Measuring instruments are the technical objects which are specially developed for the purpose of measuring specific quantities. A general property of measuring instruments is that their accuracy is known. Measuring instruments are divided into material measures, measuring transducers, indicating instruments, recording instruments, and measuring systems. Measuring instruments can be either (i) analog instrument, or (ii) digital instrument. In the analog instrument, the measured parameter value is displayed by the moveable pointer. The pointer keeps moving continuously with the variable parameter / analog signal which is measured. The reading is inaccurate because of parallax error (parallel) during the reading. In the digital instrument, the measured parameter value is displayed in decimal (digital) form and the reading can be read through in numbers form. Hence, the parallax error is not existed and terminated. The concept used for digital signal in a digital instrument is logic binary ‘0’ and ‘1’.
Mechanical abrasion – It is the process of scuffing, scratching, wearing down, marring, or rubbing away. It can be intentionally imposed in a controlled process using an abrasive. Mechanical abrasion can be an undesirable effect of exposure to normal use or exposure to the elements.
Mechanical activation – It is the acceleration or initiation of a chemical reaction by mechanical exposure of a nascent solid surface. Metal cutting (machining) is an effective method of exposing large areas of fresh surface.
Mechanical adhesion – It is the adhesion between surfaces in which the adhesive holds the parts together by interlocking action.
Mechanical advantage – It is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to get a desired amplification in the output force. The model for this is the law of the lever. Machine components designed to manage forces and movement in this way are called mechanisms. An ideal mechanism transmits power without adding to or subtracting from it. This means the ideal machine does not include a power source, is frictionless, and is constructed from rigid bodies that do not deflect or wear. The performance of a real system relative to this ideal is expressed in terms of efficiency factors which take into account departures from the ideal.
Mechanical alignment – It is a method of aligning the geometrical axis of the electron microscope by relative physical movement of the components, normally as a step preceding magnetic or voltage alignment.
Mechanical alloying (MA) – It is an alternate cold welding and shearing of particles of two or more species of highly differing hardness. The operation is carried out in high-intensity ball mills, such as attritors, and is the preferred method of producing oxide-dispersion-strengthened (ODS) materials.
Mechanical atomizing oil burner – It is a burner which uses the pressure of the oil for atomization.
Mechanical biological treatment (MBT) system – It is a type of waste processing facility which combines a sorting facility with a form of biological treatment such as composting or anaerobic digestion. Mechanical biological treatment plants are designed to process mixed household waste as well as commercial and industrial wastes.
Mechanical blasting process – The process most frequently employs the use of cabinet type equipment. It is available in either batch, semi-automatic or automatic versions. Typically, the cabinet houses one or more blast wheels which direct the abrasive at the steel surface by centrifugal force. The wheel is positioned to ensure maximum coverage and high efficiency of the blast pattern on the steel surface. Clean abrasive, generally air washed and graded, is stored in a hopper. The abrasives flow from the hopper by gravity to a feed funnel and dipper valve which meters the abrasive flow to the impeller. The impeller imparts centrifugal velocity to the abrasive which is then directed through a control cage. The control cage determines the direction and shape of the delivery of the blast pattern on the steel surface. The wheel generally is enclosed in a protective housing to prevent discharge of stray abrasives.
Mechanical bond – It is the adherence of a thermal sprayed deposit to a roughened surface by the mechanism of particle interlocking.
Mechanical cleaning – It is the removing of residues or impurities from steel using mechanical force such as grinding or sand blasting.
Mechanical cleaning systems – These systems are available for the majority of the industrial production applications to remove contaminants and prepare the work surface for subsequent finishing or coating operations. Typical uses include (i) removing rust, scale, dry solids, mold sand, ceramic shell coatings, or dried paint, (ii) roughening surfaces in preparation for bonding, painting, enameling, or other coating substances, (iii) removing large burrs or weld spatter, (iv) developing a uniform surface finish, even when slightly dissimilar surfaces are present, (v) removing flash from rubber or plastic moulding operations, and (vi) carving or decorative etching of glass, porcelain, wood, or natural stone such as granite or marble. Mechanical cleaning systems use different types of abrasive materials which are energized or propelled against the work surface of the part through one of three principal methods namely (i) airless centrifugal blast blade-type or vane-type wheels, (ii) compressed air, direct-pressure dry blast nozzle systems, or (iii) compressed-air, indirect-suction (induction) wet or dry blast nozzle systems.
Mechanical (cold) crack – It is a crack or fracture in a casting resulting from rough handling or from thermal shock, such as which can occur at shake-out or during heat treatment.
Mechanical damage, rolls – Rolls can have mechanical damage. Mechanical damage in rolls can take place because of local mechanical overload. It is quite common to find some intrusions, bruises, impressions on the rolls. These happen when any foreign material enters the rolls along with the material being rolled. The damage to roll take place when the hardness of the foreign material is high or its size is big enough to cause a deep impression on the rolls. In case of deep roll impression, it becomes necessary to machine the rolls.
Mechanical damage, wire rod – Striations, abrasion, and gouging of the rod surface and bruising of the cross section are classed as mechanical damage. Also, due to the mechanical damage, sections of entire coils are kinked or distorted. The defect can be recognized with the naked eye. After leaving the finished stand, the wire rod comes into contact with several mechanical auxiliary and conveying installations such as driving mechanisms, reels push-off gear, suspension chains, conveyer belts, hook conveyers, transfers, and collecting gear. During all these operations, the wire rod is in danger of being getting damaged.
Mechanical descaling processes – These processes are normally used for the removal of scale from the steel rods in the steel rod drawing industry. These processes carry out descaling of steel by (i) reverse bending deformation, (ii) shot-blasting, and (iii) combination of reverse bending and shot blasting.
Mechanical disintegration – it is the process of reducing metal powder particle sizes by mechanical means.
Mechanical draft – It is the negative pressure created by mechanical means.
Mechanical efficiency – It is a dimensionless ratio which measures the efficiency of a mechanism or machine in transforming the power input to the device to power output. A machine is a mechanical linkage in which force is applied at one point, and the force does work moving a load at another point. At any instant the power input to a machine is equal to the input force multiplied by the velocity of the input point, similarly the power output is equal to the force exerted on the load multiplied by the velocity of the load. The mechanical efficiency of a machine (frequently represented by the Greek letter etaη) is a dimensionless number between 0 and 1, i.e., the ratio between the power output of the machine and the power input.
Mechanical engineering – It is engineering discipline which deals with the physical machines which involves force and movement. It is an engineering branch which combines engineering physics and mathematics principles with materials science, to design, analyze, manufacture, and maintain mechanical systems. Mechanical engineering needs an understanding of core areas including mechanics including mechanics, dynamics, thermodynamics, materials science, design, structural analysis, and electricity. In addition to these core principles, mechanical engineers use tools such as computer-aided design (CAD), computer-aided manufacturing (CAM), computer-aided engineering (CAE), and product lifecycle management to design and analyze manufacturing plants, industrial equipment and machinery, heating and cooling systems, transport systems.
Mechanical equilibrium – It is a state of an object in which the net force on the object is zero. By extension, a physical system made up of several parts is in mechanical equilibrium if the net force on each of its individual parts is zero. In addition to defining mechanical equilibrium in terms of force, there are several alternative definitions for mechanical equilibrium. In terms of momentum, a system is in equilibrium if the momentum of its parts is all constant. In terms of velocity, the system is in equilibrium if velocity is constant. In a rotational mechanical equilibrium the angular momentum of the object is conserved and the net torque is zero.
Mechanical filter– It is a signal processing filter normally used in place of an electronic filter at radio frequencies. Its purpose is the same as that of a normal electronic filter, i.e., to pass a range of signal frequencies, but to block others. The filter acts on mechanical vibrations which are the analogue of the electrical signal. At the input and output of the filter, transducers convert the electrical signal into, and then back from, these mechanical vibrations.
Mechanical hysteresis – It is the energy absorbed in a complete cycle of loading and unloading within the elastic limit and represented by the closed loop of the stress-strain curves for loading and unloading. It is sometimes referred to as elastic hysteresis.
Mechanical instruments – The instruments which came into existence in early days were of mechanical nature. The principles on which these instruments worked are even in use today. The earliest scientific instruments used the same three essential elements as the modern instruments use. These elements are (i) detector, (ii) intermediate transfer device, and (iii) indicator, recorder or a storage device. These instruments are very reliable for static and stable conditions. There are a large number of possibilities for mechanical instruments. For example, the instruments can be calipers, micrometers, scales, measuring tapes, and lasers, etc. for measuring distances, pressure gauge for measuring pressure, strain gauges for measuring how much a part is stretched or compressed when a load is applied, tachometer for measuring the rotational speed, multi-meter for measuring electrical voltages and currents, and many others. The disadvantage associated with the mechanical instruments is that they are unable to respond quickly to measurements of dynamic and transient nature. These instruments have several moving parts which are rigid, heavy and bulky and thus they have a large mass. The mass presents inertia problems and hence these instruments cannot follow the rapid changes which are involved in dynamic measurements. Another disadvantage of mechanical instruments is that most of them are a potential source of noise and cause sound pollution. Mechanical instruments are simple in design and application. They are normally durable and relatively cheaper. No external power source is needed for their operation. They are normally quite reliable and accurate for measurements under stable conditions.
Mechanical lifters – They are composed of two or more rigid parts which move in tandem when manually actuated to secure the load.
Mechanical load capacity – In many applications the pressure measuring instruments are sometimes exposed to significant shock and vibration loadings. Vibration loads are oscillating mechanical loads of longer duration. In contrast, shock is considered as an impulse wave which decreases quickly compared to vibration. Strong vibrations have an effect when using pressure measuring instruments. Shocks occur, for example, during its application in machines with high accelerations during operation, such as solid forming presses or drop forges. For the pressure measuring instrument to be used safely in applications with strong vibrations and / or shocks, it is to withstand these loads. The vibration resistance of industrial pressure transmitters is usually in the range of 10 to 20 times the acceleration due to gravity (10 g to 20 g). Nowadays, the shock resistance of industrial pressure transmitters is at several hundred ‘g’.
Mechanically assisted degradation – It is defined as any type of degradation which involves both a corrosion mechanism and a wear or fatigue mechanism. There are five major such forms of degradation which are erosion, fretting, fretting fatigue, cavitation and water drop impingement, and corrosion fatigue.
Mechanically flexible couplings – In general, these couplings obtain their flexibility from loose-fitting parts and / or rolling or sliding of mating parts. Therefore, they usually require lubrication unless one moving part is made of a material that supplies its own lubrication needs (e.g., a nylon gear coupling). Also included in this category are couplings that use a combination of loose-fitting parts and / or rolling or sliding, with some flexure of material.
Mechanical metallurgy – It is the science and technology dealing with the behaviour of metals when subjected to applied forces. It is frequently considered to be restricted to plastic working or shaping of metals.
Mechanical plating – It is the plating wherein fine metal powders are peened onto the work by tumbling or other means. It is a method for coating ferrous metals, copper alloys, lead, stainless steel, and certain types of castings. The process applies a malleable, metallic, corrosion-resistant coating of zinc, cadmium, tin, copper, or aluminum. Combinations of metals can be applied as co-deposits or as ‘sandwich’ layered deposits. Mechanical plating is referred to by a variety of names, including peen plating, impact plating, and mechanical galvanizing. Mechanical plating frequently can solve engineering, economic, and pollution-related plating problems. It offers a straight-forward alternative method for achieving desired mechanical and galvanic properties with an extremely low risk of hydrogen embrittlement. In some situations, it offers a potential cost advantage over electro-plating. Mechanical plating is accomplished at room temperature, without the electrical charge passing through the plating medium which is necessary with electro-plating or electro-coating. The metallic coating is produced by tumbling the parts in a mixture of glass beads, metallic dust or powder, ‘promoter’ or ‘accelerator’ chemicals, and water. The glass beads provide impacting and hammering energy, which serves to pound the metallic particles against the surfaces of the parts. The result is a tight, adherent metallic coating produced by ‘cold welding, fine, powdered metallic particles to the surfaces of parts.
Mechanical polishing – It is a process which yields a specularly reflecting surface entirely by the action of machining tools, which are normally the points of abrasive particles suspended in a liquid among the fibres of a polishing cloth.
Mechanical press – Mechanical press belongs to a class of machine tools which encompass a wide range of different machine types. Primarily, the mechanical press transforms the rotational force of a motor into a translational force vector that performs the pressing action. Hence, the energy in a mechanical press comes from the motor. These types of presses are normally generally faster than hydraulic or screw presses, (actually the screw press can also be classified as a mechanical press). Unlike some presses, in a mechanical press, the application of force varies in both speed and magnitude throughout the distance of the stroke. When performing a manufacturing operation using a mechanical press, the correct range of the stroke is essential. In mechanical presses, a crank, knuckle joint, scotch yoke, or moving-wedge mechanism is used to apply a vertical squeezing motion between the upper moving die and a lower fixed die.
Mechanical press brake – It is a press brake using a mechanical drive consisting of a motor, flywheel, crankshaft, clutch, and eccentric to generate vertical motion.
Mechanical pressure gauges – In mechanical gauges, the motion generated by the pressure sensing device is converted by mechanical linkage into dial or pointer movement. The better gauges provide adjustments for zero, span, linearity, and sometimes temperature compensation for mechanical calibration. High-accuracy mechanical gauges take advantage of special materials, balanced movements, compensation techniques, mirror scales, knife-edge pointers, and expanded scales to improve the precision and accuracy of readings. The most accurate mechanical gauges, test gauges, are used as transfer standards for pressure calibration, but for applications requiring remote sensing, monitoring, or recording they are impractical. Their mechanical linkages also limit their frequency response for dynamic pressure measurements.
Mechanical properties – These are the properties of a material which reveal its elastic and inelastic (plastic) behaviour when force is applied, thereby indicating its suitability for mechanical (load-bearing) applications. Examples are elongation, fatigue limit, hardness, fracture toughness, tensile strength, and yield strength. Some definitions exclude elastic constants (including the modulus of elasticity) from a list of mechanical properties since the value of these constants is controlled by interatomic bonding forces and is therefore a physical property. Others include the elastic constants and use a definition of mechanical properties which include the requirement of the imposition of a force or a deformation to the material. In any event, most mechanical properties are highly (micro) structure sensitive, except for the elastic constants, which in macroscale polycrystalline materials usually do not vary significantly with micro-structure.
Mechanical rectifier – It is an electro-mechanical device for converting alternating current to direct current by using sets of contacts which operate in synchronism with the alternating current.
Mechanical schematic diagrams – A mechanical schematic diagram symbolically depicts elements of the unit, assembly, or system involved and displays the relation of each element by interconnecting lines. The elements are normally arranged functionally or they are actually arranged as in their assembly or installed position. The mechanical schematic diagram depicts mechanical and other functional operation, structural loading, fluid circuitry, or other functions using appropriate standard symbols and connecting lines. It is a design information drawing. It is made when operating principles cannot be readily determined from a study of the assembly drawing. It illustrates design information for (i) hydraulic or pneumatic systems, (ii) complex mechanical systems (complex arrangement of gears, clutches, linkages, and cams, etc.), (iii) rigging instructions, and (iv) critical structural items to display loading or lifting data.
Mechanical seal – It is a device which prevents the leakage of fluids along rotating shafts. Sealing is accomplished by a stationary primary-seal ring bearing against the face of a mating ring mounted on a shaft. Axial pressure maintains the contact between seal ring and mating ring.
Mechanical spalling – In refractory brick it is caused by the stresses resulting from impact or pressure.
Mechanical stability of a grease – It consists of grease shear stability tested in a standard rolling tester. Mechanical stage – It is a device which is provided for adjusting the position of a sample, normally by translation in two directions at right angles to each other.
Mechanical steam traps – These traps are operated by changes in fluid density. This range of steam traps operates by sensing the difference in density between steam and condensate. These steam traps include ‘ball float traps’ and ‘inverted bucket traps’. In the ‘ball float trap’, the ball rises in the presence of condensate, opening a valve which passes the denser condensate. With the ‘inverted bucket trap’, the inverted bucket floats when steam reaches the trap and rises to shut the valve. Both are essentially ‘mechanical’ in their method of operation.
Mechanical stresses – Properties related to mechanical stresses are having importance since they determine the strength of the refractories under different service conditions. The important refractory properties for the mechanical stresses are cold modulus of rupture and deformation modulus, crushing strength, abrasion resistance, porosity, and density.
Mechanical testing – It is the methods by which the mechanical properties of a metal are determined.
Mechanical thermal expression process – This process is the combination of mechanical expression and thermal dewatering process. It is a method which uses mild heat and mechanical compression. For getting substantial benefit from mechanical thermal expression process, it is necessary to heat the lignite coal above the normal boiling temperature of water. However, the processing temperature is to be low enough to prevent significant release of organics into the product water. Around 10 % to 60 % of the initial water is removed during the stage of mechanical compression. The compressive pressure is the major factor influencing the quantity of water removed. Mechanical dewatering process is held in back-pressure to prevent evaporation, ensuring that the water is removed only by mechanical forces. Further moisture reduction is achieved by flash evaporation in the processed lignite coal by exposing it to atmospheric conditions. The mechanical thermal expression process results into the removal of water which is around 75 % maximum of the original moisture content. The mechanical thermal expression process has certain drawbacks such as (i) the need for prior grinding of coal, (ii) the need for clean water produced, (iii) time consuming, and (iv) high investment and operating costs.
Mechanical tubular product – It includes welded and seamless tubes used for a wide variety of mechanical purposes. It is normally produced to meet specific end-use requirements and hence is produced in several shapes, to a variety of chemical compositions and mechanical properties, and with hot rolled or cold finished surfaces. Majority of the mechanical tubes are available as per specifications of different standards. Mechanical tube is not produced to specified standard sizes, but it is produced to specified dimensions, which can be anything which the customer needs within the limits of production equipment or processes. Controlling tolerances are placed on the outside diameter (OD) and wall thickness for hot finished tube and on outside diameter, inside diameter, and wall thickness for cold finished tube. Size is generally expressed in mm. Specifications for size includes any two of the controlling dimensions namely outside diameter, inside diameter, and wall thickness, but never all three. The chemical compositions normally available in mechanical tubes cover a wide variety of standard grades. In addition to the standard grades, several high strength low alloy (HSLA) grades and unique chemistries are produced to customer specifications. When the steel used, either carbon or alloy steel, needs normalizing or annealing after welding, such operations become a part of the specification. For example, a type of welded structural tubing made from carbon steel with nominal carbon content of 0.50 % is normally normalized.
Mechanical twin – It is a twin formed in a crystal by simple shear under external heating.
Mechanical upsetter – It is a three-element forging press, with two gripper dies and a forming tool, for flanging or forming relatively deep recesses.
Mechanical valves – These valves use mechanical energy in the process of opening and closing the actual valve. Larger valves can be opened and closed using mechanical processes such as levers and pulleys, whereas smaller mechanical valves can be opened or closed via a turning wheel or pulling a level by hand.
Mechanical vibrating feeders – The function of these feeders is like the function of electromagnetic vibrating feeders. However, vibrations are created by unbalanced rotating mass, hence tray size, power, force options, and ranges are very large. The tray can be made much stronger and robust, and so they can be used for comparatively difficult bulk materials and also for larger capacities. One can come across mechanical vibrating feeder for capacity up to 1,100 tons per hour of coal or 3,000 tons per hour for iron ore. The material flows in a loose (fluidic) condition and so lumps jamming and forceful abrasion on tray is absent. This is also due to reason that the equipment is not capable in dealing with full extraction of material like apron feeder or belt feeder. The hopper outlet length along tray is of specific (small) dimension, not like long opening in case of belt feeders / apron feeders.
Mechanical wear – It is the removal of material because of the mechanical processes under conditions of sliding, rolling, or repeated impact. The term mechanical wear includes adhesive wear, abrasive wear, and fatigue wear.
Mechanical work – It is the energy transferred to or from an object through the application of force along a displacement. In its simplest form, for a constant force aligned with the direction of motion, the work equals the product of the force strength and the distance traveled. A force is said to do positive work if it has a component in the direction of the displacement of the point of application. A force does negative work if it has a component opposite to the direction of the displacement at the point of application of the force.
Mechanical working – It means the subjecting of metals to pressure exerted by rolls, hammers, or presses in order to change the shape or physical properties of the metal.
