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Glossary of technical terms for the use of metallurgical engineers  Terms starting with alphabet ‘E’

• satyendra
• October 3, 2024
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Glossary of technical terms for the use of metallurgical engineers 

Terms starting with alphabet ‘E’

Earing – It is the wavy symmetrical projections formed during cupping, deep drawing, or spinning. It is the formation of ears or scalloped edges around the top of a drawn shell, resulting from the directional differences in the plastic-working properties of rolled metal, with, across, or at angles to the direction of rolling. It can also be caused by improperly adjusted tooling.

Ears – It is the wavy symmetrical projections formed in the course of deep drawing or spinning as a result of directional properties or anisotropy in sheet. Ears occur in groups of four or eight with the peaks of the projections located at 45-degree and / or at 0-degree and 90-degree to the rolling direction. Degree of earing is the difference between average height at the peaks and average height at the valleys, divided by average height at the valleys, multiplied by 100 and expressed in percent.

Eccentric – It is the offset portion of the drive-shaft which governs the stroke or distance the cross-head moves on a mechanical or manual shear.

Eccentric bottom tapping – It takes place since the taphole is placed in the furnace bottom and closer to a side of the furnace. It permits controlled interruption of the tapping process by tilting the electric arc furnace in order to retain slag or liquid steel in the hearth. It leads to slag-free tapping, and shorter tap-to-tap times. It also reduces refractory and electrode consumption, and improves ladle life.

Eccentric gear – It is a main press-drive gear with an eccentric(s) as an integral part. The unit rotates about a common shaft, with the eccentric transmitting the rotary motion of the gear into the vertical motion of the slide through a connection.

Eccentricity – It is the deviation from a common centre as, e.g., the inner and outer walls of a round tube. It is the difference between the mean wall thickness and minimum or maximum wall thickness at any one cross section. The permissible degree of eccentricity can be expressed by a plus and minus wall-thickness tolerance. In journal bearings, it is the radial displacement of the journal centre from the centre of the bearing liner.

Eccentricity ratio – In a bearing, it is the ratio of the eccentricity to the radial clearance.

Eccentric press – It is a mechanical press in which an eccentric, instead of a crankshaft, is used to move the slide.

Economy of scale – It is the variation of cost with production volume. Normally, unit cost decreases with increasing volume.

Economy of scope – It is the concept that value is created more by the ability to create products with very many functions or variations from a common theme than by reducing the unit cost from increased volume of production.

Eddy current – It is a loop of electric current induced within conductors by a changing magnetic field in the conductor as per the Faraday’s law of induction or by the relative motion of a conductor in a magnetic field. Eddy currents flow in closed loops within conductors, in planes perpendicular to the magnetic field. They can be induced within nearby stationary conductors by a time-varying magnetic field created by an alternating current electro-magnet or transformer. The magnitude of the current in a given loop is proportional to the strength of the magnetic field, the area of the loop, and the rate of change of flux, and inversely proportional to the resistivity of the material. When graphed, these circular currents within a piece of metal look vaguely like eddies or whirlpools in a liquid.

Eddy current inspection – It is based on the principles of electro-magnetic induction and is used to identify or differentiate among a wide variety of physical, structural, and metallurgical conditions in electrically conductive ferro-magnetic and non-ferro-magnetic metals and metal parts. Eddy current inspection can be used to (i) measure or identify such conditions and properties as electrical conductivity, magnetic permeability, grain size, heat treatment condition, hardness, and physical dimensions, (ii) detect seams, laps, cracks, voids, and inclusions, (iii) sort dissimilar metals and detect differences in their composition, microstructure, and other properties, and (iv) measure the thickness of a non-conductive coating.

Eddy-current testing – It is an electro-magnetic non-destructive testing method in which eddy-current flow is induced in the test object. Changes in flow caused by variations in the object are reflected into a nearby coil or coils where they are detected and measured by suitable instrumentation. Eddy currents are influenced by the nature of the material such as voids, cracks, changes in grain size, as well as physical distance between coil and material. These currents form impedance on a second coil which is used to as a sensor. In practice a probe is placed on the surface of the part to be inspected, and electronic equipment monitors the eddy current in the work piece through the same probe. The sensing circuit is a part of the sending coil. The main applications of the eddy current technique are for the detection of surface or sub-surface flaws. The technique is sensitive to the material conductivity, permeability and dimensions of the product.

Edge, band – It is a sharp colour demarcation in the appearance of the metal because of a difference in the work roll coating.

Edge, belled – It is excessive buildup of material on edge(s) during a rewinding operation. Typical causes include excessive edge burr, turned edge, and dog bone-shaped cross-sectional profiles.

Edge, broken (cracked) – It is the edge(s) containing crack, split, and / or tear caused by the inability to deform without fracturing.

Edge, build-up – It is excessive buildup of material on edge(s) during a rewinding operation. Typical causes include excessive edge burr, turned edge, and dog bone-shaped cross-sectional profiles.

Edge, damaged – It is the edge of a coil which has been bent, torn, or scraped by an object.

Edge detection – It is an image processing technique which is used to identify boundaries of objects

Edge dislocation – It corresponds to the row of mismatched atoms along the edge formed by an extra, partial plane of atoms within the body of a crystal.

Edge distance – It is the distance from the edge of a bearing sample to the centre of the hole in the direction of applied force.

Edge distance ratio – It is the ratio of the edge distance to the pin diameter in a bearing test. It is also the distance from the centre of the bearing hole to the edge of the sample in the direction of the principal stress, divided by the diameter of the hole.

Edge, dropped – It is a continuous, downward edge deflection.

Edge flange joint – It is a flange weld with two members flanged at the location of welding.

Edge joint – It is a joint between the edges of two or more parallel or nearly parallel members. It is also a joint made by bonding the edge faces of two adherends.

Edge, liquated – It is the surface condition remaining after portions of a side of an as-cast rolling ingot deforms enough during hot rolling to become top and / or bottom surface(s) of the rolled product at an edge.

Edger – It is the portion of a die impression which distributes metal during forging into areas where it is most needed in order to facilitate filling the cavities of subsequent impressions to be used in the forging sequence.

edge, rippled – It consists of undulation (wavy region) along the edge(s) of the metal.

Edge stability – It is an indicator of strength in a green compact which can be determined by tumbling in a drum.

Edge strain – It consists of transverse strain lines or Luders lines ranging from 25 millimeters to 300 millimeters from the edges of cold rolled steel sheet or strip. Luder lines are elongated surface markings or depressions in sheet metal, frequently visible with the unaided eye, caused by discontinuous (inhomogeneous) yielding.

Edge strength – It is the resistance of the sharp edges of a compact against abrasion. It can be determined by tumbling in a drum.

Edge-trailing technique – It is a unidirectional motion perpendicular to and toward one edge of the sample during abrasion or polishing. It is used to improve edge retention.