Mechanics – It concerns with the relationships between force, matter, and motion among physical objects. Forces applied to objects can result in displacements, which are changes of an object’s position relative to its environment.
Mechanism – It is a device which transforms input forces and movement into a desired set of output forces and movement. Mechanisms normally consist of moving components which can include gears and gear trains, belts and chain drives, cams and followers, linkages, friction devices such as brakes or clutches, structural components such as a frame, fasteners, bearings, springs, or lubricants, and different machine elements such as splines, pins, or keys. In statistical analysis, mechanism is a characteristic which transmits the effect of one variable on another. It is also called an intervening variable or a mediating variable.
Mechanism dynamics – It is the procedure for determining the detailed motions, velocities, and accelerations of the parts in a complex mechanical system. Computer-aided methods, based on the engineering sciences of dynamics and kinematics, are used.
Mechatronics – It consists of combinations of mechanical systems with electronics for sensing and control.
Median – The median is the middle most number in an ordered series of numbers. It is a measure of central tendency, and is frequently a more robust measure of central tendency, that is, the median is less sensitive to outliers than is the sample mean. If the list has an odd number of entries, the median is the middle entry after sorting the list into increasing order. If the list has an even number of entries, the median is halfway between the two middle numbers after sorting.
Median crack – It is the damage produced in glass by the static or translational contact of a hard, sharp object on the glass surface. The crack propagates into the glass perpendicular to the original surface.
Median fatigue life – It is the middle value when all of the observed fatigue life values of the individual sample in a group tested under identical conditions are arranged in order of magnitude. When an even number of samples are tested, the average of the two middlemost values is used. Use of the sample median rather than the arithmetic mean (that is, the average) is normally preferred.
Median fatigue strength at ‘N’ cycles – It is an estimate of the stress level at which 50 % of the population survives ‘N’ cycles. The estimate is derived from a particular point of the fatigue life distribution, since there is no test procedure by which a frequency distribution of fatigue strengths at ‘N’ cycles can be directly observed. It is also known as fatigue strength at ‘N’ cycles.
Median of a variable – It is the value of the variable such that half of the cases are lower in value and half are higher in value.
Medium and high carbon spring steels – These spring steels are the most commonly used materials since they are less expensive. These materials can be easily worked and are readily available. These steels are not suitable for springs operating at high or low temperatures or for shock or impact loading.
Medium carbon steels – These steels are similar to low carbon steels except that the carbon content in these steels is higher and normally in the range of 0.31% to 0.60 % with the manganese content ranging from 0.60 % to 1.65 %. Because of the increased carbon content, the medium carbon steels can be used in the quenched and tempered condition.
Medium cement castable (MCC) – It is characterized by a calcium oxide content higher than 2.5 %.
Mega Pascals – It is the SI (International System of Units) unit for measuring the strength of a material and is abbreviated to MPa. Numerically it is exactly equivalent to Newtons/square millimeter.
Megawatt – It is equal to one million watts. The productive capacity of electrical generators operated by a power plant is frequently measured in megawatts.
Methyl ethyl ketone (MEK) – It is also known as butanone. It is an organic compound with the formula CH3C(O)CH2CH3. This colourless liquid ketone has a sharp, sweet odour reminiscent of acetone. It is produced industrially on a large scale, but occurs in nature only in trace quantities. It is partially soluble in water, and is normally used as an industrial solvent. It is an isomer of another solvent, tetrahydrofuran.
MEK test – For this test, cotton wool is soaked in MEK solution. 1 kilogram load is applied on the sample and the sample is rubbed by cotton wool up by thumb for 100 times. Cotton wool is re-soaked in the MEK solution after every 25 rubs. The sample is observed for colour coating getting peel off.
Melilite – It refers to a mineral of the melilite group. Minerals of the group are solid solutions of several end-members, the most important of which are gehlenite and akermanite. A generalized formula for common melilite is (Ca,Na)2(Al,Mg,Fe2+)[(Al,Si)SiO7]. It has a yellowish, greenish-brown colour. The name refers to a group of minerals (melilite group) with chemically similar composition, nearly always minerals in akermanite-gehlenite series.
Melt – It is a charge of molten metal or plastic.
Melting behaviour – The melting behaviour of a mould powder strongly influences both the liquid pool depth and the sensitivity towards rim / bear formation. The melting behaviour can be described by the melting trajectory and the melting speed. In both cases, additions of free carbon are considered to be a principal factor. The other main parameter is the flow condition in the mould i.e. the meniscus stability during casting. The liquid pool depth results from the balanced values of the feeding and the infiltration of the mould powder.
Melt index – It is the quantity, in grams, of a thermoplastic resin which can be forced through a 2.0955 millimeters orifice when subjected to 20.7 Newton (2,160 gram-force) in 10 minutes at 190 deg C.
Melting furnaces – These furnaces are used to heat solid materials until they liquefy by generating temperatures above the material’s melting point.
Melting point – It is the temperature at which a pure metal, compound, or eutectic changes from solid to liquid. It is the temperature at which the liquid and the solid are at equilibrium.
Melting pressure – At a stated temperature, it is the pressure at which the solid phases of an element or congruently melting compound can coexist at equilibrium with liquid of the same composition.
Melting range – It is the range of temperatures over which an alloy other than a compound or eutectic changes from solid to liquid. It is the range of temperatures from solidus to liquidus at any given composition on a phase diagram.
Melting speed – The melting speed of mould powders is determined using the so-called softening method. With this method, the displacement of a pre-pressed cylinder of mould powder is measured as a function of time at a fixed temperature (1,400 deg C). The method yields qualitative results which can be related to the mould powder composition i.e. the free carbon content of a mould powder.
Melting temperature – It is the temperature at which a pure metal, compound, or eutectic changes from solid to liquid. It is the temperature at which the liquid and the solid are at equilibrium.
Melting tower – It is a part of the continuous tinning line. In this melting tower the process of tin reflow takes place while the electrolytic coated tinplate passes through the tower. In the melting tower section, the temperature of the strip is raised by resistance or induction heating to just above the melting point of tin (231.9 deg C) and then the strip is immediately quenched with cold water. The tin begins to melt and reflows uniformly across the strip. The product now takes on the more typical bright or shiny surface appearance. In case a matte (unmelted) tin finish is needed then the melting tower is turned off. When differentially coated tinplate is being produced then an identifying mark is normally placed on either side of the strip just prior to melting.
Melting trajectory – The melting trajectory of the mould powder is determined using a hot stage microscope. Results are normally given as values for the softening, the melting and the flow temperatures.
Melt lubrication – It is the lubrication which is provided by steady melting of a lubricating species. It is also known as phase-change lubrication.
Melt-quenching – It is the traditional technique of glass making and includes mixing of ingredients, heating up to a temperature normally higher than 1,300 deg C and quenching of the glass melt to get a glass frit.
Melt-through – It means complete joint penetration for a joint welded from one side. Iy is the visible root reinforcement produced in a joint welded from one side.
Melt viscosity – It is the bulk property of a fluid or semi-fluid (melted) polymer which causes it to resist flow. It is given by the shear stress acting on the fluid divided by the rate of shear. Melt viscosity in polymers is normally measured by the melt index.
Membrane – It is a selective barrier. It allows some things to pass through but stops others. Such things can be molecules, ions, or other small particles. Membranes can be normally classified into synthetic membranes and biological membranes. Biological membranes include (i) cell membranes (outer coverings of cells or organelles which allow passage of certain constituents), (ii) nuclear membranes, which cover a cell nucleus and (iii) tissue membranes, such as mucosae and serosae. Synthetic membranes are made by humans for use in laboratories and industry (such as chemical plants).
Membrane-based gas separation – Advanced membrane-based gas separation systems are currently being developed to combine the gas shift reaction and hydrogen separation in one step. The membrane-based systems employ a water gas shift hydrogen separation membrane reactor (HSMR) to shift the syngas and extract the hydrogen. The maximum temperature of around 475 deg C ensures fast chemical kinetics and good water gas shift equilibrium performance is obtained by continuous removal of the hydrogen product. There are three major classes of inorganic H2 permeable membranes namely (i) ceramic molecular sieving, (ii) dense ceramic ion transport, and (iii) dense metal.
Membrane bioreactors (MBR) – These are combinations of membrane processes like micro-filtration or ultra-filtration with a biological wastewater treatment process, the activated sludge process. These technologies are now widely used for industrial wastewater treatment. There are two types of membrane bioreactor configurations namely immersed and side-stream. Immersed systems are more common in large industrial units, whereas side-stream is limited to smaller units. There are also differences in the membrane employed from hollow fibre, flat plate, and tubular. Immersed membrane bioreactors use hollow fibre or flat plate whereas tubular membranes are used in side-stream membrane bioreactors. Membrane bioreactor produces an equivalent treatment level to an activated sludge process followed by micro-filtration or ultra-filtration. Despite the advantages of membrane bioreactors, there are still challenges in using membrane bioreactors in industrial applications. The advantages of membrane bioreactor are (i) 25 % lower footprint, (ii) replaces the clarifier and gravity filter of conventional systems, (iii) ideal for land constrained sites and lower hydraulic retention time of 4 hours to 8 hours. Membrane bioreactor provides impermeable barrier for solids producing highest quality effluent with biological oxygen demand (BOD) less than 5 milligrams per litre and turbidity of less than 0.1 NTU (Nephelometric turbidity unit). Membrane fouling is one of the major challenges which results in reduced performance and frequent cleaning or membrane replacement leading to increased maintenance and operating costs. All membrane bioreactor need a minimum of fine screens of 3 millimeters. Sludge produced can be difficult to dewater. Sludge retention time is independent of hydraulic retention time. High sludge age of 15 days to 140 days can be obtained. It has modular expandability, less odour, and flexible operation with less susceptible to upsets. The process can be automated.
Membrane distillation – Alternative new technologies such as membranes are easing even further the removal of ammonia from flushing liquors. Membrane distillation is being investigated worldwide as a highly efficient and affordable technology. Hydrophobic membranes (flat-sheet, hollow fibre, and spiral wound) are preferred for ammonia extraction due to their hydrophobic characteristics, excellent organic resistance, and chemical stability with acidic and alkaline solutions. The strong hydrophobicity of the membrane prevents liquid transportation through it, hence facilitating the separation of species with different vapour pressures. The partial pressure gradients across the membrane results in the transfer of the volatiles from the liquid phase to the vapour phase. As the temperature gradient is maintained across the membrane, the transport of water vapour occurs continuously. Meanwhile, other species remain on the other side of the membrane, hence separating water from the mixture. Conventional flat-sheet porous have been applied for membrane distillation with efficiencies varying between 70 % to 90 %.
Membrane technology – Membranes are a popular choice for water reuse applications. Costs of membrane systems have reduced dramatically and, coupled with technological advances in membrane design, membrane options and operating limits, the range of applications in water and wastewater treatment is increasing rapidly. In pressure driven membrane filtration, membranes separate the components of a fluid under pressure. The membrane pores, being extremely small, allow the selective passage of solutes. The popularity of membrane processes arises from the fact that they are effective in the removal of both dissolved and suspended solids. A wide range of materials like cellulose acetate, polyamides, poly- sulfones, poly-propylene, nylon, poly-acrylonitrile, poly-carbonate, polyvinyl alcohol, poly-tetra-fluoro-ethylene, ceramic, and metal composites are basically used to produce the membranes. The membrane pore size is the parameter for the degree of selectivity of a membrane. On the basis of the pore size, there are four types of pressure driven membranes. Micro-filtration and ultra-filtration are low pressure applications given their larger pore size. Nano-filtration needs medium pressure, and ‘reverse osmosis, given the smaller pore size, needs significant pressure to push the solute through the membrane.
Menstruum method – It is a method of producing multi-carbide powder, such as tungsten carbide + titanium carbide solid solutions, by introducing the individual elements into a molten bath of a non-carbide forming metal such as aluminum or nickel. The multi-carbide which is formed above 2,100 deg C, is slowly cooled in the dispersed condition in the menstruum to room temperature, and finally won by chemical separation.
Mer– It is the repeating structural unit of a polymer.
Mercaptans – These are chemicals containing carbon, hydrogen, and sulphur. They are detectable at concentrations as low as 10 parts per billion. In some cases, mercaptans are used as an additive to odourless gases for detecting the odourless gases. Methyl mercaptan (also known as methanethiol) is a common mercaptan. In addition to carbon, it contains sulphur. Another example of a common mercaptan is ethyl mercaptan which has the formula C2H5SH.
Merchant bar – It is a group of commodity steel shapes which consist of rounds, squares, flats, strips, angles, and channels, which fabricators, steel service centres, and manufacturers cut, bend, and shape into products. Merchant products need more specialized processing than reinforcement bar.
Merchant mill – It is a mill, consisting of a group of stands of three rolls each arranged in a straight line and driven by one power unit. It is used to roll rounds, squares, or flats of smaller dimensions than are to be rolled on a bar mill.
Mercury – It is a chemical element It has symbol Hg and atomic number 80. It is also known as quicksilver. It is the only metallic element that is known to be liquid at standard temperature and pressure. It is a toxic pollutant. It is ubiquitous in the environment and is unique among metals in that it is highly volatile. When materials containing mercury are burned, as in coal combustion or waste incineration, mercury is released to the atmosphere as a gas either in elemental form, Hg (O) or oxidized divalent form Hg2+. The oxidized form is present as water-soluble compounds such as mercury chloride (HgCl2) which are readily deposited in the region of their emission. By contrast, Hg (O) is not water-soluble and is required to be oxidized to Hg2+ in order to be deposited. This oxidation takes place in the atmosphere on a time scale of one year, sufficiently long that mercury can be readily transported around the world by atmospheric circulation. Mercury hence is a global pollution issue.
Mercury-arc rectifier – It is a mercury-arc valve, a vacuum tube device which converts alternating current to direct current by an arc in mercury vapour. It has been displaced by solid-state devices, but formerly much used especially in high-voltage direct current transmission.
Mercury vapour lamp – It is a lamp which generates light from a discharge struck in mercury vapour. It has formerly been widely used in outdoor lighting, now replaced by lamps with better efficacy.
Mergers and acquisitions (M&A) – These are the general terms which are used for the consolidation of organizations or the assets. The terms ‘merger’ and ‘acquisition’ are used as though they are synonymous, but both of these terms mean slightly different things. Mergers and acquisitions are complex and involve many parties. They involve many issues which include (i) corporate governance, (ii) form of payment, (iii) legal issues, (iv) contractual issues, and (v) regulatory approvals. Merger and acquisition also need application of the valuation tools for the evaluation of the mergers and acquisition decision. A merger happens when two organizations, frequently of about the same size, agree to go forward as a single new organization rather than remain separately owned and operated. In case of an acquisition there is a take-over of one organization by another organization in which no new organization is formed. From a legal point of view the organization which has been taken over ceases to exist and the buyer organization swallows the total operations of the taken over organization.
Merwinite – It is a mineral which forms at high temperatures during the thermal metamorphism of carbonate rocks, along with spurrite and larnite, under specific pressure and temperature conditions.
Mesh – It is a measurement of particle size frequently used in determining the particle-size distribution of a granular material. Several standardized mesh series have been established. Several mesh sizes have been historically given in the number of holes per inch; due to the width of the wires in the mesh, mesh numbers did not correspond directly to fractional inch sizes, and several different systems standardized with slightly different mesh sizes for the same mesh numbers. It is also called mesh size. It is also the screen number on the finest screen of a specified standard screen scale through which almost all of the particles of a powder sample are going to pass. Available sieve sizes are normally regulated by standards. Those in common use are ISO 565:1990 and ISO 3310-1:2000 standards.
Mesh analysis – It is a strategy for solution of the voltage distribution in some types of electrical networks.
Mesh-belt conveyor furnace – It is a continuously operating furnace which uses a conveyor belt for the transport of the charge.
Mesh networking – It is a topology where infrastructure nodes connect to other nodes such as to convey information.
Mesh number – It is the number of screen openings per linear inch of the screen. It is also called mash size. Mesh number is also the screen number of the finest screen through which all of the particles of a given powder passes.
Mesh size – It is the width of the aperture in a cloth or wire screen.
Mesophase – It is an intermediate phase in the formation of carbon from a pitch precursor. This is a liquid crystal phase in the form of micro-spheres, which, upon prolonged heating above 400 deg C, coalesce, solidify, and form regions of extended order. Heating to above 2,000 deg C leads to the formation of graphite structure.
Mesoscopic – It is pertaining to the size range between microscopic and macroscopic.
Metadata – It is the descriptive data about the material for which data are reported. Metadata include a complete description of the material (producer, heat number, grade, and temper etc.), a complete description of the test method, and information about the test plan.
Meta-dynamic recrystallization – It is the recrystallization which occurs during the cooling phase of a hot-working process or between successive passes. It occurs at strains higher than critical strain. It is observed to be a strong function of strain rate and a very weak function of temperature and strain.
Metadyne -m It is a direct current electric machine with crossed fields and two sets of brushes, used as an amplifier or rotary direct current transformer.
Metal – It is an opaque lustrous elemental chemical substance which is a good conductor of heat and electricity and, when polished, a good reflector of light. Majority of the elemental metals are malleable and ductile and are, in general, denser than the other elemental substances. As to structure, metals can be distinguished from non-metals by their atomic binding and electron availability. Metallic atoms tend to lose electrons from the outer shells, the positive ions hence formed being held together by the electron gas produced by the separation. The ability of these ‘free electrons’ to carry an electric current, and the fact that this ability decreases as temperature increases, establish the prime distinctions of a metallic solid. From a chemical viewpoint, metal is an elemental substance whose hydroxide is alkaline. It is also an alloy.
Metal alloy – It is a mixture of chemical elements of which in majority of the cases at least one is a metallic element, although it is also sometimes used for mixtures of elements. Majority of the metallic alloys are metallic and show good electrical conductivity, ductility, opacity, and lustre, and can have properties which differ from those of the pure elements such as increased strength or hardness. In some cases, an alloy can reduce the overall cost of the material while preserving important properties. In other cases, the mixture imparts synergistic properties such as corrosion resistance or mechanical strength.
Metal arc cutting – It consists of a group of arc-cutting processes which severs metals by melting them with the heat of an arc between a metal electrode and the base metal.
Metal arc welding – It consists of a group of arc welding processes in which metals are fused together using the heat of an arc between a metal electrode and the work. Use of the specific process name is preferred.
Metal carbide – It is normally described as a compound composed of carbon and a metal.
Metal carbonates – It is the coating for welding electrode which is to adjust the basicity of the slag and to provide a reducing atmosphere.
Metal casting process – It is the simplest and most direct route to a near net shape product and frequently the least expensive process. This process in its fundamental form needs a mould cavity of the desired shape and liquid metal to pour into the mould cavity. Metal castings are being produced most frequently by pouring of liquid metal into moulds made of sand. The basic components of a mould cavity are cope, drag, parting line, riser, sprue (a channel through which the liquid metal is poured into a mould), and pouring basin etc., as well as the liquid metal handling system known as a ladle. The casting process begins with the making of a mould, which is the ‘reverse’ shape of the part which is to be cast. The mould is made from a refractory material, for example, sand. The metal is heated in a furnace until it melts, and then the liquid metal is poured into the mould cavity. The liquid takes the shape of cavity, which is the shape of the part. It is cooled until it solidifies. Finally, the solidified metal part is removed from the mould.
Metal coated steels – These steels are defined as a steel substrates coated with a layer of zinc, zinc / aluminum alloy, zinc / silicon alloy, pure aluminum, lead / tin alloy. tin, or chromium etc. Metal coatings of steels improve the life and the performance of the steels. They provide the most effective and economical way of protecting steels against corrosion. Metal coated steels offer unique combination of properties which include high strength, formability, light weight, corrosion resistance, aesthetics, recyclability and low cost.
Metal cored electrode – It is a composite filler metal welding electrode which is consisting of a metal tube or other hollow configuration containing alloying ingredients. Minor quantities of ingredients facilitate arc stabilization and fluxing of oxides. External shielding gas may or may not be used.
Metal deactivators, metal deactivating agents (MDA) – These are fuel additives and oil additives which are used to stabilize fluids by deactivating (normally by sequestering) metal ions, mostly introduced by the action of naturally occurring acids in the fuel and acids generated in lubricants by oxidative processes with the metallic parts of the systems. Metal deactivators inhibit the catalytic effects of such ions, retarding the formation of gummy residues.
Metal dusting – It consists of accelerated deterioration of metals in carbonaceous gases at high temperatures to form a dust-like corrosion product.
Metal electrode – It is an electrode used in arc welding or cutting which consists of a metal wire or rod that is either bare or covered with a suitable covering or coating.
Metal forging – It is a deformation process where metal is pressed, pounded or squeezed under great pressure into high strength parts known as metal forgings. The forging process is entirely different from the casting (or foundry) process, as metal used to make forged parts is neither melted nor poured as in the casting process.
Metal forming processes – The term metal forming refers to a group of manufacturing processes by which the given material, normally shapeless or of a simple geometry, is transformed into a useful part without change in the mass or composition of the material. This part normally has a complex geometry with well-defined (i) shape, (ii) size, (iii) accuracy and tolerances, (iv) appearance, and (v) properties. Metal forming processes are primary shaping processes in which a mass of metal or alloy is subjected to mechanical forces. Under the action of such forces, the shape and size of metal piece undergo a change. By mechanical working processes, the given shape and size of a machine part can be achieved with high economy in material and time. These processes consist of deformation processes in which a metal work-piece (billet, bloom, or blank) is shaped by tools or dies. The design and control of such processes depend on the characteristics of the material of the work piece, the requirements of the finished product, the conditions at the interface of the tool and the work piece, the mechanics of plastic deformation (metal flow), and the equipment used. These factors influence the selection of geometry and material of the tool as well as processing conditions (examples are temperatures of die and work piece and lubrication). Since several of the metalworking operations are rather complex, models of different types, such as analytical, physical, or numerical models, are frequently used to design these processes.
Metal-induced embrittlement (MIE) – It is the embrittlement caused by diffusion of metal, either solid or liquid, into the base material. Metal induced embrittlement occurs when metals are in contact with low-melting point metals while under tensile stress. The embrittler can be either solid metal-induced embrittlement (SMIE) or liquid metal-induced embrittlement (liquid metal embrittlement). Under sufficient tensile stress, metal-induced embrittlement failure occurs instantaneously at temperatures just above melting point. For temperatures below the melting temperature of the embrittler, solid-state diffusion is the main transport mechanism. This occurs in the several ways such as (i) diffusion through grain boundaries near the crack of matrix, (ii) diffusion of first monolayer heterogeneous surface embrittler atoms, (iii) second monolayer heterogenous surface diffusion of embrittler, and (iv) surface diffusion of the embrittler over a layer of embrittler. The main mechanism of transport for solid metal-induced embrittlement is surface self-diffusion of the embrittler over a layer of embrittler that’s thick enough to be characterized as self-diffusion at the crack tip. In comparison, liquid metal-induced embrittlement dominant mechanism is bulk liquid flow that penetrates at the tips of cracks.
Metal injection moulding (MIM) – It is a metal-working process in which finely-powdered metal is mixed with binder material (40 % polymer) to create a ‘feedstock’ which is then shaped and solidified using injection moulding. The part is removed from the mould, the binder is removed using either solvent extraction or thermal processes, and the part is sintered to decrease porosity. Metal injection moulding combines the most useful characteristics of powder metallurgy and plastic injection moulding to facilitate the production of small, complex-shaped metal components with outstanding mechanical properties. The moulding process allows high volume, complex parts to be shaped in a single step. After moulding, the part undergoes conditioning operations to remove the binder (debinding) and densify the powders. Finished products are small components used in several industries and applications.
Metallic bond – It is the principal bond between metal atoms, which arises from the increased spatial extension of valence-electron wave functions when an aggregate of metal atoms is brought close together. An example is the bond formed between base metals and filler metals in all welding processes.
Metallic bonding – It is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It can be described as the sharing of free electrons among a structure of positively charged ions (cations). Metallic bonding accounts for several physical properties of metals, such as strength, ductility, thermal and electrical resistivity and conductivity, opacity, and lustre.
Metallic fibre – It is manufactured fibre which is composed of metal, plastic-coated metal, metal-coated plastic, or a core completely covered by metal.
Metallic gaskets – These gaskets can be fabricated in a variety of shapes and sizes recommended for use in high pressure / temperature applications. These gaskets need a much higher quality of the sealing surface than non-metallic gaskets. Except for weld ring gaskets, high loads are needed to seat metallic gaskets, since they rely on the deformation or coining of the material into the flange surfaces. Examples are ring type joints, lens rings, weld rings, and solid metal gaskets etc.
Metallic glass – It is a non-crystalline metal or alloy, normally produced by drastic supercooling of a molten alloy, by molecular deposition, which involves growth from the vapour phase (e.g., thermal evaporation and sputtering) or from a liquid phase (e.g., electroless deposition and electro-deposition), or by external action techniques (e.g., ion implantation and ion beam mixing).
Metallic membrane couplings – In general, the flexibility of these couplings is obtained from the flexing of thin metallic disks or diaphragms.
Metallic wear – Typically, it is the wear because of the rubbing or sliding contact between metallic materials which shows the characteristics of severe wear, e.g., considerable plastic deformation, material transfer, and indications that cold welding of asperities possibly has taken place as part of the wear process.
Metallization – It is a measure of the conversion of iron oxides into metallic iron (either free, or in combination with carbon as cementite) by removal of oxygen due to the action of the reductant used. Degree of metallization refers to that portion of the total iron present as metallic iron and is given by the equation ‘Degree of metallization = (weight of metallic iron/weight of total iron) x 100 = (Fe M/Fe T) x 100’.
Metallizing – It is the application of an electrically conductive metallic layer to the surface of another material. It is also the application of metallic coatings by non-electrolytic procedures such as spraying of molten metal and deposition from the vapour phase. Zinc wire or powder is applied to an abrasive blast cleaned steel surface through a gas flame which melts the zinc. Metalizing is forming a metallic coating by atomized spraying with molten zinc or by vacuum deposition. It is also called spray metalizing. Metalizing is used to repair large damaged areas of galvanized coating.
Metallograph – It is an optical instrument designed for visual observation and photo-micrography of prepared surfaces of opaque materials at magnifications of 25x to around 2,000×. The instrument consists of a high-intensity illuminating source, a microscope, and a camera bellows. On some instruments, provisions are made for examination of the sample surfaces using polarized light, phase contrast, oblique illumination, dark-field illumination, and bright-field illumination.
Metallography – It is the study of the structure of metals and alloys by different methods, especially by optical and electron microscopy.
Metalloid – It is a chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and non-metals. There is no standard definition of a metalloid and no complete agreement on which elements are metalloids. The six commonly recognized metalloids are boron, silicon, germanium, arsenic, antimony and tellurium. Five elements are less frequently so classified are carbon, aluminum, selenium, polonium, and astatine.
Metallo-physical reaction – An example of this is the embrittlement caused by hydrogen which diffuses into steel, possibly leading to failure of a component. Embrittlement can be the result of a careless manufacturing process, e.g. when surface coatings such as electrochemical zinc plating are not applied properly on high-strength steel products (primary embrittlement). It can also be initiated by corrosion processes (metal dissolution). In the latter case, reference is made to corrosion-induced hydrogen assisted cracking (secondary embrittlement).
Metallurgical and material engineering – It is the discipline which applies the knowledge of engineering to study, develop, design and operate processes which transforms raw materials into useful engineering product intended to improve technological advancement in different industrial applications such as aerospace, automobile and other sectors of the industry. This branch of engineering is known as the bedrock of engineering discipline. It has close links with other engineering branches.
Metallurgical bond – It is the principal bond which holds metal together and is formed between base metals and filler metals in all welding processes. This is a primary bond arising from the increased spatial extension of the valence electron wave functions when an aggregate of metal atoms is brought close together. It is also referred to as metallic bond. In galvanizing, it is the bonding of iron / zinc inter-metallic layers to the base steel.
Metallurgical burn – It is the modification of the micro-structure near the contact surface because of the frictional temperature rise.
Metallurgical coal – It is the coal which is used for carbonizing in coke oven for the production of metallurgical coke. There are three types of metallurgical coal namely (i) hard coking coal (HCC), (ii) medium coking coal (MCC), and (iii) semi-soft coking coal (SSCC) or weak coking coal. Metallurgical coals are normally classified as high, medium, and low volatile based on their dry, mineral matter free volatile matter (VM). High volatile coals have volatile matter typically between 31 % and 38 %, medium volatile coals have volatile matter between 22% and 31 %, and low volatile coals have volatile matter between 17 % and 22 %. There is normally a strong inverse relation between vitrinite reflectance and dry ash free volatile matter content.
Metallurgical coke – Metallurgical coke is a hard carbon material produced in the process of the ‘destructive distillation’ of different blends of bituminous coal. It is produced by carbonization of coal at high temperatures (1,100 deg C) in an oxygen deficient atmosphere in a coke oven. Coke is essential for the blast furnace iron making process in order to support the burden and provide gas permeability, thus a minimum coke burden limit exists. Coke constitutes a major portion of the production costs of hot metal. Other than economical aspects, coke consumption is also strongly related to the CO2 (carbon di-oxide) emissions and hence to the environmental problems. It is normally low in sulphur, has a very high compressive strength at high temperatures. It is used in metallurgical furnaces not only as fuel, but also to support the weight of the charge.
Metallurgical compatibility – It is a measure of the extent to which materials are mutually soluble in the solid state.
Metallurgical industrial furnaces – These furnaces are used in the metallurgical industry for carrying out different metallurgical processes. Metallurgical furnaces are mostly used for (i) extraction of metals from ores, (ii) calcining and sintering of ores, (iii) melting, refining and alloying of metals, (iv) heating of metals, (v) carbonizing of coals, and (vi) heat treatment of metals etc. Energy sources for metallurgical furnaces are (i) combustion of fossil fuels, such as solid, liquid and gaseous fuels, (ii) electric energy such as resistance heating, induction heating or arc heating, and (iii) chemical energy such as exothermic reactions.
Metallurgically influenced corrosion – It is the corrosion which is caused by the metallurgical factors. These factors include alloy chemistry and heat treatment. The metallurgical influences on corrosion are the relative stability of the components of an alloy, metallic phases, metalloid phases such as carbides, and local variations in composition in a single phase. One example is the ways in which nonmetallic inclusions, such as oxides and sulphides can influence corrosion. Dealloying, selective leaching, and parting are terms used to describe that form of corrosion in which an element is selectively removed from an alloy. Stress corrosion and hydrogen embrittlement are mechanisms which have influence on corrosion. The most common form of metallurgically influenced corrosion is intergranular corrosion. It occurs when corrosion is localized at grain boundaries. Frequently, this localized corrosion leads to the dislodgement of individual grains and a roughening, or sugaring, of the affected surface. It is typified by an apparent increase in the corrosion rate with time.
Metallurgical test – It consists of studies pertaining to the production, purification and properties of metals and their extraction
Metallurgy – It is the science and technology of metals and alloys. Process metallurgy is concerned with the extraction of metals from their ores and with refining of metals. Physical metallurgy deals with the physical and mechanical properties of metals and their alloys affected by composition, processing, and environmental conditions, and mechanical metallurgy is concerned with the response of metals to the applied forces. There are other branches of metallurgy which deals with material testing and analysis, heat treatment, metallography and micro-structures, refractories, composites, energy, nano-metals, metal powders, material characterization, fractures, fractography and failure analysis, tribology, surface engineering, metal joining, and metal forming etc.
Metal-matrix composite – It is a material which consists of a non-metallic reinforcement, such as ceramic fibres or filaments, incorporated into a metallic matrix. Metal-matrix composites are advanced composites which have a non-metallic reinforcement incorporated into a metallic matrix. Reinforcements can constitute from 10 % to 60 % of the composite. Continuous fibre or filament reinforcements include graphite, silicon carbide, boron, alumina, and refractory metals. Matrix materials include aluminum (the most common), titanium, magnesium, copper, and ordered inter-metallic compounds such as nickel-aluminum (NiAl) and titanium aluminum (Ti3Al).
Metal-organic chemical vapour deposition (MOCVD) – It is a controlled synthesis method that involves vapor phase reactions to grow materials with precise control over precursor ratios, growth time, and growth rate, particularly useful for synthesizing wafer-scale uniform transition metal dichalcogenides (TMDs) in the field of chemistry.
Metal-oxide-semiconductor field-effect transistor (MOSFET) – It is a type of field-effect transistor (FET), which is normally fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the quantity of applied voltage can be used for amplifying or switching electronic signals. The main advantage of a MOSFET is that it needs almost no input current to control the load current, when compared to bipolar junction transistors (BJTs).
Metal penetration – It is a surface condition in metal castings in which metal or metal oxides have filled voids between sand grains without displacing them.
Metal pipes and tubes – Metallic pipes are commonly made from iron or steel with the metal chemistry and its finish being peculiar to the use fit and form. Typically, metallic piping can be made of steel or iron, such as unfinished, black (lacquer) steel, carbon steel, stainless steel, or galvanized steel, brass, and ductile iron. Aluminum pipe or tube can be used where iron is incompatible with the service fluid or where weight is a concern. Aluminum is also used for heat transfer tubes such as in refrigerant systems. Copper tube is popular for domestic water (potable) plumbing systems. Copper can also be used where heat transfer is desirable (i.e. radiators or heat exchangers). Inconel, chrome molybdenum, and titanium steel alloys are used for high temperature and pressure piping in process systems where corrosion resistance is important.
Metal powder – Metal powder is a metal that has been broken down into a powder form. Metals that can be found in powder form include aluminium powder, nickel powder, iron powder and many more. There are four different ways metals can be broken down into this powder form namely direct reduction, gas atomization, liquid atomization, and centrifugal atomization. Metal powder is elemental metals or alloy particles, normally in the size range of 0.1 micrometers to 1,000 micrometers.
Metal powder cutting – It is a technique which supplements an oxy-fuel torch with a stream of iron or blended iron-aluminum powder to facilitate flame cutting of difficult-to-cut materials. The powdered material propagates and accelerates the oxidation reaction, as well as the melting and spalling action of the materials to be cut.
Metal rectifier – It is a rectifier made from copper oxide or selenium. It has been formerly widely used before development of silicon rectifiers.
Metal rolling – Metal rolling operations are similar in that the work piece is plastically deformed by compressive forces between two constantly spinning rolls. These forces act to reduce the thickness of the metal and affect its grain structure. The reduction in thickness can be measured by the difference in thickness before and after the reduction, this value is called the draft. In addition to reducing the thickness of the work, the rolls also act to feed the material as they spin in opposite directions to each other. Friction is hence a necessary part of the rolling operation, but too much friction can be detrimental for a variety of reasons. It is essential that in a metal rolling process the level of friction between the rolls and work material is controlled, use of lubricants can help with this. During a metal rolling operation, the geometric shape of the work is changed but its volume remains essentially the same.
Metal shadowing – It is the improvement of contrast in a microscope by vacuum deposition of a dense metal onto the sample at an angle normally not perpendicular to the surface of the sample.
Metal spraying – It consists of coating metal objects by spraying molten metal against their surfaces.
Metal thin-film sensor – The main body and the diaphragm of a metal thin-film sensor are normally made of stainless steel. The sensor can be produced with the required material thickness by machining the diaphragm in automatic precision lathes and then grinding, polishing and lapping it. On the side of the diaphragm not in contact with the medium, insulation layers, strain gauges, compensating resistors and conducting paths are applied using a combination of chemical vapour deposition (CVD) and physical vapour deposition (PVD) processes and are photo-litho-graphically structured using etching. These processes are operated under clean room conditions and in specialized plants, in some parts under vacuum or in an inert atmosphere, in order that structures of high atomic purity can be generated. The resistors and electrical conducting paths produced on the sensor are significantly smaller than a micrometer and are thus known as thin-film resistors. The metal thin-film sensor is very stable because of the materials used. In addition, it is resistant to shock and vibration loading as well as dynamic pressure elements. Since the materials used are weldable, the sensor can be welded to the pressure connection. It can be hermetically sealed without any additional sealing materials. As a result of the ductility of the materials, the sensor has a relatively low overpressure range but a very high burst pressure.
Metal vapour vacuum arc – It provides a means of creating a dense plasma from a conducting solid material, from which a high current ion beam can be extracted.
Metal working – It consists of making a change, with the exception of shearing or blanking, in the shape or contour of a metal part without intentionally altering its thickness. It means the plastic deformation of a billet or a blanked sheet between tools (dies) to get the final configuration. Metal forming processes are typically classified as bulk forming and sheet forming.
Metal working processes -These are the deformation processes in which a metal billet or blank is shaped by tools or dies. In metal working, an initially simple work-piece (e.g., a billet or a blanked sheet) is plastically deformed between tools (or dies) to get the desired final configuration. The design and control of such processes depend on the characteristics of the work-piece material, the conditions at the tool / work-piece interface, the mechanics of plastic deformation (metal flow), the equipment used, and the finished-product requirements. These factors influence the selection of tool geometry and material as well as processing conditions (e.g., work-piece and die temperatures, and lubrication). Because of the complexity of several metal working operations, models of different types, such as analytical, physical, or numerical models are frequently relied upon to design such processes.
Metamorphic rocks – These are the rocks which have undergone a change in texture or composition as the result of heat and / or pressure.
Metamorphism – It is the process by which the form or structure of rocks is changed by heat and pressure.
Metamorphogenic (metamorphosed) deposits – These deposits of iron ore are pre-existing primarily sedimentary deposits which are transformed under conditions of high temperature and pressure. Under such conditions, hydrous ferric oxides and siderite normally become hematite and magnetite. Metamorphic processes are sometimes supplemented by hydro-thermal-metasomatic formation of magnetite ores.
Metamorphosed iron formations – These include the metamorphosed bedded ferruginous rocks composed usually of alternating thin layers of fine-grained quartz and ferric oxides. The iron is normally present in the mineral form of magnetite or hematite, along with lesser amounts of iron silicates and iron carbonates. Essentially all of the Precambrian sedimentary iron formations are of this type. The metamorphosed types also include those in which the original form of the ores has been obscured by extensive recrystallization. Some of these iron formations are important economically as iron ores because of their amenability to beneficiation by fine grinding and by concentration of the ore minerals principally by magnetic methods.
Metastable – It means a material which is not truly stable with respect to some transition, conversion, or reaction but stabilized kinetically either by rapid cooling or by some molecular characteristics as, for example, by the extremely high viscosity of polymers. It also means possessing a state of pseudo-equilibrium which has a free energy higher than that of the true equilibrium state.
Metastable beta – It is a beta-phase composition which can be partially or completely transformed to martensite, alpha, or eutectoid decomposition products with thermal or strain-energy activation during subsequent processing or service exposure.
Metastable equilibrium – It exists when additional energy is required to be introduced before the object can reach true stability.
Metastability – It is an intermediate energetic state within a dynamical system other than the system’s state of least energy. A ball resting in a hollow on a slope is a simple example of metastability. If the ball is only slightly pushed, it will settle back into its hollow, but a stronger push can start the ball rolling down the slope.
Methane – It is a chemical compound with the chemical formula CH4 (one carbon atom bonded to four hydrogen atoms). It is the simplest alkane, and the main constituent of natural gas. It is an economically attractive fuel, although capturing and storing it is difficult since it is a gas at standard temperature and pressure. It is transparent to visible light but absorbs infrared radiation, acting as a greenhouse gas. Methane is an organic compound, and among the simplest of organic compounds. Methane is also a hydrocarbon.
Methane sulphonic acid (MSA) – It is an organo-sulphuric, colourless liquid with the molecular formula CH3SO3H and structure H3C-S(=O)2-OH. It is the simplest of the alkyl-sulphonic acids (R-S(=O)2-OH). Salts and esters of methane-sulphonic acid are known as mesylates (or methane-sulphonates, as in ethyl methane-sulphonate). It is hygroscopic in its concentrated form. Methane-sulphonic acid can dissolve a wide range of metal salts, several of them in considerably higher concentrations than in hydrochloric acid (HCl) or sulfuric acid (H2SO4).
Method of measurement – It is a logical sequence of operations, described generically, used in the performance of measurements. Methods of measurement can be qualified in various ways, such as (i) substitution method, (ii) differential method, and (iii) null method.
Methylene di-aniline (MDA) – It is an organic compound with the formula CH2(C6H4NH2)2. It is a colourless solid, although commercial samples can appear yellow or brown. It is produced on an industrial scale, mainly as a precursor to polyurethanes.