Edge, wavy – It is the undulation (wavy region) along the edge(s) of the metal.

Edge weld – It is a weld in an edge joint.

Edge weld size – It is the weld metal thickness measured at the weld root.

Edging – In sheet metal forming, it consists of reducing the flange radius by retracting the forming punch a small amount after the stroke but before release of the pressure. In rolling, it is the working of metal in which the axis of the roll is parallel to the thickness dimension. It is also called edge rolling. It is also the forging operation of working a bar between contoured dies while turning it 90-degree between blows to produce a varying rectangular cross section. In a forging, it is the removing flash which is directed upward between dies, normally accomplished by using a lathe.

Edging impression – It is the portion of a die impression which distributes metal during forging into areas where it is most needed in order to facilitate filling the cavities of subsequent impressions to be used in the forging sequence.

Edging mill – It is equipped with caliber rolls and has the function of adjusting the flange widths of products. In the universal mill, variations of flange-thickness and web- thickness can be made easily by adjusting the roll gap in the edging mill. The edging mill is normally a two-high, single groove mill stand.

Effective area – In an actuator, it is the part of the diaphragm or piston area which produces a stem force. The effective area of a diaphragm can change as it is stroked. It is normally a maximum at the start and a minimum at the end of the travel range. Moulded diaphragms have less change in effective area than flat sheet diaphragms. Hence, molded diaphragms are desired.

Effective crack size – It is the physical crack size augmented for the effects of crack tip plastic deformation. Sometimes the effective crack size is calculated from a measured value of a physical crack size plus a calculated value of a plastic zone adjustment. A preferred method for calculation of effective crack size compares compliance from the secant of a load-deflection trace with the elastic compliance from a calibration for the type of sample.

Effective draw – It is the maximum limits of forming depth which can be achieved with a multiple-action press. It is sometimes called maximum draw or maximum depth of draw.

Effective leakage area – It is the orifice flow area which results in the same calculated flow for a given pressure drop as is measured for the seal in question. This concept is useful when comparing the leakage

performance of seals of different sizes and designs, and of seals operating under different conditions.

Effective radiation dose – it is the quantity got by multiplying the equivalent radiation dose to different tissues and organs by a weighting factor appropriate to each and summing the products. Its unit is Sievert, symbol Sv. It is frequently abbreviated to dose.

Effective stress – It is a calculated parameter which is used in a mathematical expression that predicts the onset of an event (typically yield and fatigue failure) when a critical value of the effective stress is obtained. The most common effective stress is the von Mises stress.

Effective throat – It is the minimum distance minus any convexity between the weld root and the face of a fillet weld.

Effective yield strength – It is an assumed value of uniaxial yield strength which represents the influence of plastic yielding on fracture test parameters.

Effect size – It is a measure of the strength of a relationship between two variables. Effect size statistics are used to assess comparisons between correlations, percentages, mean differences, probabilities, and so on.

Efficiency – It refers to the effectiveness with which a particular quantity of inputs is deployed to generate an output. When a process is technologically efficient, it produces a specific quantity of output using the least quantity of inputs.

Efficiency (statistical) – A statistical estimator or estimate is said to be efficient if it has small variance. In majority of the cases a statistical estimate is preferred if it is more efficient than alternative estimates. It can be shown that the Cramer-Rao bound represents the best possible efficiency (lowest variance) for an unbiased estimator. That is, if an unbiased estimator is shown to be equivalent to the Cramer-Rao bound, then there are no other unbiased estimators which are more efficient. It is possible in some cases to find a more efficient estimate of a population parameter which is biased.

E-glass – It is a family of glasses with a calcium alumino-boro-silicate composition and a maximum alkali content of 2 %. It contains a general-purpose fibre which is most frequently used in reinforced plastics, and is suitable for electrical laminates because of its high resistivity. It is also called electric glass.

Ejection – It is the removal of the compact after completion of the pressing, whereby the compact is pushed through the die cavity by one of the punches. It is also called knock-out.

Ejector – It is a device mounted in such a way that it removes or assists in removing a formed part from a die.

Ejector half – It is the movable half of a die-casting die containing the ejector pins.

Ejector pin – It is a pin (rod) which pushes the solidified die casting out of the die.

Ejector punch – It is a punch used for ejecting compacts.

Ejector rod – It is a rod used to push out a formed piece.

Elastic calibration device – It is a device for use in verifying the load readings of a testing machine consisting of an elastic member(s) to which loads can be applied, combined with a mechanism or device for indicating the magnitude (or a quantity proportional to the magnitude) of deformation under load.

Elastic compliance – It is a condition under which two bodies in contact, which are subjected to a force, undergo small elastic displacement without slip.

Elastic constants – These are the factors of proportionality which relate elastic displacement of a material to applied forces. Examples are bulk modulus of elasticity, modulus of elasticity, Poisson’s ratio, and shear modulus.

Elastic deformation – It is a change in dimensions directly proportional to and in phase with an increase or decrease in applied force.

Elastic electron scatter – It is the scatter of electrons by an object without loss of energy. It is normally an interaction between electrons and atoms.

Elastic energy – It is the quantity of energy needed to deform a material within its elastic range of behaviour, neglecting small heat losses because of the internal friction. The energy absorbed by a sample per unit volume of material contained within the gauge length being tested. It is determined by measuring the area under the stress-strain curve up to a specified elastic strain

Elastic hysteresis – It is a misnomer for an anelastic strain which lags a change in applied stress, hence creating energy loss during cyclic loading. It is more properly termed mechanical hysteresis.

Elasticity – It is the property of a material by virtue of which deformation caused by stress disappears upon removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after release of stress.

Elastic limit – It is the maximum stress which a material is capable of sustaining without any permanent strain (deformation) remaining upon complete release of the stress. A material is said to have passed its

elastic limit when the load is sufficient to initiate plastic, or non-recoverable, deformation.

Elastic modulus – It is same as modulus of elasticity. 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.

Elastic ratio – It is the yield point divided by tensile strength.

Elastic recovery – It is the quantity the dimension of a stressed elastic material returns to its original (unstressed) dimension on release of an applied load. In hardness testing, the shortening of the original dimensions of the indentation upon release of the applied load.

Elastic resilience – It is the quantity of energy absorbed in stressing a material up to the elastic limit, or it is the quantity of energy which can be recovered when stress is released from the elastic limit.

Elastic scattering – It is the collisions between particles that are completely described by conservation of energy and momentum.

Elastic strain – It is a change in dimensions directly proportional to and in phase with an increase or decrease in applied force.

Elastic strain energy – It is the energy expended by the action of external forces in deforming a body elastically. Essentially all the work performed during elastic deformation is stored as elastic energy, and this energy is recovered upon release of the applied force.