Methylene diphenyl diisocyanate (MDI) – It is an aromatic diisocyanate. Three isomers are common, varying by the positions of the isocyanate groups around the rings: 2,2′-MDI, 2,4′-MDI, and 4,4′-MDI. The 4,4′ isomer is most widely used, and is also known as 4,4′-diphenylmethane diisocyanate. This isomer is also known as pure MDI. MDI reacts with polyols in the manufacture of polyurethane. It is the most produced diisocyanate.
Methyl ethyl ketone (MEK) – It is also known butanone, or ethyl methyl ketone. It is an organic compound with the formula CH3C(O)CH2CH3. This colourless liquid ketone has a sharp, sweet odour reminiscent of acetone. It is produced industrially on a large scale, but occurs in nature only in trace amounts. It is partially soluble in water, and is normally used as an industrial solvent. It is an isomer of another solvent, tetrahydrofuran.
Methyl isobutyl ketone (MIBK) – It is an organic compound with the condensed chemical formula (CH3)2CHCH2C(O)CH3. This ketone is a colourless liquid which is used as a solvent for gums, resins, paints, varnishes, lacquers, and nitrocellulose.
Methyl methacrylate (MMA) – It is an organic compound with the formula CH2=C(CH3)COOCH3. This colourless liquid, the methyl ester of methacrylic acid (MAA), is a monomer produced on a large scale for the production of poly(methyl methacrylate) (PMMA).
Metrology – It is the science of measurement. Metrology includes all aspects, both theoretical and practical, with reference to measurements, whatever their uncertainty, and in whatever fields of science or technology they occur.
‘Mf’ temperature – For an alloy system, it is the temperature at which martensite formation on cooling is essentially finished.
M-glass – It is a high beryllia (BeO2) content glass which is designed especially for high modulus of elasticity.
MHI gasifier – The Mitsubishi Heavy Industries (MHI) gasifier is based upon the Combustion Engineering air-blown slagging gasifier and co-developed between Combustion Engineering (and its subsequent owners) and Mitsubishi Heavy Industries. It has a dry feed system, suitable for low rank coals having high moisture contents. It is an air blown two-stage entrained bed slagging gasifier utilizing membrane water-wall construction.
Micelle – It is a sub-microscopic unit of structure built up from ions or polymeric molecules.
Micro – In relation to composites, it denotes the properties of the constituents, i.e., matrix, reinforcement, and interface only, and their effects on the composite properties.
Micro-alloyed steels – These are carbon-manganese steels containing deliberately added alloying elements totalling in the range of 0.05 % to 0.10 %. Alloying elements which are effective in modifying steel properties when present in such small quantities include boron, vanadium, and niobium. These steels are also sometimes called high strength low alloy (HSLA) steels. These steels are a group of low carbon steels which utilize small quantities of alloying elements to attain yield strengths higher than 275 MPa in the as-rolled or normalized condition. These steels have better mechanical properties and sometimes better corrosion resistance than as-rolled carbon steels. Also, since the higher strength of the micro-alloyed steels can be achieved at lower carbon contents, the weldability of several micro-alloyed steels is comparable to or better than that of the mild steel. A major advantage of these steels is that in the case of forgings, careful control of forge processing temperatures can eliminate subsequent heat treatment. Mechanical properties developed by controlled hot working conditions are similar to those developed by conventional hardening and tempering treatments for components where strength and toughness are needed.
Micro-alloyed ferrite-pearlite steels – These steels use additions of alloying elements such as niobium and vanadium to increase strength (and thereby increase load-carrying ability) of hot rolled steel without increasing carbon and / or manganese contents. The mechanical properties of the micro-alloyed steels result, however, from more than just the mere presence of micro-alloying elements. Austenite conditioning, which depends on the complex effects of alloy design and rolling techniques, is also an important factor in the grain refinement of hot rolled micro-alloyed steels. Grain refinement by austenite conditioning with controlled rolling methods has resulted in improved toughness and high yield strengths in the range of 345 MPa to 620 MPa. The different types of micro-alloyed ferrite-pearlite steels include (i) vanadium micro-alloyed steels, (ii) niobium micro-alloyed steels, (iii) niobium-molybdenum steels, (iv) vanadium-niobium micro-alloyed steels, (v) vanadium-nitrogen micro-alloyed steels, (vi) titanium micro-alloyed steels, (vii) niobium-titanium micro-alloyed steels, and (viii) vanadium-titanium micro alloyed steels. These steels can also include other elements for improved corrosion resistance and solid-solution strengthening, or improved hardenability (if transformation products other than ferrite-pearlite are desired).
Micro-alloying – It is a steelmaking technology in which small quantities of alloying elements (vanadium, niobium, or titanium) are used to retard recrystallization of austenite, thereby allowing a wider range of rolling temperatures for controlled rolling. Without retarding recrystallization, as in normal hot rolling, the pancake-type grains do not form and a fine grain size cannot be developed in these ferrite-pearlite steels.
Micro-alloying elements – Thses are those alloying elements which are added in small quantities singly or in combinations for refining the grain micro-structure or facilitating the precipitation hardening. Examples of microalloying elements are niobium, vanadium, titanium, molybdenum or boron.
Micro-analysis – It consists of the analysis of samples smaller than 1 milligrams.
Micro-bands – These consist of thin, sheetlike volumes of constant thickness in which cooperative slip occurs on a fine scale. These are an instability which carry exclusively the deformation at medium strains when normal homogeneous slip is precluded. The sheets are aligned at +/- 55-degree to the compression direction and are confined to individual grains, which usually contain two sets of bands.
Microbially (micro-biologically) induced corrosion (MIC) – It is corrosion which is caused by the presence and activities of micro-organisms. Micro-organisms are the organisms which cannot be seen individually with the unaided human eye, including microalgae, bacteria, and fungi. Microbially induced corrosion can cause various forms of localized corrosion, including pitting, dealloying, enhanced erosion corrosion, enhanced galvanic corrosion, stress corrosion cracking, and hydrogen embrittlement. As a result of microbially induced corrosion, corrosion can occur at locations where it is not predicted, and it can occur at very high rates. The iron and steel materials undergo microbially induced corrosion. Furthermore, microbially induced corrosion can also take place in seawater, fresh water, distilled / demineralized water, hydrocarbon fuels, process chemicals, foods, soils, human plasma, saliva, and sewage.
Micro-circuit drawing – It specifies the engineering requirements and establishes item identification for a microcircuit. It is prepared to establish the physical and functional characteristics necessary to ensure microcircuit interchangeability. It includes (i) outline and mounting requirements, (ii) performance requirements, (iii) schematic diagrams showing functional electrical elements of the microcircuit, (iv) marking requirements, (v) identification of input and output pin functions, and (vi) quality assurance provisions.
Micro combined heat and power – It is the equipment which generates process or space heat and electric power, of a size useful for a single building.
Micro-controller – It is a micro-processor which is integrated with memory and input/output circuits. Igt is useful for embedded control.
Micro-crack – It is a crack of microscopic proportions. It is also termed micro-fissure.
Micro-electro-mechanical systems (MEMS) – These are electro-mechanical systems of microscopic size. These can be sensors or actuators. Micro-electro-mechanical systems is the technology of microscopic devices incorporating both electronic and moving parts. These devices are made up of components between 1 micrometer and 100 micrometers in size. These devices normally range in size from 20 micrometers to 1 millimeter, although components arranged in arrays can be more than 1,000 square millimeters. They normally consist of a central unit which processes data (an integrated circuit chip such as microprocessor) and several components which interact with the surroundings (such as microsensors).
Micro-electronics – It consists of that part of the field of electronics which is dealing with integrated circuits.
Micro-emulsions (semi-synthetics) – Sometimes, a metal working operation needs a lubricant which provides outstanding flushing, cooling, and improved lubricating qualities. Micro-emulsions are ideal for use on galvanized, hot rolled, cold rolled, and stainless steel. Micro-emulsions provide some film strength from the combination of emulsifiers, water-soluble corrosion inhibitors, wetting agents, organic and inorganic salts, and sometimes extreme pressure agents. Micro-emulsions are emulsions in which the dispersed particles are in the range of 0.01 mm to 0.06 mm. These emulsions are usually translucent or transparent in appearance. Their small particle size provides excellent penetration and cooling for various types of metal working. Micro-emulsions can be sprayed, roller-coated or used in a flood-type coolant system.
Micro-etching – It is the development of micro-structure for microscopic examination. The normal magnification exceeds 25× (50× in some countries).
Micro-finishing grinding – It is a precision grinding process which uses extremely fine abrasive (50 micrometers and finer).
Micro-fissure – It is a crack of microscopic proportions. It is also termed micro-crack.
Micro forming – It is a technological process normally defined as the production of parts or structures with at least two dimensions in the sub-millimeter range. Most of the developments in this area have been driven by the needs of the electronics industry for mass produced miniature parts. Major challenges in micro forming fall into one of the four broad categories namely (i) material of the work piece, (ii) tooling, (iii) equipment, and (iv) process control. As an example, the flow and failure behaviour of a work-piece with only one or several grains across the section subjected to large strains can be very different from that of its poly-crystalline counterpart used in macro bulk forming processes. Micro forming operations include cold heading and extrusion of wire.
Micro-generation -It consists of small-scale electric power production to provide the needs of a small building or individual consumer.
Micro-graph – It is a graphic reproduction of the surface of a sample at a magnification greater than 25×. If produced by photographic means it is called a photo-micrograph (not a micro-photograph).
Micro-grinding – It is a precision grinding process which uses extremely fine abrasive (50 micrometers and finer).
Micro-hardness – It is the hardness of a material as determined by forcing an indenter such as a Vickers or Knoop indenter into the surface of a material under very light load, Normally, the indentations are so small that they are to be measured with a microscope. It is capable of determining hardnesses of different micro-constituents within a structure, or of measuring steep hardness gradients such as those encountered in case hardening.
Micro-hardness number – It is a commonly used term for the more technically correct term micro-indentation hardness number.
Micro-indentation – In hardness testing, it is the small residual impression left in a solid surface when an indenter, typically a pyramidal diamond stylus, is withdrawn after penetrating the surface. Typically, the dimensions of the micro-indentations are measured to determine micro-indentation hardness number, but newer methods measure the displacement of the indenter during the indentation process to use in the hardness calculation. The precise size needed to qualify as a ‘micro indentation’ has not been clearly defined. However, typical measurements of the diagonals of such impressions range from approximately 10 micrometers to 200 micrometers, depending on normal force and material.t is also the process of indenting a solid surface, using a hard stylus of prescribed geometry and under a slowly applied normal force, normally for the purpose of determining its micro-indentation hardness number.
Micro-indentation hardness number – It is a numerical quantity, normally stated in units of pressure (kilogram per square millimeter), which expresses the resistance to penetration of a solid surface by a hard indenter of prescribed geometry and under a specified, slowly applied normal force. The prefix ‘micro’ indicates that the indentations produced are typically between 10 micrometers and 200 micrometers across.
Micro-indentation hardness test – In a micro-indentation hardness test, a calibrated machine is used to force a diamond indenter of specific geometry, under a test load of 1 gram-force to 1,000 gram-force, into the surface of the test material and to measure the diagonal or diagonals optically. It is also known as micro-hardness test.
Micro-mechanics – It consists of the analysis of the structural behaviour of composites on a constituent (matrix, reinforcement, and interface) level.
Micro-mesh – It is a sieve with precisely square openings in the range of 10 micrometers to 120 micrometers produced by electro-forming.
Micro-mesh sizing – It is the process of sizing micro-mesh particles using an air or a liquid suspension process.
Micro-organisms (pathogens) – The pathogenic micro-organisms enter in to water body through sewage discharge as a major source or through the waste water from industries. Organic matter is described as bio-degradable if it is readily decomposed by the action of micro-organisms. The micro-organisms exist as a mixture of bacteria, fungi and Protozoa. In heavily polluted water, they are visible as pink, yellow, brown slimy growths which are frequently called ‘sewage funguses. The micro-organisms utilize pollutive organic compounds for their growth and nutrition and produce simple products, thereby reducing the amount of pollution. There are two types of metabolism, aerobic and anaerobic. Aerobic micro-organisms use oxygen to carry out oxidation reactions such as the (i) carbohydrates, phenols etc. are converted to carbon dioxide and water, (ii) organic nitrogen compounds are converted to carbon dioxide, water, amines and ammonia, (iii) organic sulphur compounds are converted to sulphides, and (iv) organic phosphorus compounds are converted to phosphates. Biodegradation of these compounds rapidly decreases the dissolved oxygen, and creates a biochemical oxygen demand in the polluted water. Heavily polluted water has little or no dissolved oxygen. Under these conditions only anaerobic micro-organisms can exist. Under anaerobic conditions, the anaerobic micro-organisms cause these reactions to occur namely (i) carbohydrates are converted into methane, (ii) organic sulphur compounds and sulphates are converted into sulphides, (iii) organic phosphorus compounds are converted to phosphine, (iv) organic nitrogen compounds are converted to nitrate, and then ammonia.
Micro-phone – It is a transducer which changes sound into electrical signals.
Micro-pore – It consists of the pores in a sintered product which can only be detected under a microscope.
Microporosity – It is the extremely fine porosity in castings caused by shrinkage or gas evolution, apparent on radiographic film as mottling.
Micro-porous material – It is a material containing pores with diameters less than 2 nano meters. Examples of micro-porous materials include zeolites and metal-organic frameworks.
Micro-processor – It is a computer with its logical, arithmetic and control functions implemented on one or a few integrated circuits.
Micro-pulverizer – It is a machine which disintegrates powder agglomerates by strong impacts from small hammers fastened to a solid disk which rotates at a very high velocity.
Microscope – It is a laboratory instrument used to examine objects which are too small to be seen by the naked eye. A microscope is capable of producing a magnified image of a small object. There are several types of microscopes, and they can be grouped in different ways.
Microscopic – It means being invisible to the eye unless aided by a microscope. It is visible at magnifications above 25×.
Microscopic stress – It is the residual stress in a material within a distance comparable to the grain size.
Microscopy – It is the science of investigating small objects and structures using a microscope.
Micro-segregation – All metallic materials contain solute elements or impurities which are randomly distributed during solidification. The variable distribution of chemical composition on the microscopic level in a microstructure, such as dendrites and grains, is referred to as micro-segregation. It is the segregation within a grain, crystal, or small particle. Since the micro-segregations normally deteriorate the physical and chemical properties of materials, they are to be kept to a minimum.
Micro-shrinkage – It is a casting imperfection, not detectable microspically, consisting of inter-dendritic voids. Micro-shrinkage results from contraction during solidification where the opportunity to supply filler material is inadequate to compensate for shrinkage. Alloys with wide ranges in solidification temperature are particularly susceptible.
Micro-shrinkage cavities – Micro-shrinkage cavities are aggregates of sub-surface discontinuities which are found in the cast materials. These cavities are normally found in the foundry castings close to the gate. These cavities occur if metal at the gate solidifies while some of the metal beneath is still liquid. Also, micro-shrinkage can be found deeper in the part when the liquid metal enters from the light section into heavy section where metal can solidify in the light section before the heavy section.
Micro-slip – It is small relative tangential displacement in a contacting area at an interface, when the remainder of the interface in the contacting area is not relatively displaced tangentially. Micro-slip can occur in both rolling and stationary contacts. The term micro-slip is sometimes used to denote the micro-slip velocity. This usage is not recommended.
Micro-strain – It is the strain over a gauge length comparable to inter-atomic distances. These are the strains being averaged by the macro-strain measurement. Micro-strain is not measurable by existing techniques. Variance of the micro-strain distribution can, however, be measured by X-ray diffraction.
Micro-stress – It is the residual stress in a material within a distance comparable to the grain size.
Micro-strip – It is a planar transmission line which is fabricated by printed circuit board technology and which is used for micro-wave-frequency signals.
Micro-strip antenna -It is a planar antenna which is fabricated by printed circuit board technology.
Micro-structure – It is a structure with heterogeneities which can be seen through a microscope. it is the structure of an object, organism, of material as revealed by a microscope at magnifications higher than 25×. The micro-structure of ferrous alloys is a basic tenet of physical metallurgy. The composition and processing establish the micro-structure and the micro-structure influences several properties and service behaviour of steel. For maintaining control of the quality of steel products and to diagnose problems in processing, testing, or service, the micro-structure is to be identified first and, in some cases, quantified.
Micro-void coalescence (MVC) – It is the ductile micro-mechanism of fracture which occurs because of the nucleation of microscale voids, followed by their growth and eventual coalescence. Initiation is caused by particle cracking or interfacial failure between an inclusion or precipitate particle and the surrounding matrix.
Micro-throwing power – It is the ability of a plating solution or a specified set of plating conditions to deposit metal in pores or scratches.
Micro-wave – It is a part of the radio spectrum with wavelengths shorter than 100 millimeters.
Micro-wave oven – It is a heating appliance which uses micro-wave energy.
Micro-wave radiation – It consists of electro-magnetic radiation in the wave-length range of 0.3 millimeters to 1 metre (3 million angstrom to I billion angstrom).
Micro-wave radio -It is the sub-set of radio technique using wave-lengths which are in the range of 3 giga-hertz or higher.
Micro-wave technique – This inspection technique is fairly new in its concept and whilst it has been applied in a few very specific applications in a laboratory environment. The proposed application of the technique to in-line inspection of the billets in a steel plant is thought to be unique. The detector can be mounted some tens of millimeters away from the billet surface and that must be of benefit since it reduces its susceptibility to mechanical damage. The inspection area is, however, relatively large and therefore one is to expect that it is responsive only to large area defects or to cracks of either longitudinal or transverse orientation. This form of detector shows enough merit to be considered but the capital cost of each detector head is high.
Middle-infrared radiation – It consists of infrared radiation in the wave-length range of 3 micrometers to 30 micrometers (30,000 angstroms to 300,000 angstroms).
Middling – It is a product intermediate between concentrate and tailing and containing enough of a valuable mineral to make retreatment economical.
Mid-hinge – In statistics, it is the average of the first and third quartiles and is hence is a measure of location. Equivalently, it is the 25 % trimmed mid-range or 25 % mid-summary, it is an L-estimator. The midhinge is related to the inter-quartile range (IQR), the difference of the third and first quartiles, which is a measure of statistical dispersion. The two are complementary in sense that if one knows the midhinge and the interquartile range, one can find the first and third quartiles.
Mid-range – In statistics, the mid-range is a measure of central tendency of a sample and is defined as the arithmetic mean of the maximum and minimum values of the data set. It The mid-range is closely related to the range, a measure of statistical dispersion defined as the difference between maximum and minimum values. The two measures are complementary in sense that if one knows the mid-range and the range, one can find the sample maximum and minimum values.
Midrex process – It is an ironmaking process, developed for the production of direct reduced iron (DRI). It is a gas-based shaft furnace process is a solid-state reduction process which reduces iron ore pellets or lump ore into direct reduced iron without their melting using reducing gas normally formed from natural gas. The process involves three major unit operations namely (i) iron ore reduction, (ii) gas preheating, and (iii) natural gas reforming. The heart of the Midrex process is its shaft furnace. It is a cylindrical, refractory-lined vessel and is a key component of the direct reduction process. It is flexible as well as a versatile reactor. It can use natural gas, a syngas from coal, coke oven gas, or exhaust gas from Corex process as the reducing gas. It operates at slightly above atmospheric pressure and at operating temperatures which are around 950 deg C.
MIG welding – It is metal inert-gas welding. It is a non-standard term for flux cored arc welding and gas metal arc welding.
Migmatite – It is the rock which consists of thin, alternating layers of granite and schist.
Mike mark – It is a narrow continuous line near the rolled edge caused by a contacting micro-meter.
Mil – It is one thousandth of an inch 0.001 which is equal to 25.4 micrometers. It is a unit of length used in measuring the diameter of glass fiber strands, wire, and so on.
Mild steel – It is carbon steel with a maximum of around 0.25 % carbon and containing 0.4 % to 0.7 % manganese, 0.1 % to 0.5% silicon, and some residuals of sulphur, phosphorus, and / or other elements.
Mild steel has properties which are suitable for most general engineering applications. Because of its high iron content, mild steel has excellent magnetic properties, it is hence defined as being ‘ferromagnetic’. It has a relatively higher melting point between 1,450 deg C to 1,520 deg C. This melting point means that mild steel is more ductile when heated, making it especially suitable for drilling, cutting, forging, and welding, hence easy to fabricate.