Elasto-hydro-dynamic lubrication – It is a condition of lubrication in which the friction and film thickness between two bodies in relative motion are determined by the elastic properties of the bodies, in combination with the viscous properties of the lubricant at the prevailing pressure, temperature, and rate of shear.

Elastomer – It is a natural or synthetic polymer, which at room temperature can be stretched repeatedly to at least twice its original length, and which after removal of the tensile load immediately and forcibly returns to approximately its original length.

Elastomer compatibility (sealing materials) – One important requirement for hydraulic fluids is that they are to be compatible with sealing materials and hydraulic hoses. The optimum in order for the hydraulic system to remain sealed is a moderate swelling (2 %). One of the most common materials in hoses (internal) and gaskets is nitrile rubber (NBR). Several other materials are used in hydraulic systems, which include fluoro-rubber (FPM with the trade name Viton), polyester urethane (AU) and polyether urethane (EU). Materials which are not suitable include natural rubber, polychloroprene (neoprene) and isobutylene isoprene.

Elastomeric coatings – These are fluid-applied roofing membranes with elastic properties that allow it to expand and contract with the substrate. Elongation is important because roofs expand and contract and this allows the roof coating to move with the substrate.

Elastomeric couplings – In general, these couplings obtain their flexibility from stretching or compressing a resilient material (rubber, plastic, etc.). Some sliding or rolling can take place, but it is normally minimal.

Elastomeric flexible coupling – These couplings typically utilize a plastic or rubber element that allows for the temperature growth or axial movement. The elastomeric element is sufficiently resistant to fatigue failure to provide an acceptable life compared to the cost of the coupling. Majority of the elastomeric flexible couplings do not use lubrication, and are loaded in shear.

Elastomeric tooling – It is a tooling system that uses the thermal expansion of rubber materials to form composite parts during cure. It uses rubber details to generate needed moulding pressure or to serve as a pressure intensifier during composite-part curing cycles. The rubber is made from castable room-temperature vulcanized (RTV) rubber compounds or calendered silicone rubber sheets (reinforced and unreinforced) in ‘B’ stage form (fully compounded but uncured).

Elbow – It is a pipe fitting which is installed between two lengths of pipe or tube allowing a change of direction, usually 90-degree or 45-degree. The ends can be machined for butt welding, threaded (normally female), or socketed, etc. When the two ends differ in size, it is called a reducing or reducer elbow. Most elbows are available in short radius or long radius of types. It is also a part of tuyere stock of a blast furnace. At the elbow, hot air blast takes 90-degree turn. Elbows have peep sight for watching inside the furnace.

Electret – It is a dielectric material which permanently retains an impressed electric field. It is the dual to a magnet.

Electric actuators – These actuators typically use standard motors, powered by either alternating current induction, direct current, or capacitor-start split-phase induction. The motor is connected to a gear or thread which creates thrust to move the valve. As a fail-safe, some motors are equipped with a lock in last position on its gear. This means that the gear cannot move from forces outside of the electric motor. This helps prevent overshoot on the motor as well as helps create better positioning for the gear.

Electrical cable – It is a flexible conducting wire to carry electrical power or signals, normally covered with an insulating material.

Electrical codes – These are a set of regulations for the use of electricity. They can vary from local to international in scope.

Electrical conductivity – It is the capacity or a measure of a substance’s ability to conduct an electric current. This capacity is expressed as a percentage of the International Annealed Copper Standard (IACS), which has a resistivity of 1/58 ohm-mm2/m (ohm square millimeter/metre) at 20 deg C and an arbitrarily designated conductivity of unity.

Electrical conductor – It is an object which carries an electric current, with little loss.

Electrical contact – It is a separable part of an electric device which carries current when touching another contact.

Electrical contact materials – These materials make and break electrical circuits. Contacts are made of either elemental metals, composites, or alloys which are made by the melt-cast method or produced by powder metallurgy processes. Powder metallurgy facilitates combinations of metals which ordinarily cannot be achieved by alloying. A majority of contact applications in the electrical industry utilize silver-type contacts, which include the pure metal, alloys, and powder metal combinations. Silver, which has the highest electrical and thermal conductivity of all metals, is also used as a plated, brazed, or mechanically bonded overlay on other contact materials, notably, copper and copper-base materials. Other types of contacts used include the platinum group metals, tungsten, molybdenum, copper, copper alloys, and mercury. Aluminum is normally a poor contact material since it oxidizes readily, but is used in some contact applications because of its good electrical and mechanical properties and its availability and cost.

Electrical control panels – These panels are enclosures fabricated out of steel sheet metal. They provide and control electric power to equipment and appliances. Provision for indicating electrical parameters like voltage, current, frequency, and power factor etc. are required to be available on the face of the panel. Regulation of the power supply is also possible with the help of auto transformer switches and circuit breaker.  These panels are designed and used to control mechanical equipment. Each one is designed for a specific equipment arrangement and includes devices which allow an operator to control specified equipment. Electrical panel components control every piece of equipment in several industries.

Electrical control panel descriptions – These descriptions are the terms and attributes which are used to describe the panels. An example of how to describe important control panel attributes is (i) safety ratings such as third-party safety certification, and SCCR, (ii) enclosure ratings such as NEMA (National Electrical Manufacturers Association) rating, (iii) material of construction such as 304 grade stainless steel, (iv) mounting such as wall mount or floor mount, (v) door mechanism such as lockable handle with three point door latch, (vi) main power both incoming power e.g., 440 V three-phase through a main circuit breaker, and outgoing power, (vii) control Power such as 110 V AC or 120 V AC and 24 V DC, (viii) door mounted operator devices, (viii) sequence of operation, and (ix) remote control interface.

Electrical control panel design – Designing of the industrial control panels can be a complex process, because of the need to meet all applicable regulatory standards and safety requirements. Developing the design matrix (DM) needs identification of user requirements. For the control panel of the automated modular construction machine, the user requirements include (i) to provide a 110 V AC or 120 V AC / 24 V DC control panel, (ii) to conform to standards, and (iii) to conform to best practices. All other requirements, such as maintainability, safety, and prevailing guidelines, which are included in these user requirements, comprise the high-level functional requirements (FRs). These requirements can be combined into one main requirement, which is to build a 110 V AC or 120 V AC / 24 V DC control panel.

Electrical discharge grinding – It consists of grinding by spark discharges between a negative electrode grinding wheel and a positive work-piece separated by a small gap containing a dielectric fluid such as petroleum oil.

Electrical discharge machining (EDM) – It is the metal removed by a rapid spark discharge between different polarity electrodes, one on the work-piece and the other the tool separated by a gap distance of 0.013 millimeters to 0.9 millimeters. The gap is filled with dielectric fluid and metal particles which are melted, in part vaporized, and expelled from the gap.

Electrical discharge wire cutting – It is a special form of electrical discharge machining wherein the electrode is a continuous moving conductive wire. It is also referred to as traveling wire electrical discharge machining.

Electrical disintegration – It is the metal removal by an electrical spark acting in air. It is not subject to precise control, the most common application being the removal of broken tools such as taps and drills.

Electrical dissipation factor – it is the ratio of the power loss in a dielectric material to the total power transmitted through it. Hence, there is the imperfection of the dielectric. It is equal to the tangent of the loss angle.

Electrical element – In circuit theory, it is a node at which some electrical property is concentrated (e.g., resistance, etc.).

Electrical enclosure – It is a cabinet or box which protects electrical or electronic equipment and prevents electrical shock. Enclosures are normally made from rigid plastics or such metals as steel, stainless steel, or aluminum.

Electrical engineering – It is that branch of engineering which deals with the application of electricity to practical issues.

Electrical equipment – It is a device for the generation, transmission, or utilization of electric power.

Electrical grid – It is a geographically distributed system to connect source and users of electric power.

Electrical impedance – It is that property of a circuit which hat resists the passage of electric current, normally in the context of alternating current.

Electrical insulation – It is a material which resists electrical current flow.

Electrical insulation paper – It is a grade of paper which is used for insulation of transformers, electrical machines, capacitors, and some cables.

Electrical isolation – It is the separation of two conductive materials from electrical contact. Galvanized steel is sometimes electrically isolated in order to prevent rapid consumption of the zinc coating.

Electrical load – it is a consumer of electrical energy, turning it into light, heat, mechanical power, data, or chemical changes.

Electrical machine – It is a general term for machines using electro-magnetic forces, such as electric motors, electric generators, and others. They are electromechanical energy converters, e.g., an electric motor converts electricity to mechanical power while an electric generator converts mechanical power to electricity. The moving parts in a machine can be rotating (rotating machines) or linear (linear machines).

Electrical measurements – It is that branch of metrology which is concerned with electrical quantities.

Electrical network – It is a network of electrical components and conductors.

Electrical permittivity – It is the material property that directly relates the voltage and geometry of the system to the electrical field energy. Magnetic permeability is the magnetic field energy counterpart.

Electrical pitting – It is the formation of surface cavities by removal of metal as a result of an electrical discharge across an interface.

Electrical polarity – It is the identification of electrical terminals where current is flowing in the same direction relative to the device.

Electrical resistance alloys – These alloys include those types used in instruments and control equipment, heating elements, and devices which convert heat generated to mechanical energy. They are classified as resistance alloys, heating alloys, and thermostat metals. The primary requirements for resistance alloys are uniform resistivity, stable resistance (no time-dependent aging effects), reproducible temperature coefficient of resistance, and low thermoelectric potential against copper. Properties of secondary importance are coefficient of expansion, mechanical strength, ductility, corrosion resistance, and ability to be joined to other metals by soldering, brazing, or welding. The heating alloys are mainly used for heating elements where the main requirements are high melting point, high electrical resistivity, reproductible temperature coefficient of resistance, good oxidation resistance, absence of volatile components, and resistance of contamination. Other desirable properties are good high-temperature creep strength, high emissivity, low thermal expansion, and low modulus (both of which help minimize thermal fatigue), good resistance to thermal shock, and good strength and ductility at fabrication temperatures. Thermostat metal is a composite material (normally in the form of sheet or strip) which consists of two or more materials bonded together, of which one can be a non-metal. Since the materials bonded together to form the composite differ in thermal expansion, the curvature of the composite is altered by changes in temperature. This is the fundamental characteristics of a thermostat metal. Thermostat metal is hence a complete, self-contained transducing system capable of transforming heat directly into mechanical energy for control, indicating, or monitoring purposes.

Electrical resistivity – It is the electrical resistance offered by a material of unit length and unit cross-sectional area or unit weight to the flow of current. It is the reciprocal of the conductivity. The value of 1⁄58 ohm-mm2/m (ohm square millimeter/metre) at 20 deg C is the resistivity equivalent to the International Annealed Copper Standard (IACS) for 100 % conductivity. This means that a wire of 100% conductivity, 1 meter in length and 1 square millimeter in cross-sectional area has a resistance of 0.017241 ohms at 20 deg C.

Electrical safety – It is the needed process to avoid electrical incidents through correct use of electrical equipment.

Electrical set-point, electric arc furnace – It consists of transformer tap, reactor tap, and impedance set-points.

Electrical steel – It is a kind of special steel which is tailored to show certain specific magnetic properties such as small hysteresis area resulting in low energy dissipation per cycle, low power loss per cycle, low core loss, and high permeability. It is also called lamination steel, silicon steel, silicon-electrical steel, or transformer steel. The steel contains specific percentage of silicon in it which is responsible for its unique property. The exact formulation is tailored to produce specific magnetic properties. It is a speciality steel which is used in the cores of electromagnetic devices such as motors, generators, and transformers since it reduces power loss. Electrical steel has special physical properties which make it suitable for application in the production of electric equipments and appliances with rotating magnetic fields.  Electrical steel is normally produced in cold-rolled strips of less than 2-millimeter thickness. Types of electrical steel are either non oriented electrical steel or grain oriented electrical steel.

Electrical substation – It is a facility connecting a distribution network to a transmission network, normally with one or more transformers.

Electrical wiring – It is the installation of conductors, fixtures and protection devices for or an equipment.

Electric arc – it is the discharge of electric current through an open space between conductors. It can be produced intentionally as a source of intense light and heat, or can be a result of an electrical fault.

Electric arc furnace (EAF) – An electric arc furnace is a furnace which heats material by means of an electric arc, combined with the action of chemical power provided by the use of oxygen and fuel. In electric arc furnaces, the charged material is directly exposed to an electric arc, and current from the furnace electrodes passes through the charged material. Arc furnaces differ from induction furnaces, in which the charge is instead heated by eddy currents. Electric arc furnace can be either a direct current furnace or an alternating current furnace. Industrial arc furnaces range in size from small units of approximately one-ton capacity up to about 400-ton unit. The furnace is used for the melting and refining of steel products and are a well-known source of flicker. The most prevalent use of this furnace is in the recycling of scrap steel. However, electric arc furnaces are also used in the production of high-grade alloy steel, aluminum, copper, lead and other metals.

Electric arc furnace expert system – It is an integrated process control supervisor. It automatically recognizes deviations from the expected behaviour and re-tunes the melting program, acting on the electric power planning, on the chemical package, on the slag and steel metallurgy. Equipment constraints are integrated into the control. The expert system acts as a process supervisor which integrates basic automation and technological functions to enable the steel production in an effective and safe way, supporting each operation from the charging phase up to the tapping procedure.

Electric arc spraying – It is a thermal spraying process using an arc between two consumable electrodes of surfacing materials as a heat source and a compressed gas to atomize and propel the surfacing material to the substrate.