Mild wear – It is a form of wear which is characterized by the removal of material in very small fragments. Mild wear is an imprecise term, frequently used in research, and contrasted with severe wear. In fact, the phenomena studied normally involve the transition from mild to severe wear and the factors which influence this transition. Mild wear can be appreciably higher than can be tolerated in practice. With metallic sliders, mild wear debris normally consists of oxide particles.
Mill – It is a plant in which in which ore is treated and metals are recovered or prepared for smelting and also in which metals are hot worked, cold worked, or melted and cast into standard shapes suitable for secondary fabrication into commercial products. It is also a production line, normally of four or more stands, for hot or cold rolling metal standard shapes such as bar, rod, plate, sheet, or strip. It is also a single machine or hot rolling, cold rolling, or extruding metal. Examples include blooming mill, cluster mill, four-high mill, and Sendzimir mill. It is also a shop term for a milling cutter. It is also a machine or group of machines for grinding or crushing ores and other minerals. It is also a machine for grinding or mixing material, e.g., a ball mill, and a revolving drum used for the grinding of ores in preparation for treatment. It also consists of grinding or mixing a material, e.g., milling a powder metallurgy material. Common mills for the preparation of a powder are ball mill, hammer mill, disk mill, roll mill, vortex mill rod mill, and impact mill.
Mill addition – It is a material which is added to the ball milling charge of a frit.
Milled fibre – It is continuous glass strands which are hammer milled into very glass fibres. These are useful as inexpensive filler or anti-crazing reinforcing fillers for adhesives.
Mill edge – It is the normal edge produced in hot rolling of sheet metal. This edge is customarily removed when hot rolled sheets are further processed into cold rolled sheets.
Miller-Bravais indices – These are the indices used for the hexagonal system. They involve use of a fourth axis, ‘a3’, coplanar with and at 120-degree to ‘a1’ and ‘a2’.
Miller indices – It is a system for identifying planes and directions in any crystal system by means of sets of integers. The indices of a plane are related to the intercepts of that plane with the axes of a unit cell. It is the indices of a direction, to the multiples of lattice parameter which that represent the coordinates of a point on a line parallel to the direction and passing through the arbitrarily chosen origin of a unit cell.
Miller indices (for lattice planes) – These are the reciprocals of the fractional intercepts a plane makes on the three axes. The symbols are (hkl).
Miller number – It is a measure of slurry abrasivity as related to the instantaneous mass-loss rate of a standard metal wear block at a specific time on the cumulative abrasion-corrosion time curve.
Mill finish – It is a non-standard (and typically non-uniform) surface finish on mill products which are delivered without being subjected to a special surface treatment (other than a corrosion-preventive treatment) after the final working or heat-treating step.
Mill, grinding – Grinding mills are size reductions machines which frequently follow crushers in the processes where finer products are desired after crushing. Different grinding machines are normally named as mills, for example rod mills, ball mills, and attrition mills. Because of the name, verb milling is also been used as a synonym for grinding. A wide range of mills has been developed each for particular applications. Some types of mills can be used to grind a large variety of materials whereas others are used for certain specific grinding requirements/
Milling – It is sometimes also known as fine grinding, pulverizing or comminution. It is the process of reducing materials to a powder of fine or very fine size. It is distinct from crushing or granulation, which involves size reduction of a material to a smaller size. Milling is used to produce a variety of materials which either have end uses themselves or are raw materials or additives used in the manufacture of other products.
Milling circuit – It can be either open or closed. The milling circuit is the complete mill system from beginning to end, which includes feed mechanism, mill, classifier, separator, product collector, etc. In a closed mill circuit, the oversize particles are returned from the post milling processes to be regrinding, while in an open circuit the process there is no feedback loop.
Milling cutter – It is a rotary cutting tool which is provided with one or more cutting elements, called teeth, which intermittently engage the work-piece and remove material by relative movement of the work-piece and cutter.
Milling fluid, milling liquid – It is an organic liquid, such as hexane, in which ball milling is carried out. The liquid serves to reduce the heat of friction and resulting surface oxidation of the particles during grinding, and to provide protection from other surface contamination.
Milling, machining – It means removal of metal with a milling cutter.
Milling ore – It is the ore which contains sufficient valuable mineral to be treated by milling process.
Milling, powder technology – It is the mechanical comminution of a material, normally in a ball mill, to alter the size or shape of the individual particles, to coat one component of a mixture with another, or to create uniform distributions of components.
Mill lacquer – It is the organic protective coating applied to steel parts, normally pipes or tubes, to protect the parts during shipping. This material cannot be removed by the normal galvanized cleaning methods.
Millman’s theorem – It is a theorem stating the relation between branch currents and voltages for multiple sources in parallel.
Mill product – It is a commercial product of a rolling mill.
Mill protection devices – These devices ensure that the forces applied to the roll chocks are not of such a magnitude to fracture the roll necks or damage the housing.
Mill scale – It is the flaky surface of hot worked steel and is formed by the oxidation of the steel surface during reheating, conditioning, hot rolling, and hot forming operations. It is one of the wastes generated in steel plants and represents around 2 % of the produced steel. It is a hard brittle coating of several distinct layers of iron oxides formed during the processing of steel and composed mainly of iron oxides and can contain varying quantities of other oxides and spinels, elements and trace compounds. It flakes off the steel easily. Mill scale is normally present on rolled steel and is frequently mistaken for a blue-coloured primer. The very high surface temperature combined with high rolling pressures result in a smooth, bluish grey surface. Under visual inspection, mill scale appears as a black metal powder made up of small particles and chips. Its physical state is solid and powdered. The specific gravity of mill scale is in the range of 5.7 to 6.2. Mill scale’s melting point is around 1,370 deg C and boiling point is around 2,760 deg C. It has a stable state and is insoluble in water and alkalis but soluble in most of strong acids. It is normally classified as non- dangerous waste material.
Mill scale powder – It consists of pulverized iron oxide scale which is a by-product of hot working of steel (e.g., rolling, and forging). The material is readily reduced to a soft spongy iron powder free of mineral inclusions and other solid impurities.
Minable reserves – It consists of ore reserves which are known to be extractable using a given mining plan.
Mineral – It is a naturally occurring homogeneous substance having definite physical properties and chemical composition and, if formed under favourable conditions, a definite crystal form.
Mineral acid – It is also known as inorganic acid. It is an acid derived from one or more inorganic compounds, as opposed to organic acids which are acidic, organic compounds. All mineral acids form hydrogen ions and the conjugate base when dissolved in water. Commonly used mineral acids are sulphuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). These are also known as bench acids. Mineral acids range from super-acids (such as perchloric acid) to very weak ones (such as boric acid). Mineral acids tend to be very soluble in water and insoluble in organic solvents.
Mineral dressing – It is the physical and chemical concentration of raw ore into a product from which a metal can be recovered at a profit.
Mineral-insulated copper-clad cable – It is a cable with an outer metal cover and insulated by powdered inorganic material, suitable for high temperature. It is one kind of fire-resistant cable.
Mineralized material – Mineralized material is the projection of mineralization in rock based on geological evidence and assumed continuity. It may or may not be supported by sampling but is supported by geological, geochemical, geophysical or other data. This material may or may not have economically recoverable mineralization.
Mineralizer – The purpose of a mineralizer is to facilitate the transport of insoluble ‘nutrient’ to a seed crystal by means of a reversible chemical reaction. Over time, the seed crystal accumulates the material which has been once in the nutrient and grows. Mineralizers are additives which aid the solubilization of the nutrient solid. When used in small quantities, mineralizers function as catalysts. Typically, a more stable solid is crystallized from a solution which consists of a less stable solid and a solvent. The process is done by dissolution-precipitation or crystallization process.
Mineral occurrence – A Mineral occurrence is an indication of mineralization, that is worthy of further investigation. The term Mineral occurrence does not imply any measure of volume / tonnage or grade / quality and hence is not part of a Mineral resource.
Mineralogical composition and crystal formation – The behaviour of refractories of identical composition also depends on the type of raw materials used and on the reactions achieved during firing of the bricks. A glassy phase is more susceptible to attack by slag than a tightly interlocked crystal lattice structure. Two methods are used to identify mineralization composition. In the first method polarizing microscope or scanning electron microscope (SEM) is used. In the second method X-ray diffraction analysis is done.
Mineral oil – It is a liquid obtained from refining crude oil to make gasoline and other petroleum products. Mineral oils used for lubrication are known specifically as base oils. More generally, mineral oil is a transparent, colourless oil, composed mainly of alkanes and cycloalkanes, related to petroleum jelly. It has a density of around 0.8 grams per cubic centimeter to 0.87 grams per cubic centimeter. Mineral oil is a liquid mixture of hydrocarbons obtained from petroleum by intensive treatment with sulphuric and oleum, or by hydrogenation, or a combination, and consisting predominantly of saturated C15-C50 hydrocarbons.
Mineral oil based hydraulic fluids – These fluids have a mineral oil base. These fluids have high performance at lower cost. These mineral oils are further classified as HH, HL and HM fluids. Type HH fluids are refined mineral oil fluids which do not have any additives. These fluids are able to transfer power but have lesser properties of lubrication and unable to withstand high temperature. These types of fluid have a limited usage in industries. Some of the uses are manually used jacks and pumps, and low-pressure hydraulic system etc. Type HL fluids are refined mineral oils which contain oxidants and rust inhibitors which help the system to be protected from chemical attack and water contamination. These fluids are mainly used in piston pump applications. HM is a version of HL type fluids which have improved anti-wear additives. These fluids use phosphorus, zinc, and sulphur components to get their anti-wear properties. These are the fluids mainly used in the high-pressure hydraulic system.
Mineral products – Products of a mineral project can be foreseeably bought, sold or used, and can include (i) mined or produced ores, (ii) co-products, (iii) beneficiated ores, (iv) processed ore concentrates, and (v) by-products.
Mineral project – A mineral project produces mineral products from a mineral source with defined frame conditions, which provide the basis for environmental-socio-economic evaluation and decision-making. A mineral project is comprised of a defined activity or set of activities, which provide the basis for estimating environmental-socio-economic viability including costs and potential revenues associated with its implementation.
Mineral reserve – It is the economically mineable part of a measured or indicated mineral resource demonstrated by at least a preliminary feasibility study. This study is to include adequate information on mining, processing, metallurgical, economic and other relevant factors which demonstrate, at the time of reporting, that economic extraction can be justified. A mineral reserve includes diluting materials and allowances for losses that may occur when the material is mined. It includes (i) Proved Mineral reserves, which include ‘Economically mineable part of Measured Mineral resource’, and (ii) Probable Mineral reserves which include ‘Economically mineable part of indicated or in some cases a Measured Mineral resource’.
Mineral resource – A Mineral resource is a concentration or occurrence of solid material of economic interest in or on the Earth’s crust in such form, grade (or quality) that there are reasonable prospects for eventual economic extraction. The location, quantity, grade (or quality), continuity and other geological characteristics of a Mineral resource are known, estimated or interpreted from specific geological evidence and knowledge, including sampling. Mineral resources are sub divided, in order of increasing geological confidence, into Inferred, Indicated and Measured categories.
Mineral resource, indicated – It is that part of a mineral resource for which quantity, grade or quality, densities, shape and physical characteristics can be estimated with a level of confidence sufficient to allow the appropriate application of technical and economic parameters, to support mine planning and evaluation of the economic viability of the deposit. The estimate is based on detailed and reliable exploration and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough for geological and grade continuity to be reasonably assumed.
Mineral resource, measured – It is that part of a mineral resource for which quantity, grade or quality, densities, shape, and physical characteristics are so well established that they can be estimated with confidence sufficient to allow the appropriate application of technical and economic parameters, to support production planning and evaluation of the economic viability of the deposit. The estimate is based on detailed and reliable exploration, sampling and testing information gathered through appropriate techniques from locations such as outcrops, trenches, pits, workings and drill holes that are spaced closely enough to confirm both geological and grade continuity.
Mineral reserve, probable – It is the economically mineable part of an Indicated and, in some circumstances, a measured mineral resource demonstrated by at least a preliminary feasibility study. This study is to include adequate information on mining, processing, metallurgical, economic, and other relevant factors that demonstrate, at the time of reporting, that economic extraction can be justified.
Mineral reserve, proven – It is the economically mineable part of a measured mineral resource demonstrated by at least a preliminary feasibility study. This study is to include adequate information on mining, processing, metallurgical, economic, and other relevant factors that demonstrate, at the time of reporting, that economic extraction is justified.
Minerals cycle – The minerals cycle starts with the exploration and subsequent primary mineral production, such as excavation, beneficiation, processing and value-addition in a mineral project(s), as well as site decommissioning and remediation. Mineral products reflect the primary entrance of raw materials into the stock available for economic value chains. During the length of stay within value-added chains, the mineral products and compositions can be altered in linear and cyclic processes. Regardless of any sharp definition boundaries, there is an overlapping field with the Specifications for the Application of United Nations Framework Classification (UNFC) to Anthropogenic resources. The Anthropogenic resource specifications provide rules of application o United Nations Framework Classification to sources, including mine tailings, buildings, infrastructure, consumer goods, and from all the material life cycle stages, including production, use and end-of-life. Secondary minerals (including recycled material) can be used to blend primary minerals to optimize the combined value. Exploration methods used to define primary mineral sources can be utilized to classify secondary sources like mine tailings, waste rock dumps and so on. In overlapping project conditions, the choice of which document to prefer is to be based on common sense. A combination of documents can be used as well for describing the different sub-projects.
Minerals reference point – The minerals reference point is a defined physical location within the scope of a mineral project at which a reported estimate is made. The minerals reference point can be the sales, transfer, or use point of a material from the project. It can be an intermediate stage, in which case the reported quantities account for losses prior to but not subsequent to the delivery point.
Mineral silicates – It is coating for welding electrode, which provides slag and give strength to the electrode covering.
Mineral sizers – The basic concept of the mineral sizer is the use of two rotors with large teeth, on small diameter shafts, driven at a low speed by a direct high torque drive system. This design produces three major principles which all interact when breaking materials using sizer technology. The unique principles are the three-stage breaking action, the rotating screen effect, and the deep scroll tooth pattern.
Mineral sources – The term ‘source’ as used in United Nations Framework Classification is equivalent to the term deposit for minerals projects. The Glossary of Geology defines minerals as ‘a naturally occurring inorganic element or compound having an orderly internal structure and characteristic chemical composition, crystal form, and physical properties’. Mineral sources are a potentially economically recoverable accumulation of a specific or a group of minerals.
Minerals specifications – The Minerals specifications provide supplementary specifications for United Nations Framework Classification to classify mineral Projects, including metal ores, technical minerals, evaporates, aggregates and solid energy minerals such as coal and others in alignment with the Sustainable Development Goals (SDGs).
Miniature boiler – It is a fire pressure vessel which do not exceed these limits, (i) inside diameter of shell – 400 millimeters, (ii) overall length to outside of heads at centre – 1,050 millimeters, (iii) water heating surface – 1.85 square metre, or (iv) 690 kilo pascal (kPa) maximum allowable working pressure.
Mini blast furnace – Mini blast furnace is normally viewed as miniature version of the conventional large blast furnace with the internal volumes ranging from 35 cubic metres to 600 cubic metres.
Mini-mills – These mills are normally defined as steel mills which melt scrap metal /direct reduced iron to produce commodity products. Although the mini-mills are subject to the same steel processing requirements after the caster as the integrated steel plants, they differ greatly in regard to their minimum efficient size, labour relations, product markets, and management style.
Minimized spangle – It is a hot dip galvanized coating of very small grain size, which makes the spangle less visible when the part is subsequently painted.
Minimum batch size – It is the batch size for a break-even point in an economic analysis in which costs are determined as a function of units of output or volume of production. The break-even point occurs at the number of units for which the revenues equal the total costs.
Minimum bend radius – It is the minimum radius over which a metal product can be bent to a given angle without fracture.
Minimum creep rate – It is the creep rate during steady-state (linear) creep behaviour (stage II).
Minimum detectable leakage rate – It is the magnitude of the smallest leakage rate which can be unambiguously detected by a given leak detector in the presence of conditions existing at the time of test. This is normally known as sensitivity.
Minimum load (Pmin) – In fatigue, it is the least algebraic value of applied load in a cycle.
Minimum residual stress (MRS) – This term is applied to products, normally flat rolled, which have been processed to minimize internal stress of the kind that causes distortion when material is dis-proportionately removed from the two surfaces through mechanical or chemical means.
Minimum stress (Smin) – In fatigue, it is the stress which is having the lowest algebraic value in the cycle, tensile stress being considered positive and compressive stress negative.
Minimum stress-intensity factor (Kmin) – In fatigue, it is the minimum value of the stress-intensity factor in a cycle. This value corresponds to the minimum load when the load ratio is higher than 0 and is taken to be zero when the load ratio is 0.
Mining engineering – It is the engineering discipline which deals with the extraction of minerals from the ground. It is associated with several other disciplines, such as mineral processing, exploration, excavation, geology, metallurgy, geotechnical engineering and surveying. A mining engineer can manage any phase of mining operations, from exploration and discovery of the mineral resources, through feasibility study, mine design, development of plans, production and operations to mine closure.
Mining process – The process of mining starts with the discovery of an ore deposit through extraction of iron ore and finally to returning the land to its natural state. It consists of several distinct steps. The first is discovery of the ore deposit which is carried out through prospecting or exploration to find and then define the extent, location, and value of the ore body. This leads to a mathematical resource estimation of the size and grade of the deposit. Exploration and evaluation consist of identification and quantification of ore bodies by using a range of geological, geophysical, and metallurgical techniques. In its simplest forms exploration involves drilling in remote areas to sample areas. The data from exploration activities is logged, mapped, analyzed, and interpreted frequently by using models. After the ore body has been evaluated, a detailed plan for mining is developed. This detailed plan identifies which ore bodies are to be mined and in what sequence in order to deliver the required ore product at an appropriate cost. The process of mine planning is an important step before the start of mine development and it continues on day-to-day basis once the mine becomes operational. To gain access to the ore deposit within an area, it is frequently necessary to mine through or remove waste material (also known as overburden) which is not of an interest. The total movement of ore and waste constitutes the mining process. Frequently, more waste than ore is mined during the life of a mine, depending on the nature and location of the ore deposit. Removal and placement of overburden is a major cost in the mining operation. Mining of the ore can be done either by surface mining, or by underground mining depending on the nature of the deposit. Underground mining includes the use of tunnels or vertical shafts to obtain ore from below earth’s surface. These shafts can penetrate down into the ground or sideways below the earth.
Mining projects – A mining project produces mineral products from a mineral source with defined frame conditions, which provide the basis for environmental-socio-economic evaluation and in decision-making. The project is comprised of a defined activity or set of activities, which provide the basis for estimating technical viability on the one hand (F-axis issues) and environmental-socio-economic viability, on the other (E-axis issues). In United Nations Framework Classification, a project can have quantities in several classes (i.e., reflecting products which are to be sold or used, products which are to be consumed by the project or not used (e.g., fuel and mine tailings) and quantities which are not to be associated with any project (e.g., unrecoverable quantities remaining in situ). In addition, a project can produce multiple products, defined as the quantities crossing the reference points through sub-projects which may or may not have the same categories.
Mining report – A Mining report is understood as the current documentation of the state of development and exploitation of a deposit during its economic life including current mining plans. It is normally made by the operator of the mine. The study takes into consideration the quantity and quality of the minerals extracted during the reporting time, changes in the Economic Viability categories because of changes in prices and costs, development of relevant technology, newly imposed environmental or other regulations, and data on exploration conducted concurrently with mining. It presents the current status of the deposits, providing a detailed and accurate, up-to-date statement on the reserves and the remaining resources.
Minor injury – It is the injury other than a fatality or a lost time injury or minor treatment injury (MTI) which is treated by first aid or minor manipulation to provide relief for a strain or bruise. A minor injury does not need treatment by a professionally trained paramedic or physician and does not incur loss of work time other than time of shift on which it occurred. The injured person continues with his normal scheduled work.
Minor treatment injury (MTI) – It is injury other than a fatality or lost time injury, which is treated by a paramedic or a physician without loss of work time other than time of the shift on which it occurred, and the injured person continues with his normal scheduled work.
Minus mesh – It is the portion of a powder sample which passes through a screen of stated size.
Minus sieve – It is the portion of a powder sample which passes through a standard sieve of a specified number.