Electric bonding – It is a term for surfacing by thermal spraying which consists of a group of processes in which finely divided metallic or non-metallic surfacing materials are deposited in a molten or semi-molten condition on a substrate to form a spray deposit. The surfacing material can be in the form of powder, rod, or wire.

Electric brazing – It is a brazing process in which the heat needed is obtained from the resistance to electric current flow in a circuit of which the work-piece is a part. It is also a brazing process which uses an arc to provide the heat.

Electric charge – It is the physical property of matter which causes it to experience a force when placed in an electro-magnetic field.

Electric circuit – It is a closed path through which an electric current can flow.

Electric current – It is the motion of electric charges.

Electric current perturbation (ECP) – It is an electro-magnetic non-destructive evaluation method for detecting and characterizing defects in non-ferro-magnetic material. Laboratory evaluations have shown that this method can detect very small surface and subsurface cracks in both low-conductivity and high-conductivity metals (for example, titanium and aluminum alloys). Results from experiments and an analytical electric current perturbation model confirm that linear relationships exist between the electric current perturbation signal amplitude and the crack interfacial area and between the signal peak-to-peak separation and the crack length.

Electric dipole – It is the result of a distribution of bound charges, i.e., separated charges which are bound to their centres of equilibrium by an elastic force Equal numbers of positive and negative charges are to be present in an uncharged medium.

Electric dipole moment – It is a quantity characteristic of a distribution of bound charges equal to the vector sum over the charges of the product of the charge and the position vector of the charge.

Electric dipole transition – It is a transition of an atom, molecule, or nucleus from one energy state to another, which results from the interaction of electro-magnetic radiation with the dipole moment of the molecule, atom, or nucleus.

Electric drive – It is the system in which the electric motor is located and makes it spin. It is also referred to as the motor drive. In general, the device which controls the motor is called a drive. Electric drives are used to control the speed of motor. Electric drive can control both voltage and frequency input to the motor. If only voltage input to the motor is controlled by drive, then speed of motor is controlled. If both voltage and frequency inputs are controlled by drive then torque of motor is controlled. Drives can do more than control speed. The drive can also run the motor clockwise, counter clockwise or at a certain torque.

Electric field – It is a vector field which exerts a force on electric charges.

Electric field effect – It is a shift in the energy of spectral lines because of an electrical field which is either externally applied or is an internal field caused by the presence of neighboring ions or atoms in a gas, solid, or liquid. It is also known as the Stark effect.

Electric field gradient – It is the rate of change of electric field with respect to distance.

Electric furnace – It is used for industrial process heating. It uses electricity for heating in place of a fuel. It can use resistance or induction heating. It is a metal melting, holding, or heating furnace which produces heat from electricity. It can operate on the resistance or induction principle.

Electric generator – It is a machine which converts mechanical energy to electrical energy by moving conductors through magnetic fields.

Electric glass – It is a family of glasses with a calcium alumino-boro-silicate composition and a maximum alkali content of 2 %. It contains a general-purpose fibre which is most frequently used in reinforced plastics, and is suitable for electrical laminates because of its high resistivity. It is also called E glass.

Electric hazard – A dangerous condition such that contact or equipment failure can result in electric shock, arc flash burn, thermal burn, or blast.

Electric hoists – These are normally used in the production shops for the raising, lowering and transporting material throughout the shop and positioning components in process or assembly operations. Electric hoist is powered by electrically driven motor. It is easy to operate and offer more flexibility. It is frequently specified when the application calls for more frequent and faster lifting, such as on a production line. An electric hoist with a motorized trolley is ideal for repetitive lifts which are required to travel long distances. Electric hoists can be a chain hoist or a wire rope hoist.

Electricity – It is the set of physical phenomena associated with electric charges

Electricity meter – it is an instrument for the measurement of the electrical energy consumed at the user end.

Electric motor – It is an electro-mechanical energy conversion device which convert electrical energy to mechanical energy through the action of a magnetic field. It is a machine which produces mechanical energy from electrical energy.

Electric potential – It is a measure of the work required to move a unit electric charge in an electric field.

Electric power – It is the rate of transfer of electrical energy past a given point within a circuit. Its unit is the watt, the general unit of power, which is defined as one joule per second. Standard prefixes apply to watts are thousands, millions and billions of watts are called kilowatts, megawatts and gigawatts respectively. Electric power is normally produced by electric generators, but can also be supplied by sources such as electric batteries.

Electric power distribution – It is the final stage in the delivery of electricity. Electricity is carried from the transmission system to individual consumers.

Electric power transmission – It is a process by which the electric power is transported over long distances for eventual use by consumers. Electric power is transported over long distances at high voltages, which minimizes the loss of electricity. It is sent from generating power plants to the end consumer by transmission lines. Electricity by nature is difficult to store, hence the supply is to equal the demand at any given instant.

Electric resistance welded (ERW) pipes and tubes – These pipes and tubes are manufactured by rolling metal and then welding it longitudinally across its length. ERW pipes have a welded joint in their cross-section. It is manufactured from strip / coil and can be manufactured up to 600 mm outer diameter.

Electric shock – It is an injury caused to people by electric current.

Electric upsetting – It is a very different process compared to split die machine upsetting, but can be used to produce similar forgings. Normally, it is used to gather a large volume of metal at the end or along the length of a bar which is subsequently forged to a finished shape in another operation. Upset forming of the work-piece results when intense electric current is passed through the work-piece between contacts called the vise and anvil. The resistance to current flow heats the bar between the contacts to the plastic state. Force is applied to the cold ends of the bar pushing it through the vise at a controlled rate of speed. The heated portion grows into a bulb-shaped section. As the volume in the bulb-shaped section increases, its resistance, relative to the volume, decreases, hence slowing the heating in that portion. The smaller portion of the work-piece between contacts has more resistance and continues to heat and enlarge. The anvil retracts slowly when the bulb grows to the desired diameter allowing room for an elongated shape to develop. Large upset ratios can be achieved, exceeding 4 diameters, with superior grain flow characteristics when compared to other gathering methods. The upset part, using the same heat, can go directly to the forging operation. Normally, because of the high upset ratios possible, normally only one blow in the forging press or hammer is needed.

Electrification – It is applying electric power to a process which has been previously done by other means, or, development of an electric power system in a region which previously had none.

Electro-active polymers – These are polymers which significantly changes size or shape when exposed to an electric field.

Electro-chemical admittance – It is the inverse of electro-chemical impedance.

Electro-chemical cell – It is an electrochemical system consisting of an anode and a cathode in metallic contact and immersed in an electrolyte. The anode and cathode can be different metals or dissimilar areas on the same metal surface.

Electro-chemical corrosion – It is the corrosion which is accompanied by a flow of electrons between cathodic and anodic areas on metallic surfaces.

Electro-chemical discharge machining – It is the metal removal by a combination of the processes of electro-chemical machining (ECM) and electrical discharge machining (EDM). Majority of the metal removal occurs through anodic dissolution (i.e., ECM action). Oxide films which form as a result of electrolytic action through an electrolytic fluid are removed by intermittent spark discharges (i.e., EDM action). Hence, the combination of the two actions.

Electro-chemical engineering – It is that branch of engineering which deals with the application of electro-chemistry to practical issues.

Electro-chemical equivalent – It is the weight of an element or group of elements oxidized or reduced at 100 % efficiency by the passage of a unit quantity of electricity. It is normally expressed as grams per coulomb.

Electro-chemical (chemical) etching – It is the general expression for all developments of micro-structure through reduction and oxidation (redox reactions).

Electro-chemical grinding – It is a process whereby metal is removed by deplating. The work-piece is the anode, while the cathode is a conductive aluminum oxide-copper or metal-bonded diamond grinding wheel with abrasive particles. Majority of the metal is removed by deplating, around 0.05 % to 10 % is removed by abrasive cutting.

Electro-chemical impedance – It is the frequency-dependent complex-valued proportionality factor (delta E/ delta i) between the applied potential or current and the response signal. This factor is the total opposition (omega or omega·cm2) of an electro-chemical system to the passage of charge. The value is related to the corrosion rate under certain circumstances.

Electro-chemical machining (ECM) – It is the controlled metal removal by anodic dissolution. Direct current passes through flowing film of conductive solution which separates the work-piece from the electrode tool. The work-piece is the anode, and the tool is the cathode.

Electro-chemical polishing – It is an attack-polishing method in which the chemical action of the polishing fluid is improved or controlled by the application of an electric current between the sample and the polishing wheel.

Electro-chemical potential – It is the partial derivative of the total electro-chemical free energy of a constituent with respect to the number of moles of this constituent where all factors are kept constant. It is analogous to the chemical potential of a constituent except that it includes the electric as well as chemical contributions to the free energy. It is the potential of an electrode in an electrolyte relative to a reference electrode measured under open circuit conditions.

Electro-chemical reaction – It is a reaction caused by passage of an electric current through a medium that contains mobile ions (as in electrolysis); or, a spontaneous reaction made to cause current to flow in a conductor external to this medium (as in a galvanic cell). In either event, electrical connection is made to the external portion of the circuit through a pair of electrodes.

Electro-chemical series – It is the series of elements arranged as per their standard electrode potentials, with ‘noble’ metals such as gold being positive and ‘active’ metals such as zinc being negative. In corrosion studies, the analogous but more practical galvanic series of metals is normally used. The relative positions of a given metal are not necessarily the same in the two series.

Electro-corrosive wear – It is the wear of a solid surface which is accelerated by the presence of a corrosion-inducing electrical potential across the contact interface. This process is normally associated with wear in the presence of a liquid electrolyte in the interface. However, moisture from the air can also facilitate this type of wear when a galvanic wear couple exists and the contacting materials are sufficiently reactive.

Electrode – It is compressed graphite or carbon cylinder or rod used to conduct electric current in electric arc furnaces, arc lamps, and so forth. Anode and cathode are two types of electrodes.

Electrode, electro-chemistry – It consists of one of a pair of conductors introduced into an electrochemical cell, between which the ions in the intervening medium flow in opposite directions and on whose surfaces, reactions occur (when appropriate external connection is made). In direct current operation, one electrode or ‘pole’ is positively charged, the other negatively.

Electrode cable – It is the electrical conductor between the source of arc welding current and the electrode holder.

Electrode control system – It is the key control system for an electric arc furnace. It approaches towards an automated power control normally rely on evaluations of the arc current and voltage. It is a closed-loop electrode control system. The basic task is to control the position of the electrodes, more specific to maintain the electrical operating points.

Electrode deposition – It is the weight of weld-metal deposit obtained from a unit length of electrode.

Electrode extension – For gas metal arc welding, flux cored arc welding, and submerged arc welding, it is the length of unmelted electrode extending beyond the end of the contact tube.

Electrode force – It is the force between electrodes in a spot, seam, and projection weld.

Electrode holder – It is a device used for mechanically holding the electrode while conducting current to it.

Electrode indentation, resistance welding – It is the depression formed on the surface of work-pieces by electrodes.

Electrode lead – It is the electrical conductor between the source of arc welding current and the electrode holder.

Electrode polarization – It is the change of electrode potential with respect to a reference value. The change can be caused, for example, by the application of an external electrical current or by the addition of an oxidant or reductant.

Electro-deposition – It is (i) the deposition of a conductive material from a plating solution by the application of electric current, and (ii) The deposition of a substance on an electrode by passing electric current through an electrolyte. Electro-chemical plating, electro-forming, electro-refining, and electro-winning result from electro-deposition.

Electrode potential – It is the potential of an electrode in electrolysis as measured against a reference electrode. The electrode potential does not include any resistance losses in potential in either the solution or external circuit. It represents the reversible work to move a unit charge from the electrode surface through the solution to the reference electrode. It is also the difference in potential between an electrode and the immediately adjacent electrolyte referred to some standard electrode potential as zero. Different types of electrode potentials are dynamic, equilibrium, static, and standard.

Electrode quality steel – It is made of steel grade having low carbon steel (less than 0.1 %), low sulphur and phosphorus contents, and low percentage of silicon (less than 0.1 %). Excess silicon in welding wire results in heavy sputtering and gassing in weld pool. The electrode quality steel also has only small quantities of aluminum and copper levels. These elements are to be kept very low since they can cause undesirable brittleness in the weld metal. Earlier electrode quality steels were of rimming quality steel when the steelmaking used to follow the ingot casting route.

Electrode reaction – It is the interfacial reaction equivalent to a transfer of charge between electronic and ionic conductors.

Electrode, welding – In arc welding, it is a current-carrying rod which supports the arc between the rod and work-piece, or between two rods as in twin carbon-arc welding. It may or may not furnish filler metal. In resistance welding, it is a part of a resistance welding machine through which current and, in majority of the cases, pressure is applied directly to the work-piece. The electrode can be in the form of a rotating wheel, rotating roll, bar, cylinder, plate, clamp, chuck, or modification thereof. In arc and plasma spraying, it is the current-carrying components which support the arc.

Electro-dialysis, and electro-dialysis reversal processes – These are water softening processes which are driven by direct current in which ions (as opposed to water in pressure driven methods) flow through ion selective membranes to electrodes of opposite charge.

Electro-formed mould – It is a mould made by electro-plating metal on the reverse pattern of the cavity. Molten steel can then be sprayed on the back of the mould to increase its strength.