Mirror-finish grinding – It is a class of grinding processes in which extremely fine abrasive particles are used to achieve reflective surfaces of precise geometry. These methods are used in finishing such items as moulds and dies which are used for making contact lenses and optical components.
Mirror illuminator – It is a thin, half-round opaque mirror interposed in a microscope for directing an intense oblique beam of light to the object. The light incident on the object passes through one half of the aperture of the objective, and the light reflected from the object passes through the other half aperture of the objective.
Mirror region (ceramics, glassy materials) – It is the comparatively smooth region which symmetrically surrounds a fracture origin. The mirror region ends in a microscopically irregular manner at the beginning of the mist region.
Miscellaneous couplings – These couplings get their flexibility from a combination of the mechanisms described above or through a unique mechanism like spring couplings.
Misch-metal – It is a natural mixture of rare-earth elements (atomic numbers 57 through 71) in metallic form. It contains around 50 % cerium, the remainder being principally lanthanum and neodymium.
Miscibility – It is the property of two substances to mix in all proportions (i.e., to fully dissolve in each other at any concentration), forming a homogeneous mixture (a solution). Such substances are said to be miscible (etymologically equivalent to the common term ‘mixable’). The term is most frequently applied to liquids but also applies to solids and gases. An example in liquids is the miscibility of water and ethanol as they mix in all proportions.
Miscibility gap – It is a region in a phase diagram for a mixture of components where the mixture exists as two or more phases i.e., a region of composition of mixtures where the constituents are not completely miscible. The miscibility gap is defined as ‘Area within the coexistence curve of an isobaric phase diagram (temperature vs composition) or an isothermal phase diagram (pressure vs composition)’. A miscibility gap between isostructural phases can be described as the solvus, a term which is also used to describe the boundary on a phase diagram between a miscibility gap and other phases. Thermo-dynamically, miscibility gaps indicate a maximum (e.g., of Gibbs energy) in the composition range.
Mismatch – It is the misalignment or error in register of a pair of forging dies. It is also applied to the condition of the resulting forging.
Misplaced core – It is an irregularity of wall thickness, e.g. one wall thicker than the other. It is caused by core out-of- alignment, careless coring-up and closing of mould, or rough handling after the mould is closed.
Misrun – It is a casting not fully formed because of solidification of metal before the mould is filled. It denotes an irregularity on a cast metal surface which is caused by incomplete filling of the mould because of the low pouring temperatures, gas back pressure from inadequate venting of the mould, and inadequate gating.
Missing at random – It is said of missing data when the probability of being missing on a variable is unrelated to the value of that variable had it been observed.
Missing data – It is the problem of data being absent for one or more variables in one’s study.
Mission statement – It is more concrete than vision statement and is specific to the competitive advantage of the organization. It is used to prioritize the organizational activities. There are several benefits of a well-conceived and well-constructed mission statement. Mission statement is not optional. It is crucial that every organization, regardless of size or industry, make a concerted effort to study, develop, codify, and institutionalize a strategic mission statement. Mission is an assumed responsibility of the organization born from its social goals. Mission reflects the way in which vision can be transformed into a tangible existence for the organization. In other words, the organization exists since it creates value for the customers and satisfies their needs. The mission of the organization represents the reason for existence and for creating value for the organization. It synthesizes the existential law of the organization and explains its vision. The mission typically describes what the organization does to achieve its vision.
Mismatch – It is the misalignment or error in register of a pair of forging dies. It is also applied to the condition of the resulting forging. The acceptable quantity of this displacement is governed by blueprint or specification tolerances. Within tolerances, mismatch is a condition; in excess of tolerance, it is a serious defect. Defective forgings can be salvaged by hot-reforging operations.
Mist – It is the suspension of liquid droplets formed when a finely divided liquid is suspended in the air, with a size ranging from 0.01 micrometers to 100 micrometers. Mists are generated in several processes. Mist is considered to be the main aerosol which is generated in the wet processes. Mist remains suspended in the air and has serious consequences on worker health and the environment.
Mistake minimization – It is a process utilized in design to minimize mistakes on system elements for which satisfactory design experience is available. The process involves rigorous application of standards and computerized design methods, reuse of successful designs where possible, and root-cause analysis to eliminate problems from prototypes.
Mist hackle (ceramics, glassy materials) – It consists of markings on the surface of a crack accelerating close to the effective terminal velocity, observable first as a mist on the surface and, with increasing velocity, revealing a fibrous texture elongated in the direction of cracking and coarsening up to the stage at which the crack bifurcates. Velocity bifurcation or velocity forking is the splitting of a single crack into two mature diverging cracks at or near the effective terminal velocity of approximately half the transverse speed of sound in the material.
Mist lubrication – It is the lubrication by an oil mist produced by injecting oil into a gas stream.
Mitchell bearing – It is a pad bearing in which the pads are free to take up a position at an angle to the opposing surface as per the hydrodynamic pressure distribution over its surface.
Mitigation – Mitigation consists of factors or events which can prevent a hazard escalating to an accident, or can reduce the likelihood or severity of an accident. Mitigation can be provided by a number of means including engineered systems, procedures and providence i.e. ‘good luck’.
Mixed‐bed drying – Mixed bed drying is a process of evaporative drying. The drying of the lignite coal is carried out in circulating fluidized bed where the hot bed material supplies heat for drying. Drying off‐gas is water vapour which is easy to be recovered and utilized. The drying off‐gas is cyclic utilization with heat transfer taking place in drying chamber where lignite coal gets dried.
Mixed grain size – It means the simultaneous presence of two grain sizes in substantial quantities, with one grain size appreciably larger than the others.
Mixed liquor – In the activated sludge process, it is the fluid which results by blending settled primary wastewater or equalized influent with a culture of micro-organisms. This mixed liquor is passed through an aeration tank which provides an adequate oxygen rich environment for the microbes to eat and stabilize the organic matter in water.
Mixed lubrication – The film thickness in thick-film lubrication can be reduced by (i) decrease of the viscosity (e.g. owing to temperature rise), (ii) decrease of the sliding speed, or (iii) increase of the load. The surfaces become close to each other and the normal load between the metal working tool and the work piece is supported partly by metal-to-metal contact of the surfaces and partly by the fluid film in hydrodynamic pockets in the surface roughness of the interfaces. This is usually referred to as mixed lubrication and also as the thin film or quasi-hydrodynamic regime. The film thickness is lower than three times of the surface roughness. The coefficient of friction can be as high as about 0.4 (hence, forces and power consumption can increase considerably), and wear can be significant. There is an optimum roughness for effective lubricant entrapment, with a recommended roughness of commonly 15 microns. The hydrodynamic pockets also serve as reservoirs for supplying lubricant to those regions at the interface which are starved for lubricants.
Mixed oxide (MOX) fuel – It is a blend of oxides of plutonium and natural uranium, reprocessed uranium, or depleted uranium which behaves similarly (though not identically) to the low enriched uranium feed for which many nuclear reactors are designed. Mixed oxide fuel is an alternative to low enriched uranium fuel used in the light water reactors which predominate nuclear power generation.
Mixed potential – It is the potential of a sample (or samples in a galvanic couple) when two or more electro-chemical reactions are occurring. It is also called galvanic couple potential.
Mixed variable – Some variables are between being categorical and numerical. For example, daily rainfall is exactly zero on all dry days, but is a continuous variable on rainy days. Wind speed is similar, with zero being calm. Frequently there is a single ‘special value’, here zero, and otherwise the variable is continuous. This is not always the case. For example, sunshine hours expressed as a fraction of the day length, is zero on cloudy days and 1 (or 100 %) on days with no cloud (or haze). In the analysis it is normal to treat the categorical and the numerical parts separately. However, categorical variables are normally summarized using frequencies and percentages.
Mixing, mix – In powder metallurgy, it is the thorough intermingling of powders of two or more different materials. It is not to be confused with blending.
Mixing chamber – It is that part of a welding or cutting torch in which a fuel gas and oxygen are mixed.
Mixture – It is a material made up of two or more different substances which are mixed physically but are not combined chemically (i.e. a chemical reaction has not taken place which has changed the molecules of the substances into new substances).A mixture has two or more components which are thoroughly intermingled by mixing.
Mobile crane – Mobile crane is mounted on a carrier normally a truck which provides the mobility for the crane. This crane has two parts namely (i) a carrier which is frequently referred to as the ‘lower’ and (ii) a lifting component which includes the boom also referred to as the ‘upper’. These are mated together through a turntable which allows the upper to swing from side to side. The present-day hydraulic truck cranes are normally single engine machines, with the same engine powering the under-carriage and the crane. The upper is normally powered through hydraulics run through the turntable from the pump mounted on the lower. Earlier the hydraulic truck cranes had two engines. One in the lower is used for the crane to travel on the road and ran a hydraulic pump for the outriggers and jacks. The second in the upper ran the upper through a hydraulic pump of its own.
Mobile phase – In chromatography, it is the gas or liquid which flows through the chromatographic column. It is a sample compound in the mobile phase which moves through the column and is separated from compounds residing in the stationary phase.
Mobile phone – It is a handset which connects to the public switched telephone network by radio.
Modbus – It is a brand name for a serial protocol for industrial control equipment communication.
Mode – It is one of the three classes of crack (surface) displacements adjacent to the crack tip. These displacement modes are associated with stress and strain fields around the crack tip and are designated ‘I’ (opening mode), ‘II’ (in-plane shear), and ‘III’ (out-of-plane shear, torsion). In reliability-centered maintenance, mode is the total collection of a set of events that are likely to cause a failed state. In statistics, it is the most commonly occurring value in a distribution. It is the most common or most probable value observed in a set of observations or sample.
Model, engineering – Model comes after the drawings. It is made for the project and it personify how the project is going to look when it is complete. The benefit of making model is that it helps the engineers in identifying the difficulties. Everything is clear in a model, the design, elevation, as well as internal and external detailing. The engineering model is represented by a collection of predefined parameterized engineering drawings of mechanical parts, while the graph model is derived from the engineering model with different level of detailsIn automation, model serves as a blueprint for the automated process, defining the sequence of activities, the conditions under which they occur, and the resources required.
Modelling – It consists of the use of computers to simulate a physical system. Computers perform the numerical analysis and frequently graphically display the results.
Modelling and simulation (M&S) – It is the use of models (e.g., physical, mathematical, behavioural, or logical representation of a system, entity, phenomenon, or process) as a basis for simulations to develop data utilized for managerial or technical decision making. In the computer application of modelling and simulation a computer is used to build a mathematical model which contains key parameters of the physical model. The mathematical model represents the physical model in virtual form, and conditions are applied that set up the experiment of interest. The simulation starts, i.e., the computer calculates the results of those conditions on the mathematical model, and outputs results in a format which is either machine-readable or human-readable, depending upon the implementation.
Model, mathematical – It is a mathematical description of the physical behaviour underlying a manufacturing process which is used to predict performance of the process in terms of operating parameters. Very frequently process models are reduced to software and are manipulated with computers.
Model, process – It is a graphical or mathematical representation of a process. It includes all the steps, activities, or tasks involved in the process, the sequence in which they occur, and the relationships between them.
Model, statistical – In statistical analysis, the word ‘model’ is used in several ways and means different things, depending on the discipline. Statistical models form the bedrock of data analysis. A statistical model is a simple description of a process which can have given rise to observed data. A model is a formal expression of a theory or causal or associative relationship between variables, which is regarded by the analyst as having generated the observed data. A statistical model is always a simplified expression of a more complex process, and hence, the analyst is to anticipate some degree of approximation a priori. A statistical model which can explain the greatest amount of underlying complexity with the simplest model form is preferred to a more complex model. There are several probability distributions which are key parts of models in statistics, including the normal distribution and the binomial distribution.
Model predictive control – It is a control strategy for process systems based on a mathematical model of the process and its disturbances.
Modem – It means modulator-demodulator which is an interface between a computer system and a telephone network.
Moderator – It is a substance which slows neutrons down in a ‘thermalʼ reactor to enable fission to take place. The term ‘thermal’ refers to the energy of the neutrons after moderation (slowing).
Modes – It is the three classes of crack (surface) displacements adjacent to the crack tip. These displacement modes are associated with stress-strain fields around the crack tip and are designated class I, class II, and class III and represent opening, sliding, and tearing displacements respectively.
Modification – It is the treatment of molten hypoeutectic (8 % to 13 % silicon) or hypereutectic (13 % to 19 % silicon) aluminum-silicon alloys for improving the mechanical properties of the solid alloy by refinement of the size and distribution of the silicon phase. It involves additions of small percentages of sodium, strontium, or calcium (hypoeutectic alloys) or of phosphorus (hypereutectic alloys).
Modified ASTM acetic acid salt intermittent spray (MASTMAASIS) test – It is used to predict the alloy system’s exfoliation corrosion (EFC) susceptibility.
Modified parabolic flow characteristic – It is an inherent flow characteristic which provides equal percentage characteristic at low closure member travel and around a linear characteristic for upper portions of closure member travel.
Modifying factors – These are considerations used to convert Mineral resources to Ore reserves. These include, but are not restricted to, mining, processing, metallurgical, infrastructure, economic, marketing, legal, environmental, social and governmental factors.
Modular structure automation – Modular structure automation brings an agility and flexibility to production never before seen. It brings a completely new way of thinking by subdividing process line tasks into smaller, more manageable building blocks. By acting like building blocks, the modules can be replicated and used to number up or number down in order meet rapidly changing capacity demands. By simply changing a few modules, a completely new product can be produced. Highly developed standard solutions make it easy to implement logic and communication to external systems.
Modulation – It is the impression of information on a carrier wave for transmission.
Modulation transformer – It is part of a radio transmitter which is used to impress modulation on one amplifying stage.
Modulus, initial – It is the slope of the initial straight portion of a stress-strain or load-elongation curve.
Modulus of elasticity (E) – It is the measure of rigidity or stiffness of a material. It is the ratio of stress, below the proportional limit, to the corresponding strain. If a tensile stress of 13.8 MPa results in an elongation of 1 %, the modulus of elasticity is 13.8 MPa divided by 0.01, or 1,380 MPa. In terms of the stress-strain curve, the modulus of elasticity is the slope of the stress-strain curve in the range of linear proportionality of stress to strain. It is also known as Young’s modulus. For materials which do not conform to Hooke’s law throughout the elastic range, it is the slope of either the tangent to the stress-strain curve at the origin or at low stress, the secant drawn from the origin to any specified point on the stress-strain curve, or the chord connecting any two specific points on the stress-strain curve is normally taken to be the modulus of elasticity. In these cases, the modulus is referred to as the tangent modulus, secant modulus, or chord modulus, respectively.
Modulus of resilience – It is the quantity of energy stored in a material when loaded to its elastic limit. It is determined by measuring the area under the stress-strain curve up to the elastic limit.
Modulus of rigidity – It is the ratio of shear stress to the corresponding shear strain for shear stresses below the proportional limit of the material. Values of modulus of rigidity are normally determined by torsion testing. It is also known as shear modulus.
Modulus of rupture – It is the nominal stress at fracture in a bend test or torsion test. In bending, modulus of rupture is the bending moment at fracture divided by the section modulus. In torsion, modulus of rupture is the torque at fracture divided by the polar section modulus.
Modulus of rupture (MOR), Modulus of deformation (refractories) – During thermal stress, normally combined with altered physical-chemical conditions because of infiltration, strain conditions occur in refractory brickwork which can lead to brick rupture or crack formation. In order to determine the magnitude of rupture stress, the resistance to deformation under bending stress (rupture strength) is measured. Determination of the modulus of deformation in the cold state is carried out, together with modulus of rupture, on a test bar resting on two bearing edges. In general, a high ductility is looked for in refractory bricks,i.e. a large deformation region without rupture, which means a high value of the ratio of modulus of rupture to modulus of deformation. The modulus of rupture is defined as the maximum stress of a rectangular test piece of specific dimensions which can withstand maximum load until it breaks, expressed in MPa.
Modulus of rupture in bending (Sb) – It is the value of maximum tensile or compressive stress (whichever causes failure) in the extreme fibre of a beam loaded to failure in bending computed from the flexure equation ‘Sb = Mc/I’, where ‘M’ is maximum bending moment, computed from the maximum load and the original moment arm, ‘c’ is the initial distance from the neutral axis to the extreme fibre where failure occurs, and ‘I’ is the initial moment of inertia of the cross section about the neutral axis.
Modulus of rupture in torsion (Ss) – It is the value of maximum shear stress in the extreme fibre of a member of circular cross section loaded to failure in torsion computed from the equation ‘Ss = Tr/J’, where ‘T’ is maximum twisting moment, ‘r’ is original outer radius, and ‘J’ is the polar moment of inertia of the original cross section.
Modulus of toughness – It is the quantity of work per unit volume of a material needed to carry that material to failure under static loading.
Modulus, secant – It is idealized Young’s modulus derived from a secant drawn between the origin and any point on a non-linear stress-strain curve. On materials whose modulus changes with stress, the secant modulus is the average of the zero applied stress point and the maximum stress point being considered.
Modulus, tangent – It is the slope of the line at a pre-defined point on a static stress-strain curve, expressed in force per unit area per unit strain. This is the tangent modulus at that point in shear, tension, or compression, as the case may be.
Mohs hardness – Mohs hardness is defined by how well a substance will resist scratching by another substance. It is rough measure of the resistance of a smooth surface to scratching or abrasion, expressed in terms of a scale devised by the German mineralogist Friedrich Mohs in 1812. The Mohs hardness of a mineral is determined by observing whether its surface is scratched by a substance of known or defined hardness. To give numerical values to this physical property, minerals are ranked along the Mohs scale, which is composed of 10 minerals that have been given arbitrary hardness values. These minerals, in decreasing order of hardness, are diamond -10, corundum – 9, topaz – 8, quartz – 7, othoclase (feldspar) – 6, apatite – 5, fluorite – 4, calcite – 3, gypsum – 2, and talc – 1.
Mohs hardness test – It is a scratch hardness test for determining comparative hardness using 10 standard minerals, from talc (the softest) to diamond (the hardest).
Moire pattern – It consists of a pattern developed from interference or light blocking when gratings, screens, or regularly spaced patterns are superimposed on one another.
Moiety – It is a portion of a molecule, normally complex, having a characteristic chemical property.
Moisture – It is the water in the liquid or vapour phase.
Moisture absorption – It is the pickup of water vapour from air by a material. It relates only to vapour withdrawn from the air by a material and is to be distinguished from water absorption, which is the gain in weight because of the take-up of water by immersion.
Moisture content – It is the quantity of moisture in a material determined under prescribed conditions and expressed as a percentage of the mass of the moist sample, i.e, the mass of the dry substance plus the moisture present.
Moisture equilibrium – It is the condition reached by a sample when it no longer takes up moisture from, or gives up moisture to, the surrounding environment.
Moisture vapour transmission (MVT) – It consists of a rate at which water vapour passes through a material at a specified temperature and relative humidity.
Moisture in steam – It consists of particles of water carried in steam, expressed as the percentage by weight.
Moisture loss – It is the boiler flue gas loss representing the difference in the heat content of the moisture in the exit gases and that at the temperature of the ambient air.
Molality – It is the number of gram-molecular weights of a compound dissolved in 1 litre of solvent.
Molarity – It is the number of gram-molecular weights of a compound dissolved in 1 litre of solution.
Molar mass – It is defined as the mass of a given substance divided by the quantity of the substance, and is expressed in grams per mol (g/mol). This makes the molar mass an average of several particles or molecules (potentially containing different isotopes), and the molecular mass the mass of one specific particle or molecule. The molar mass is normally the more appropriate quantity when dealing with macroscopic (weigh-able) quantities of a substance.
Molal solution – It is the concentration of a solution expressed in moles of solute divided by 1,000 grams of solvent.
Molar solution – It is the aqueous solution which contains 1 mole (gram-molecular weight) of solute in 1 litre of the solution.
Mole – One mole is the mass numerically equal (in grams) to the relative molecular mass of a substance. It is the quantity of substance of a system which contains as many elementary units (6.02 × 10 to the power 23) as there are atoms of carbon in 0.012 kilograms of the pure nuclide 12 carbon, the elementary unit is to be specified and can be an atom, molecule, ion, electron, photon, or even a specified group of such units.
Molecular-beam epitaxy (MBE) – It is an epitaxy method for thin-film deposition of single crystals. Molecular beam epitaxy is a vacuum deposition process which is used to form epitaxial films on semi-conductor materials and in the manufacture of semiconductor devices, including transistors. Molecular-beam epitaxy is used to make diodes and MOSFETs (MOS field-effect transistors) at micro-wave frequencies, and to manufacture the lasers used to read optical discs (such as compact disks and digital video disks).
Molecular emission – The energetic emitting volume of a spectroscopic source can contain small molecules in addition to free atoms. Like the atoms, the molecules produce optical emission which reflects change in the energies of the outer electrons of the molecule. Unlike the atoms, the molecules have numerous vibrational and rotational levels associated with each electronic state. Each electronic transition in the molecule produces an emission band composed of individual lines reflecting the vibrational and rotational structure of the electronic states involved in the transition. Molecular bands appear in a recorded spectrum as intense edges, out of which develop at higher or lower wave-lengths less intense lines with a spacing which increase with distance from the edge. The edge is the band head. Composed of many closely spaced lines, molecular bands can dominate a region of the spectrum, complicating detection of emission from other species in that region. Emission sources are frequently designed to minimize molecular emission. Less frequently, band intensities are used in place of atomic line intensities to measure concentration.
Molecular flow – It prevails in the high and ultra-high vacuum ranges. In these regimes the molecules can move freely, without any mutual interference. Molecular flow is present where the mean free path length for a particle is very much larger than the diameter of the pipe.
Molecular fluorescence spectroscopy – It is an analytical technique which measures the fluorescence emission characteristic of a molecular, as opposed to an atomic, species. The emission results from electronic transitions between molecular states and can be used to detect and / or measure trace amounts of molecular species.
Molecular formula – Molecular formulae simply indicate the numbers of each type of atom in a molecule of a molecular substance. They are the same as empirical formulae for molecules that only have one atom of a particular type, but otherwise can have larger numbers. An example of the difference is the empirical formula for glucose, which is CH2O (ratio 1:2:1), while its molecular formula is C6H12O6 (number of atoms 6:12:6). For water, both formulae are H2O. A molecular formula provides more information about a molecule than its empirical formula, but is more difficult to establish.
Molecular mass – It is the mass of a given molecule. Units of daltons (Da) are frequently used. Different molecules of the same compound can have different molecular masses since they contain different isotopes of an element. The derived quantity relative molecular mass is the unitless ratio of the mass of a molecule to the atomic mass constant (which is equal to one dalton). The molecular mass and relative molecular mass are distinct from but related to the molar mass.
Molecular orbital (MO) – It is a region in which one or more electrons can be found in a molecule (as opposed to that within an individual atom).
Molecular seal – It is a seal which is basically of the wind back type, but that is used for sealing vapours or gases. Because of this use, the grooves and lands are dimensioned differently from those of a wind-back seal.
Molecular spectrum – It consists of the spectrum of electro-magnetic radiation emitted or absorbed by a collection of molecules as a function of frequency, wave number, or some related quantity.
Molecular structure – It is the manner in which electrons and nuclei interact to form a molecule, as elucidated by quantum mechanics and the study of molecular spectra.
Molecular weight – It consists of the sum of the atomic weights of all the atoms in a molecule. Atomic weights (and hence molecular weights) are relative weights arbitrarily referred to an assigned atomic weight of exactly 12.0000 for the most abundant isotope of carbon, 12 carbon. The definition of molecular weight is most authoritatively synonymous with relative molecular mass. However, in common practice, use of this terminology is highly variable. When the molecular weight is given with the unit Da, it is frequently as a weighted average similar to the molar mass but with different units. The terms molecular mass, molecular weight, and molar mass can be used interchangeably in less formal contexts where unit-correctness and quantity-correctness is not needed. The molecular mass is more commonly used when referring to the mass of a single or specific well-defined molecule and less commonly than molecular weight when referring to a weighted average of a sample. In case of composites, it is the sum of the atomic weights of all the atoms in a molecule. A measure of the chain length for the molecules whih make up the polymer.
Molecule – It is the smallest portion of a substance which can exist by itself and retain the properties of the substance. Molecules consist of multiple atoms and a particular molecule has a specific number of atoms arranged in a specific way. For example, water is a molecule consisting of two hydrogen atoms and one oxygen atom, the hydrogen atoms are bound to opposite sides of the oxygen atom with an angle of around 104.5-degree between the two hydrogen atoms. A molecule can be thought of either as a structure built of atoms bound together by chemical forces or as a structure in which two or more positively charged nuclei are maintained in some definite geometrical configuration by attractive forces from the surrounding cloud of electrons. Besides chemically stable molecules, short-lived molecular fragments termed free radicals can be observed under special circumstances.
Mollier diagram – It is the thermodynamic phase diagram for water / steam. The Mollier diagram is a small portion of data from the steam tables graphed onto enthalpy-entropy coordinates.
Molten metal flame spraying – It is a thermal spraying process variation in which the metallic material to be sprayed is in the molten condition.
Molten salt baths – These are anhydrous, fused chemical baths used at high temperatures for a variety of industrial cleaning applications. Among the more common uses of these baths include (i) removal of organic polymers and coatings, (ii) dissolution of sand, ceramic, and glassy materials, and (iii) stripping of plasma carbide coatings. In addition, molten salt baths may be used to pretreat cast iron surfaces before brazing and bonding operations. Molten salt baths for cleaning applications are chemically active or reactive fluids with unique process capabilities. They are quite distinct from other molten salt compositions which are used for simple heat transfer or heat treatment applications. Equipment requirements for successful use of these processes also differ from molten salt heat transfer or heat treatment equipment. Larger volumes of insoluble cleaning by-products are normally formed which are to be effectively and safely collected and removed from the baths.
Molten weld pool – It is the liquid state of a weld prior to solidification as weld metal.
Molybdenum – It is a chemical element. it has symbol Mo and atomic number 42. It is carbide former, and prevents brittleness. It maintains the steel strength at high temperatures. It is present in several steels. Air-hardening steels always have 1 % or more of molybdenum. Molybdenum provides the ability in steel to harden in air. It adds greatly to the penetration of hardness and increases toughness of an alloy steel. It causes steel to resist softening at high temperatures, which defeats the purpose of hot working. If the alloy steel has below 0.02 % molybdenum, then steel can be hot worked with little difficulty. It is used very widely because of its powerful effect in increasing hardenability and also because in low alloy steels, it reduces susceptibility to temper brittleness. It forms stable carbides, raises the temperature at which softening takes place on tempering, and increases resistance to creep. In high-speed steel, it can be used to replace around twice its weight of tungsten. The corrosion resistance of stainless steel is improved by the addition of molybdenum.
Moment – It is an expression which involves the product of a distance and a physical quantity such as a force or electric charge. Moments are normally defined with respect to a fixed reference point and refer to physical quantities located some distance from the reference point
Moment of inertia – Moment of inertia of a rigid body is defined relative to a rotational axis. It is the ratio between the torque applied and the resulting angular acceleration about that axis. It plays the same role in rotational motion as mass does in linear motion. A body’s moment of inertia about a particular axis depends both on the mass and its distribution relative to the axis, increasing with mass and distance from the axis.
Momentum – It is the product of the mass and velocity of an object. It is a vector quantity, possessing a magnitude and a direction.
Monatomic – It is a combination of the words namely ‘mono’ and ‘atomic’, and means ‘single atom’. It is normally applied to gases. A monatomic gas is a gas in which atoms are not bound to each other. Examples at standard conditions of temperature and pressure include all the noble gases (helium, neon, argon, krypton, xenon, and radon), though all chemical elements will be monatomic in the gas phase at sufficiently high temperature (or very low pressure). The thermodynamic behavior of a monatomic gas is much simpler when compared to polyatomic gases because it is free of any rotational or vibrational energy.
Mond process – It is a process for extracting and purifying nickel. The main features consist of forming nickel carbonyl by reaction of finely divided reduced metal with carbon mono-oxide, then decomposing the nickel carbonyl to deposit purified nickel on small nickel pellets.
Monel alloys – Monel are a group of alloys of nickel (from 52 % to 67 %) and copper, with small quantities of iron, manganese, carbon, and silicon. Monel alloys are also known as Monel metal. Monel alloys are not cupro-nickel alloys since they have less than 60 % copper. Monel alloys are mainly nickel-copper alloys. There are several types of Monel alloys. The present popular grades are Monel alloy 400, Monel alloy 405, and Monel alloy 500. Monel alloy 400 is also known as ‘Historic Monel’ and ‘alloy 400’.
Monitoring – It is the systematic and continuous collection and analysis of information about the progress of a development intervention. Monitoring is done to ensure that all the people who need to know about an intervention are properly informed, and so that decisions can be taken in a timely manner. In a nuclear facility, it is the measurement of radiation levels, concentrations, surface area concentrations or quantities of radioactive material and the use of the results of these measurements to evaluate potential exposures and doses.
Monitoring approach – Under this approach, process parameters and specific consumption at each point of the process is closely monitored to ensure that it does not go off the norms for a long period. In case of notice of any deviation, corrective actions are taken to bring back the process parameters and the specific consumption within the norm. This approach adopts the real time monitoring of the consumption through a centralized control centre.
Monitoring of energy consumption – Continuous monitoring of the energy at various processes has a positive effect on the energy conservation efforts. This monitoring indicates where the process is going off the normal and timely corrective action to bring the process back to normal has a very positive effect towards the energy conservation. These days supervisory control and data acquisition (SCADA) system is used for the energy monitoring. SCADA system gathers all plant site energy information and manages the load dispatch. Energy information to SCADA system is provided by remote PLCs and field instruments. Energy management optimization tools are used for high performance energy process data management and for the recording of time series – both historic and forecasts- of measured and calculated data. For this real time process data is collected from various data acquisition systems through interfaces and stored in the database as time histories.
Monitoring of exposure – It is the systematic measurement of exposure to work related health hazards from, for instance, chemical substances, noise, vibration, or radiation.
Monitoring process – It encompasses a range of activities aimed at improving the operational efficiency by tracking, analyzing, and evaluating key parameters within the organization. The extent to which it is then operationalized depends on the appropriate decision-making by the persons who are level of BPM maturity in the organization.
Mono-chromatic (homogeneous) – It means of the same wave-length.
Mono-chromatic – It consists of electromagnetic radiation having a single wavelength or an extremely small range
of wave-lengths, or particles having a single energy or an extremely small range of energies.
Mono-chromator – It is a device for isolating mono-chromatic radiation from a beam of poly-chromatic radiation.
Mono-chromatic objective – It is an objective, normally of fused quartz, which has been corrected for use with mono-chromatic light only.
Monoclinic – It means having three axes of any length, with two included angles equal to 90-degree and one included angle not equal to 90-degree.
Mono-ethanol-amine (MEA) – It is a naturally occurring organic chemical compound with the formula HOCH2CH2NH2 or C2H7NO. The molecule is bifunctional, containing both a primary amine and a primary alcohol. It is a colourless, viscous liquid with an odour reminiscent of ammonia.
Mono-filament – It is a single fibre or filament of indefinite length, strong enough to function as a yarn in commercial textile operations.
Mono-layer – It is the basic laminate unit from which cross-plied or other laminate types are constructed. It is also, a ‘single’ layer of atoms or molecules which is adsorbed on or applied to a surface.
Monolithic micro-wave integrated circuit – It is an integrated circuit which operates in micro-wave frequencies and which can be fabricated by printed circuit board technology.
Monolithic refractories – Monolithic refractories are special mixes or blends of dry granular or cohesive plastic materials used to form virtually joint free linings. They are unshaped refractory products which are installed as some form of suspension that ultimately harden to form a solid mass. Most monolithic formulations consist of large refractory particulates (an aggregate), fine filler materials (which fill the inter particle voids) and a binder phase (that gels the particulates together in the green state). Types of these refractories are castable refractories, insulating castables, plastic refractories, ramming mixes, patching refractories, coating refractories, mortars, gunning and fettling mixes etc. Monolithic refractories represent a wide range of mineral compositions and vary greatly in their physical and chemical properties. Some are low in refractoriness while others approach high purity brick compositions in their ability to withstand severe environments. Various means are employed in the placement of monolithic refractories like ramming, casting, guniting, spraying, and sand slinging etc.
Monomer – It is a simple molecule capable of combining with a number of like or unlike molecules to form a polymer. It is a repeating structure unit within a polymer. It is a single molecule which can react with like or unlike molecules to form a polymer. It is the smallest repeating structure of a polymer (mer). For addition polymers, this represents the original unpolymerized compound.
Mono-ply belt – Mono-ply belt has single ply carcass. The one-ply carcass provides over 2000 kN/m tension. It has low elongation which allows short take-up strokes. Single layer carcass structure provides optimum troughing as well as provides high bendability hence, allowing small-diameter pulleys. Besides high bendability, the belt has impact-resistance. The thin carcass allows thick cover rubber layers, extending belt life span.
Monoscope – It is a raster scan video device which generates a single fixed image for test or identification purposes.
Monotectic – It is an isothermal reversible reaction in a binary system, in which a liquid on cooling decomposes into a second liquid of a different composition and a solid. It differs from a eutectic in that only one of the two products of the reaction is below its freezing range.
Monotonic loading – It is a testing procedure in which the load on the sample progressively increases or decreases, but does not oscillate in value.
Monotron hardness test – It is an obsolete method of determining indentation hardness by measuring the load needed to force a spherical penetrator into a metal to a specified depth.
Monotropism – It is the ability of a solid to exist in two or more forms (crystal structures), but in which one form is the stable modification at all temperatures and pressures. Ferrite and martensite are a monotropic pair below the temperature at which austenite begins to form, e.g., in steels. Its alternate spelling is monotrophism.
Monte Carlo simulation – It is a method of generating information for a simulation when events occur in a random way. The Monte Carlo method uses unrestricted random sampling in a computer simulation in which the results are run off repeatedly to develop statistically reliable answers.
Monte Carlo techniques – It consists of calculation of the trajectory of incident electrons within a given matrix and the pathway of the X-rays generated during interaction.
Monticellite – They are gray silicate minerals of the olivine group with compositions CaMgSiO4 and CaFeSiO4, respectively. Most monticellites have the pure magnesium end-member composition but rare ferroan monticellites and magnesio-kirschsteinite are found with between 30 mol. %and 75 mol. % of the iron end member.
Months of inventory – It is the ratio of the end-of-period inventory to average monthly level of sales for the period.
Moonbeam – It is a device attached to the end of a lead brace which allows a pile to be driven with a side batter.
Moore’s law – It is the observation that the number of transistors possible in an integrated circuit doubles approximately every two years.
Morphological matrix – In a formalized process for developing design concepts, it is a list of all functions needed by the design, including all of the conceivable ways of accomplishing each function.
Morphology – It is the characteristic shape, form, or surface texture or contours of the crystals, grains, or particles of (or in) a material, normally on a microscopic scale. It is the overall form of a polymer structure, i.e., crystallinity, branching, molecular weight, and so on.
Morse code – It is a method of transmitting text by long and short impulses and varying delays between them.
Mortars – Mortars are normally neither classified under refractory brick nor monolithic refractories. These are finely ground refractory materials, which become plastic when mixed with water. These are used to bond the brickwork into solid unit, to provide cushion between the slightly irregular surfaces of the brick, to fill up spaces created by a deformed shell, and to make a wall gas-tight to prevent penetration of slag into the joints. Mortars must have good water retention properties and must not sediment. In this way, premature penetration of water in the refractory bricks after laying, causing the mortar to dry out, can be avoided. Refractory mortars can be with ceramic bonding (bonding starting at 800 deg C), chemical bonding or hydraulic bonding (bonding starting at 20 deg C). The composition and characteristics of the mortar materials, grain size and consistency are the important properties of the mortars.
Mosaic crystal – It is an imperfect single crystal composed of regions which are slightly disoriented relative to each other.
Mosaic structure – In crystals, it is a sub-structure in which adjoining regions have only slightly different orientations.
MOSFET – It is metal oxide semi-conductor field effect transistor, a class of transistor using a single type of charge carrier and with a very thin insulating layer between current channel and control gate. If a person counts those built into integrated circuits, nearly all transistors are MOSFETs.
Mossbauer effect – It is the process in which gamma-radiation is emitted or absorbed by nuclei in solid matter without imparting re-coil energy to the nucleus and without Doppler broadening of the gamma-ray energy.
Mossbauer spectroscopy – It is an analytical technique which measures recoilless absorption of gamma-rays which have been emitted from a radioactive source as a function of the relative velocity between the absorber and the source.
Mossbauer spectrum – It is a plot of the relative absorption of gamma-rays against the relative velocity between an absorber and a source of gamma-rays.
Motion control – It is that part of automation which deals with accurately controlling the movements of machines.
Motion conversion actuators – These actuators are generally used to adapt a common translational motion from the actuator’s output to a rotary valve. The rod which moves axially from the translational motion actuator is connected to a disk and the connection is pivoted. The disk itself is also pivoted about its centre. This system of pivots allows the translational motion to be converted into the rotation of the disk, which opens or close the rotary valve. The main advantage of this set-up is that an inexpensive translational motion actuator can be used with rotary valves. The key draw-back is that the applications in which this can be used is very limited. Specifically, this set-up is useless in the common case where the rotary motion needed is greater than 90-degree.
Motor – It a device which uses petrol, gas, and electricity etc. to produce movement and makes a machine work. It is a prime mover.
Motor control centre (MCC) – It is an assembly to control some or all electric motors in a central location. It consists of multiple enclosed sections having a common power bus and with each section containing a combination starter, which in turn consists of motor starter, fuses or circuit breaker, and power disconnect. A motor control centre can also include push buttons, indicator lights, variable-frequency drives, programmable logic controllers, and metering equipment. It can be combined with the electrical service entrance for the building.
Motor controller – It is the electrical apparatus which regulates and protects an electric motor, which can be as simple as an on-off switch or a servo system for precision machine tools.
Motor drive – It is the system in which the motor is located and makes it spin. It is called the drive, and is also referred to as the electric drive or motor drive. In general, it is the device which controls the motor. Drives designed for electric motors are also called electric drives.
Motor-generator (MG) set – It is a set of machines which consists of one or more motors mechanically coupled to one or more generators. In motor generator set, the generator delivers direct current of appropriate amperage and voltage.
Motor soft starter – It is a device which reduces the inrush current when an electric motor is first connected to the power supply.
Mottled cast iron – It is the iron which consists of a mixture of variable proportions of gray cast iron and white cast iron. Such a material has a mottled fracture appearance.
Mottling, pressure – It is non-uniform surface appearance resulting from uneven pressure distribution between adjacent layers of the product.
Mould – It is the part or parts making up the confining form in which a powder is pressed or a sintered compact is repressed or coined. The term is frequently used to mean mould assembly. In case of composites, it is the cavity or matrix into or on which the plastic composition is placed and from which it takes form. It is also to shape plastic parts or finished articles by heat and pressure. It is the assembly of all the parts which function collectively in the moulding process.
Mould cavity – It is the space in a mould which is filled with liquid metal to form the casting upon solidification. The channel through which liquid metal enters the mould cavity (sprue, runner, gates) and reservoirs for liquid metal (risers) are not considered part of the mould cavity proper.
Mould coating – It is the coating to prevent surface defects on permanent mould castings and die castings. It is also the coating on sand molds to prevent metal penetration and to improve metal finish. It is also called mould facing or mould dressing.
Mould, continuous casting machine – Moulds play an important role in the process of continuous casting of liquid steel. They are the heart of the continuous casting process. In the process of continuous casting, liquid steel is poured from the tundish into the casting mould through the submerged entry nozzle (SEN) immersed in the liquid steel. The moulds are water cooled. Solidification of liquid begins in the mould by indirect cooling. The cooling process in the mould is known as primary cooling process. The mould is basically an open-ended box structure, containing a water-cooled inner lining fabricated from a high purity copper alloy. Small quantities of alloying elements are added to increase the strength. Mould water transfers heat from the solidifying shell. The working surface of the copper face is frequently plated with chromium or nickel to provide a harder working surface, and to avoid copper pickup on the surface of the cast strand, which can facilitate surface cracks on the cast steel. The depth of the mould can range from 0.5 metre to 2 metre depending on the casting speed and section size.
Moulded edge – It is an edge which is not physically altered after moulding for use in final form, and particularly one which does not have fibre ends along its length.
Moulded interconnect device (MID) – It is an injection-moulded thermo-plastic part with integrated electronic circuit traces. The use of high temperature thermo-plastics and their structured metallization opens a new dimension of circuit carrier design to the electronics industry This technology combines plastic substrate / housing with circuitry into a single part by selective metallization.