Electro-forming – It is the process by which articles or shapes can be exactly reproduced by electrode-position on a mandrel or form that is later removed, leaving a precise duplicate of the original. In certain applications, the mandrel is designed to remain as an integral part of the final electro-formed object. Electro-forms themselves can be used as parents or masters, normally with special passivating treatments so the secondary electro-form can be easily removed. The same or similar electro-deposition additives as those used for electro-plating are needed for electro-forming for controlling deposit stress, grain size, and other resultant mechanical properties in order to produce high-quality electro-forms.

Electro-galvanizing – It is the electro-plating of zinc upon iron or steel. Electro-galvanizing the sheet and wire in coil form produces a thin, uniform coating of pure zinc with excellent adherence. The coating is smooth, readily prepared for painting by phosphatizing, and free of the characteristics-spangles of hot dip zinc coatings. Electro-galvanizing can be used where a fine surface finish is needed. The appearance of the coating can be varied by additives and special treatments in the plating bath.

Electro-gas welding (EGW) – It is an arc welding process which produces coalescence of metals by heating them with an arc between a continuous filler metal electrode and the work-piece. Moulding shoes are used to confine the molten weld metal for vertical position welding. The electrodes can either be flux cored or solid. Shielding may or may not be obtained from an externally supplied gas or mixture.

Electro-gravimetry – it is the oldest electro-analytical technique. In it, the element of interest is to be deposited electrolytically onto an electrode and weighed. Unlike majority of the electro-chemical techniques, the reaction is to be frequently allowed to go to completion efficiently, prolonging analysis times. However, the technique is more accurate (0.1 %) than controlled potential coulometry (0.2 % to 5 %) or polarography (2 %). Use of efficient stirring lessens analysis time. Overall analysis time depends on the technique used.

Electro-kinetic potential – This potential which is sometimes called zeta potential, is a potential difference in the solution caused by residual, unbalanced charge distribution in the adjoining solution, producing a double layer. The electro-kinetic potential is different from the electrode potential in that it occurs exclusively in the solution phase, i.e., it represents the reversible work necessary to bring unit charge from infinity in the solution up to the interface in question but not through the interface.

Electroless deposition – It is an auto-catalytic process where the substrate develops a potential in a plating bath containing metallic ions, reducing agent, complexing agent, stabilizer and other components.

Electro-less nickel plating – It is used to deposit nickel without the use of an electric current. The coating is deposited by an auto-catalytic chemical reduction of nickel ions by hypo-phosphite, amino-borane, or boro-hydride compounds. Two other methods have been used commercially for plating nickel without electric current, including (I) immersion plating on steel from solutions of nickel chloride and boric acid at 70 deg C, and (ii) decomposition of nickel carbonyl vapour at 180 deg C. Immersion deposits, however, are poorly adherent and non-protective, while the decomposition of nickel carbonyl is expensive and hazardous. Hence, only electro-less nickel plating has gained wide acceptance.

Electro-less plating – It is a process in which metal ions in a dilute aqueous solution are plated out on a substrate by means of auto-catalytic chemical reduction. It is also the deposition of conductive material from an auto-catalytic plating solution without the application of electrical current.

Electrolysis – It is the chemical change resulting from the passage of an electric current through an electrolyte. It is also the separation of chemical components by the passage of current through an electrolyte. In electrolysis, an electric current is passed through a solution containing dissolved metals, causing the metals to be deposited onto a cathode.

Electrolyte – It is a chemical substance or mixture, normally liquid, containing ions which migrate in an electric field. It is also a chemical compound or mixture of compounds which when molten or in solution conducts an electric current.

Electrolytic brightening – It is a technique normally used to prepare metallographic samples, in which a high polish is produced making the sample the anode in an electrolytic cell, where preferential dissolution at high points smooths the surface.

Electrolytic cell – It is an assembly, consisting of a vessel, electrodes, and an electrolyte, in which electrolysis can be carried out. It is a unit apparatus in which electro-chemical reactions are produced by applying electrical energy, or which supplies electrical energy as a result of chemical reactions and which includes two or more electrodes and one or more electrolytes contained in a suitable vessel.

Electrolytic cleaning – It is a process of removing soil, scale, or corrosion products from a metal surface by subjecting it as an electrode to an electric current in an electrolytic bath.

Electrolytic corrosion – It is the corrosion by means of electro-chemical or mechanical action.

Electrolytic copper – It is the copper which has been refined by electro-deposition, including cathodes which are the direct product of the refining operation. Refinery shapes cast from melted cathodes, and, by extension, fabricators’ products made therefrom. Normally when this term is used alone, it refers to electrolytic tough pitch copper without elements other than oxygen being present in significant quantities.

Electrolytic deposition – It is the deposition of a conductive material from a plating solution by the application of electrical current. It is also the deposition of a substance on an electrode by passing electric current through an electrolyte. Electro-plating, electro-forming, electro-refining, and electro-winning result from electro-deposition.

Electrolytic etching – It consists of the development of micro-structure by selective dissolution of the polished surface under application of a direct current.

Electrolytic extraction – It is the removal of phases by using an electrolytic cell containing an electrolyte which preferentially dissolves the metal matrix.

Electrolytic grinding – It is a combination of grinding and machining wherein a metal-bonded abrasive wheel, normally diamond, is the cathode in physical contact with the anodic work-piece, the contact being made beneath the surface of a suitable electrolyte. The abrasive particles which produce grinding act as non-conducting spacers permitting simultaneous machining through electrolysis.

Electrolytic machining – It is the controlled removal of metal using an applied potential and a suitable electrolyte to produce the shapes and dimensions desired.

Electrolytic pickling – It is the pickling in which electric current is used, the work-piece being one of the electrodes.

Electrolytic polishing – It is an electrochemical polishing process in which the metal to be polished is made the anode in an electrolytic cell where preferential dissolution at high points in the surface topography produces a specularly reflective surface.

Electrolytic powder – It is the powder produced by electro-deposition or by pulverizing of an electrodeposit.

Electrolytic protection – The preferred term is cathodic protection which is the partial or complete protection of a metal from corrosion by making it a cathode, using either a galvanic or an impressed current.

Electrolytic refining – It is the process of purifying metal ingots which are suspended as anodes in an electrolytic bath, alternated with refined sheets of the same metal which act as starters or cathodes.

Electrolytic tough pitch – It is a term used for describing the method of raw copper preparation to ensure a good physical-grade and electrical-grade copper-finished product.

Electro-magnet – It is a magnet which generates a magnetic field from an electric current.

Electro-magnetic braking – Electro-magnetic braking of the liquid steel flow in the mould of a continuous casting machine improves the quality of the cast steel by reducing the penetration of non-metallic inclusions.

Electro-magnetic compatibility – It is the control of unwanted electro-magnetic interference.

Electro-magnetic field – It is the field produced by moving electric charges and magnetic fields.

Electro-magnetic focusing device – It is a device which effectively increases the angular aperture of the electron beam illuminating the object, rendering the focusing more critical.