Moulded net – It is the description of a moulded part which needs no additional processing to meet dimensional requirements.
Mould-electro-magnetic stirrer (M-EMS) – It is located in the mould, as the name suggest. It carries out the in-mould stirring (sometimes termed as primary electro-magnetic stirrer). A rotary type mould-electro-magnetic stirrer is normally the first choice when selecting billet / bloom stirring equipment. The rotating magnetic field produced gives a circular motion in the liquid steel. The central equiaxed zone is enlarged since the rotational flow promotes the fracturing of the tips of the columnar dendrites, which then serve as nuclei for equiaxed crystal formations in the central zone. Further, the rotational flow flushes the solidification front, hence preventing inclusions and gas bubbles from being entrapped. Still further, the centrifugal force developed results in the lighter phases (i.e. inclusions and gas bubbles moving towards the centre of the strand away from the solidification front. Linear mould-electro-magnetic stirrer is used for larger rectangular strand sections. Two stirrers are then placed horizontally along the cast product wide sides, and the benefits are similar to those obtained with rotary stirring. mould-electro-magnetic stirrer has been traditionally built into the mould in an internal design, where the coil was removed from the caster with the mould. For each mould exchange, electric cables and possibly water hoses were to be connected / disconnected to the coil. New casting machines have external design in which the coil is built around the mould and remains in the casting machine during mould exchange.
Mould, foundry – It is the form, made of sand, metal, or refractory material, which contains the cavity into which molten metal is poured to produce a casting of desired shape. It is also a die.
Moulding – It is the forming of a polymer or composite into a solid mass of prescribed shape and size by the application of pressure and heat for given times. It is sometimes used to denote the finished part.
Moulding cycle – It is the period of time needed for the complete sequence of operations on a moulding press to produce one set of mouldings. It is also the operations which is necessary to produce a set of mouldings without reference to the total time taken.
Moulding machine – It is a machine for making sand moulds by mechanically compacting sand around a pattern.
Moulding powder or compound – It consists of plastic material in varying stages of pellets or granulation, and consisting of resin, filler, pigments, reinforcements, plasticizers, and other ingredients, ready for use in the moulding operation.
Moulding press – It is a press used to form powder metallurgy compacts.
Moulding pressure – It is the pressure which is applied to the ram of an injection machine, compression press, or transfer press to force the softened plastic to fill the mould cavities completely.
Moulding sands – It is the foundry sands containing more than 5 % natural clay, normally between 8 % and 20 %.
Mould jacket – It consists of wood or metal form which is slipped over a sand mould for support during pouring of a casting.
Mould oscillation – Mould oscillation is necessary to minimize friction and sticking of the solidifying shell, avoidance of shell tearing, and liquid steel breakouts. Breakouts can cause major damage to equipment and a large machine downtime is needed because of clean up and repairs. Friction between the shell and mould is reduced through the use of mould lubricants such as oils or powdered fluxes. Oscillation is achieved either hydraulically or through motor driven cams or levers which support and reciprocate (or oscillate) the mould. Mould oscillating cycles vary in frequency, stroke, and pattern. However, a common approach is to employ what is called ‘negative strip’, a stroke pattern in which the downward stroke of the cycle enables the mould to move down faster than the section withdrawal speed. This enables compressive stresses to develop in the shell which increase its strength by sealing surface fissures and porosity.
Mould powders – Continuous casting mould powders are used primarily to facilitate the passage of liquid steel through the mould of the continuous casting machine. It is also known by several other names such as mould powder, casting powder, mould flux, mould flux slag, or mould flux powder. Mould powder plays an important role in the continuous casting of liquid steel and is one of the most influential and critical factors in the stability of the casting process and for the smooth casting of the liquid steel. The mould powder improves the performance of the casting process and reduces the surface defects. The main functions of the mould powder are (i) to protect liquid steel against oxidation, (ii) to provide lubrication for the solidifying steel, (iii) to control, optimize, and insulate the heat transfer from the liquid steel to the mould and the ambient in horizontal and vertical directions, (iv) to absorb the inclusions from the liquid steel to produce cleaner cast steel product, and (v) to provide chemical protection to the liquid steel from oxidation and other undesired reactions. The high basicity of the mould powder increases its capability to assimilate non-metallic inclusions.
Mould-release agent – It is a lubricant, liquid, or powder (frequently silicone oils and waxes) used to prevent sticking of moulded articles in the cavity.
Mould seam – It is a vertical groove formed at the point of the mould halves. It can also be referred to as a parting line.
Mould shift – It is a casting defect which results when the parts of the mould do not match at the parting line.
Mould shrinkage – It is the immediate shrinkage which a moulded part undergoes when it is removed from a mould and cooled to room temperature. It is also the difference in dimensions, expressed in millimeter per millimeter, between a moulding and the mould cavity in which it has been moulded (at normal-temperature measurement). It is the incremental difference between the dimensions of the moulding and the mould from which it was made, expressed as a percentage of the mould dimensions.
Mould surface – It is the side of a laminate which faces the mould (tool) during cure in an autoclave or hydroclave.
Mould wash – It is an aqueous or alcoholic emulsion or suspension of different materials which is used to coat the surface of a casting mould cavity.
Mounting – It is a means by which a sample for metallographic examination can be held during preparation of a section surface. The sample can be embedded in plastic or secured mechanically in clamps.
Mounting artifact – It is a false structure introduced during the mounting stages of a surface-preparation sequence.
Mounting resin – It consists of thermo-setting or thermo-plastic resins which is used to mount metallographic samples.
Mouse, computer – It is a hand-held pointing device which detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of the pointer (called a cursor) on a display, which allows a smooth control of the graphical user interface of a computer.
Movement factor – It mainly deals with the movement of men and materials. A good layout is to ensure short moves and always tends towards completion of product. It also includes inter-departmental movements and material handling equipment. This includes the flow pattern reduction of unnecessary handling, space for movement, and analysis of handling methods.
Moving average (MA) processes – These are stationary time series which are characterized by a linear relationship between observations and past innovations. The order of the process ‘q’ defines the number of past innovations on which the current observation depends.
Moving bed bioreactor (MBBR) – Moving bed bioreactor process is a fixed film process in which the micro-organisms grow on plastic media. The media are made from high density polyethylene or polypropylene with a diameter of 13 millimeters to 25 millimeters and hence have a large surface area which helps the biomass to grow inside the surface and are in constant motion due to the compressed air which is blown from under the tank. The process has been applied in a variety of industrial wastewater treatment applications in aerobic and anaerobic modes with or without denitrification depending on the mode of mixing.
Moving range (MR) – It is the difference between the two consecutive individual values used as ‘range’ when number of items in a group is one.
MRI – It is magnetic resonance imaging. It a technique for examining the interiors of using sensitive measurements of the magnetic fields of atomic nuclei.
M-section – It consists of light weight beams which are mainly used in the construction of pre-engineered housing. These beams are produced in lighter weights, normally 10 kilograms per metre to 15 kilograms per metre.
M-shell – It is the third layer of electrons surrounding the nucleus of an atom, having electrons characterized by the principal quantum number 3.
‘Ms’ temperature – For any alloy system, it is the temperature at which martensite starts to form on cooling.
MTBF – It is ‘Mean Time between Failures’.
MTTF – It is ‘Mean Time to Failure’.
MTTR – It is ‘Mean Time to Restore (or Repair)’.
Muck – It is the ore or rock which has been broken by blasting.
Muck sample – It is a representative piece of ore which is taken from a muck pile and then assayed to determine the grade of the pile.
Mud cracks – These are microscale fractographic artifacts created when a liquid dries on the fracture surface. These cracks are frequently associated with (i) incomplete removal of a cleaning agent from a fracture surface prior to examination in the scanning electron microscope, or (ii) dried solutions created from stress-corrosion cracking conditions.
Mud gun – It is equipment installed near taphole in the cast house for pushing taphole mass under pressure in the taphole for the purpose of closing it. Mud gun performs one of the most important and critical operations of the tap hole. Closing a blast furnace tap hole under any condition is a key safety requirement.
Mud gun filling machine – These machines are used for the automatic filling of the mud gun.
Muffle furnace – It is a furnace in which the subject material is isolated from the fuel and all of the products of combustion, including gases and flying ash. After the development of high-temperature heating elements, new muffle furnaces quickly moved to electric designs. Today, a muffle furnace is often a front-loading box-type oven or kiln for high-temperature applications such as fusing glass, creating enamel coatings, ceramics and soldering and brazing articles. They are also used in testing laboratories to determine what proportion of a sample is non-combustible and non-volatile (i.e., ash).
Muller-Lyer illusion – It is an optical illusion consisting of three stylized arrows. When viewers are asked to place a mark on the figure at the midpoint, they tend to place it more towards the ‘tail’ end. Muller-Lyer illusion shows the difference between perception and reality. In case of visual inspection, the difference of perception between two inspectors depends upon training and experience and the mental and physical state of the observers at the time the observation is made. Perception can be affected by fatigue and health. Fatigue reduces the efficiency and visual ability of the observer. These problems lead to inaccurate interpretation of physical data. An ideal inspection is the one in which all of the factors namely training, experience, lighting, and environmental conditions are optimized.
Mullen test – It consists of measurement of bursting strength of foil in kilograms force per square centimeter. Testing machine applies increasing pressure to 645 square millimeters of the sample until it ruptures.
Mulling – It is the mixing and kneading of foundry moulding sand with moisture and clay to develop suitable properties for moulding.
Mullite – It is a rare silicate mineral formed during contact metamorphism of clay minerals. It can form two stoichiometric forms: 3Al2O3.2SiO2 or 2Al2O3.SiO2. Unusually, mullite has no charge-balancing cations present. As a result, there are three different aluminium sites namely two distorted tetrahedral and one octahedral. Mullite is present in the form of needles in porcelain. It is produced during different melting and firing processes, and is used as a refractory material, because of its high melting point of 1,840 deg C. Mullite morphology is important for its application. There are two common morphologies for mullite. One is a platelet shape with low aspect ratio and the second is a needle shape with high aspect ratio. If the needle shape mullite can form in a ceramic body during sintering, it has an effect on both the mechanical and physical properties by increasing the mechanical strength and thermal shock resistance. The most important condition relates to ceramic chemical composition. If the silica and alumina ratio with low basic materials such as sodium and calcium is adjusted, the needle shape mullite forms at around 1,400 deg C and the needles interlocks. This mechanical interlocking contributes to the high mechanical strength of porcelain.
Mullite refractories – Mullite refractories are manufactured from fused and sintered mullite grains and also with mullite forming natural minerals like sillimanite and andalusite.
Mullite refractory castable – It is mainly composed of mullite, whose components are Al2O3 and SiO2. The melting point of mullite is 1,910 deg C so that it has good refractoriness. This product presents the characteristics of low thermal expansion, good wear resistance, and good thermal resistance.
Multiaxial fatigue – It is a general term which can be used to describe loading and / or loading plus geometry conditions resulting in complex states of stresses and strains, either locally or globally. More specifically, multiaxial loading results in a state of stress and / or strain, which manifests as two or more components in the stress or strain tensor.
Multi-axial stresses – It is a stress state in which two or three principal stresses are not zero.
Multibody system – It is the study of the dynamic behaviour of inter-connected rigid or flexible bodies, each of which can undergo large translational and rotational displacements.
Multi-circuit winding – In filament winding, a winding which needs more than one circuit before the band repeats by laying adjacent to the first band.
Multi-channel analyzer (MCA) – It is an instrument which splits an input signal into a number of channels with respect to a particular parameter of the input.
Multi-chip module (MCM) – It is generically an electronic assembly (such as a package with a number of conductor terminals or ‘pins’) where multiple integrated circuits (ICs or ‘chips’), semi-conductor dies and / or other discrete components are integrated, normally onto a unifying substrate, so that in use it can be treated as if it is a larger integrated circuit. Other terms for multi-chip module packaging include heterogeneous integration or hybrid integrated circuit. The advantage of using multi-chip module packaging is that it allows a manufacturer to use multiple components for modularity and / or to improve yields over a conventional monolithic integrated circuit approach.
Multi-collinearity – It is the situation in a regression model in which two are more predictors are highly correlated with each other, leading to poor-quality coefficient estimates. Multi-collinearity is a term used to describe when two variables are correlated with each other. In statistical models, multi-collinearity causes problems with the efficiency of parameter estimates. It also raises some philosophical issues, since it becomes difficult to determine which variables (both, either, or none), are causal and which are the result of illusory correlation.
Multics – It is an influential early time-sharing computer operating system, first released in 1969.
Multi-disciplinary design optimization (MDO) – It is a field of engineering which uses optimization methods for solving the design problems incorporating a number of disciplines. Multi-disciplinary design optimization allows designers to incorporate all relevant disciplines simultaneously. The optimum of the simultaneous problem is superior to the design found by optimizing each discipline sequentially, since it can exploit the interactions between the disciplines. However, including all disciplines simultaneously significantly increases the complexity of the problem.
Multi-filament yarn – It consists of a large number (500 to 2000) of fine, continuous filaments (frequently 5 to 100 individual filaments), normally with some twist in the yarn to facilitate handling.
Multi-fuel burner – It is a burner by means of which more than one fuel can be burned.
Multi-grade oil – It is an oil having relatively little change in viscosity over a specified temperature range.
Multi hearth furnaces – These furnaces are a variation of the rotary hearth furnace with several levels of round stationary hearths with rotating rabble arms which gradually plow granular or small lump materials radially across the hearths, causing them to eventually drop through ports to the next level.
Multi-hole die – It is an extrusion die, with more than one hole, allowing multiple extrusions to be made simultaneously from one billet.
Multi-layer coating – It is a coating on a metal or non-metal which consists of two or more components, one of which is frequently particulate in form. Example is a cermet composite coating on a cemented carbide cutting tool.
Multi-meter – It is a test instrument that can measure current, voltage, or resistance (though not concurrently).
Multinomial logistic regression – It is a logistic regression model for a study end point with more than two values.
Multiple – It is a piece of stock for forging which is cut from bar or billet lengths to provide the exact quantity of material for a single work-piece.
Multiple-comparison procedure – It is a statistical procedure for comparing group means which avoids capitalization on chance.
Multiple-die pressing – it is the simultaneous compaction of powder into several identical parts with a press tool consisting of a number of components.
Multiple etching – It is the sequential etching of a micro-section, with specific reagents attacking distinct micro-constituents.
Multiple hearth furnaces – Multiple hearth furnaces used to be in a dominant position as a roasting furnace for sulphide ores (mainly pyrites in sulphuric acid production). It has now been almost completely replaced by fluidized-bed roasting equipment since the 1960s. A multiple hearth furnace consists of an internally lined steel cylinder with a number of horizontally mounted, lined platforms called hearths. The circular hearths are thinner near the centre, which has an opening for a vertical shaft. An adjustable-speed drive with overload protection turns the shaft at 0.2 revolutions per minute to 5 revolutions per minute. From 1 to 4 rabble arms per hearth are latched to the shaft in a gastight manner. These arms bear oblique stirring teeth to move the solids over the hearth. On one hearth, the motion is from centre to edge, on the next from edge to centre depending on the inclination of the stirring teeth. The openings in the hearths, through which the charge travels from the top of the furnace to the bottom, hence alternate from central to peripheral.
Multiple imputation – It is a means of filling in missing data which involves using the inter-relationships among variables in one’s analysis, along with random error, to estimate the missing values. This process is repeated to create multiple copies of one’s data; then one’s statistical analysis of the data is repeated with each copy of the dataset and the results are combined into one final set of results.
Multiple-layer alloy plating – It is a technology for engineering desirable properties into thin surface layers through the use of carefully controlled deposit micro-structures. As implied by the name, multiple-layer alloy electro-deposition involves the formation of an inhomogeneous alloy consisting of lamellae of different composition. In case of a binary alloy composed of species A and B, each lamella of species A (or species B) in the film has a nearly uniform thickness tA (or tB). The modulation wave-length (t = tA + tB) characterizes the imposed compositional micro-structure and typically takes a value anywhere from angstroms to micrometers in thickness. Multiple-layer thin films with spatially periodic compositional microstructures of the type in case of a binary alloy are sometimes referred to as composition-modulated alloys (CMAs) or as superlattice alloys.
Multiple linear regression – It is a linear regression involving two or more independent variables. Simple linear regression, which is merely used to illustrate the basic properties of regression models, contains one explanatory variable and is rarely if ever used in practice.
Multiple-pass weld – It is a weld made by depositing filler metal with two or more successive passes.
Multiple-ply belt – Multiple-ply belt is normally made up of two or more plies, or layers, of woven cotton, rayon, or a combination of these fabrics, bonded together by an elastomer compound. Belt strength and load support characteristics vary according to the number of plies and the fabric used. The multiple-ply conveyor belt was the most widely used belt through the mid-1960s, but today it has been replaced by reduced-ply belt.
Multiple punch press – It is a mechanical or hydraulic press which actuates several punches individually and independently of each other.
Multiple scattering event – It is a collision process which can be described as a sequence of binary scattering events that may or may not be elastic.
Multiple-slide press – It is a press with individual slides, built into the main slide or connected to individual eccentrics on the main shaft, which can be adjusted to vary the length of stroke and the timing.
Multiple spot welding – It is the spot welding in which several spots are made during one complete cycle of the welding machine.
Multiplier phototube – It is a device in which incident electro-magnetic radiation creates electrons by the photo-electric effect. These electrons are accelerated by a series of electrodes called dynodes, with secondary emission adding electrons to the stream at each dynode.
Multiplying factor – It means the number by which a data unit is multiplied to get the data in another unit. It is normally used for the conversion of units.
Multi-port burner – It is a burner having a number of nozzles from which fuel and air are discharged.
Multi-port nozzle, plasma arc welding and cutting – It is a constricting nozzle containing two or more orifices located in a configuration to achieve a degree of control over the arc shape.
Multi-roll mills – These rolling mills consist of six, seven, twelve or twenty horizontally mounted rolls. In all these mills there are only two rolls which are work rolls while all the other rolls are back-up rolls. Normally work rolls are driven and back-up rolls are friction driven. The multi-roll mills are used for rolling of very thin sheets, strips and foils.
Multisim – It is a brand of computer software for electronic circuit simulation.
Multi stand pipe mill (MPM) – It is the continuous mandrel rolling process which has arrangement in tandem several rolling passes in a series of rolling stands to form a rolling line. This mill type elongates the hollow shell pierced in the piercing mill over a floating mandrel bar acting as an internal tool to produce the finished pipe. In recent times, rolling practice in mills of this type employs controlled instead of freely floating mandrel bars. The advantage of this process variant lies in fact that substantially shorter and fewer mandrel bars are required. The multi stand pipe mill (MPM) is part of an efficient seamless pipe hot rolling process from the hot pierced shell. The mill is normally composed of 8 stands of two grooved rolls inclined by 90-degree from one stand to another. The material is mounted on a cooled and lubricated mandrel and pushed to the first stand where rolling begins. The mandrel runs along the multi stand pipe mill with constant speed. The tube is then cut, calibrated, treated and controlled before delivery.
Multivariate (or multivariable) analysis – It is an analysis in which one examines the simultaneous effect of two or more explanatory variables on a study end point.
Multivariate normal distribution – It is a multi-dimensional version of the normal distribution which characterizes a collection of variables. If a set of variables has a multivariate normal distribution, then the variables are all inter-correlated and each individual variable is normally distributed.
Mushy zone – It is the zone in blast furnace where soft structure of the ferrous burden is formed at temperatures of around 1,100 deg C.
Music wire – It is the most widely used of all spring materials for small springs since this wire is the toughest. It has the highest tensile strength and can withstand higher stresses under repeated loading conditions than any other spring material. It is available in diameters from 0.12 millimeters to 3 millimeters. It has a usable temperature range from 0 deg C to 120 deg C. Music wire contracts under heat and can be plated.
Mutually exclusive events – In probability theory, two events are said to be mutually exclusive if and only if they are represented by disjoint subsets of the sample space, namely, by subsets which have no elements or events in common. By definition the probability of mutually exclusive events A and B occurring is zero.
m-value – It is the increase in stress needed to cause a certain increase in plastic strain rate at a given level of plastic strain and a given temperature.
Mylar – It is a trade name for a polyester film which is used as a release sheet in adhesive and composite bonding. It is also used as food packaging.
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