Electro-magnetic forming – It is an assembly technique which is widely used to both join and shape metals and other materials with precision and rapidity, and without the heat effects and tool marks associated with other techniques. It is also known as magnetic pulse forming. The electro-magnetic forming process uses the direct application of a pressure created in an intense, transient magnetic field. Without mechanical contact, a metal work-piece is formed by the passage of a pulse of electric current through a forming coil. It is also known as magnetic pulse forming.

Electro-magnetic induction – It is the production of current in a circuit by the change of magnetic field intersecting the circuit.

Electro-magnetic lens – It is an electro-magnet designed to produce a suitably shaped magnetic field for the focusing and deflection of electrons or other charged particles in electron-optical instrumentation.

Electro-magnetic methods – They detect the electrical properties of the subsurface by inducing electro-magnetic energy within the subsurface and measuring the response of earth materials. Normally, electro-magnetic geophysical instruments output a time-varying electric current into its transmitter coil, or loop. As the current travels in the transmitter loop, it generates a magnetic field that has the same frequency and phase as the current. This induced field propagates lines of force that penetrate the earth.

Electro-magnetic radiation – It is the energy propagated by an electro-magnetic field. It consists of radio waves, light and other radiation which travels through space at the speed of light.

Electro-magnetic spectrum – It is the range of frequencies of electro-magnetic radiation. The electro-magnetic spectrum includes the several approximate wavelength regions as given in Tab 1.

 Electro-magnetic stirring (EMS) – It is the process by which a high level of stirring efficiency can be achieved through interaction between the magnetic field from the static induction coil and the electrically conducting metal bath. Electromagnetic stirring generates a fluid flow by the Lorenz force provided by a linear induction motor. EMS technology has been used in the continuous casting of steel for several years but the effect of the application and subsequent benefits of stirring the liquid core depends very much on section size, steel grade, and product application. It differs from the conventional mechanical and decompression types as it is a non-contact stirrer in which no part touches the liquid steel.

Electro-magnetic (EM) survey – It is a geophysical survey method which measures the electro-magnetic properties of the rocks.

Electro-magnetic techniques – These techniques are used for residual stress measurements. Residual stresses in materials can be non-destructively measured by a variety of methods, including x-ray diffraction, ultrasonic, and electro-magnetic techniques. With electro-magnetic techniques, one or more of the magnetic properties of a material (such as permeability, magnetostriction, hysteresis, coercive force, or magnetic domain wall motion during magnetization) are sensed and correlated to stress. These techniques rely on the change in magnetic properties of the material caused by stress, which is known as the magneto-elastic effect. These techniques, hence, apply only to ferro-magnetic materials, such as steel.

Electro-magnetism – It is the science of electric fields, magnetic fields, currents, charges, and forces. It is an interaction which occurs between particles with electric charge through electro-magnetic fields. The electro-magnetic force is one of the four fundamental forces of nature. It is the dominant force in the interactions of atoms and molecules. Electro-magnetism can be thought of as a combination of electrostatics and magnetism, which are distinct but closely intertwined phenomena.

Electro-mechanical – It is a system which has both an electrical component and a mechanical component, such as a motor or a relay.

Electro-mechanical mud gun – A mud gun is used to close the tap hole after tapping is complete. A quantity of the tap hole mass is pushed by the mud gun to fill the worn hole and to maintain a quantity of the tap hole mass (the mushroom) within the hearth. The mud gun is normally held in place on the tap hole until the tap hole mass cures and the tap hole is securely plugged. It has three separate electric drives for unit swing, barrel positioning, and ramming. Hence several separate motions are needed for accurate positioning of the mud gun at the tap hole. Tap hole mass injection pressure is in the range of only 5 MPa to 8 MPa. The electro-mechanical mud gun is latched to the furnace to keep it in place during plugging.

Electro-mechanical polishing – It is an attack-polishing method in which the chemical action of the polishing fluid is improved or controlled by the application of an electric current between the sample and the polishing wheel.

Electro- mechanical valves – These valves have electro magnets controlling whether the valve is open or closed. These valves can only be fully open or fully closed.

Electro-metallurgy – It that branch of metallurgical engineering which deals with the industrial recovery or processing of metals and alloys by electric or electrolytic methods.

Electrometric titration – It consists of a family of techniques in which the location of the endpoint of a titration involves the measurement of, or observation of changes in, some electrical quantity. Examples of such quantities include potential, current, conductance, frequency, and phase.

Electro-motive force – It is the force which determines the flow of electricity. It is a difference of electric potential. In electromagnetism and electronics, electromotive force is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical transducers provide an emf by converting other forms of energy into electrical energy.

Electro-motive force series (emf series) – It is a series of elements arranged according to their standard electrode potentials, with ‘noble’ metals such as gold being positive and ‘active’ metals such as zinc being negative. In corrosion studies, the analogous but more practical galvanic series of metals is normally used. The relative positions of a given metal are not necessarily the same in the two series.

Electron – It is a very small negatively charged particle which orbits the nucleus of an atom, and can also exist in a free state for short periods of time.

Electron bands – It is the energy states for the free electrons in a metal, as described by the use of the band theory (zone theory) of electron structure. It is also called Brillouin zones.

Electron beam – It is a stream of electrons in an electron-optical system.

Electron-beam curing – It is a system for curing paint films using the energy of an electron beam. The process lends itself to high-speed curing of paint on flat surfaces. Special paints are to be used and personal shielding is needed.

Electron beam cutting – It is a cutting process which uses the heat got from a concentrated beam composed mainly of high-velocity electrons, which impinge on the work-pieces to be cut, it may or may not use an externally supplied gas.

Electron beam gun – It is a device for producing and accelerating electrons. Typical components include the emitter (also called the filament or cathode), which is heated to produce electrons through thermionic emission, a cup (also called the grid or grid cup), and the anode.

Electron beam hardening treatment (EBHT) – It is a short surface hardening procedure for martensitically hardenable ferrous materials. Austenitizing occurs through the energy transferred by electron beams. Precise application of the energy with respect to workpiece location and elapsed time using a focused and deflectable electron beam makes it the process of choice, especially for the partial hardening of highly stressed surface regions in components. The austenitizing process advances from the surface toward the inner core regions of the component through heat conduction, hence allowing for a defined adjustment of the hardness penetration by selecting a suitable energy transfer duration. Typical hardening depths got by this process range from 0.1 millimeters to 1.5 millimeters. The rapid cooling of the austenite needed for martensite formation occurs through a self-quenching process which is dependent on the thermal conductivity and starts after the energy transfer has ceased. Depending on the material selected, the workpiece thickness required should be at least 5 times to 10 times the austenitizing depth.

Electron beam heat treating – It is a selective surface hardening process which rapidly heats a surface by direct bombardment with an accelerated stream of electrons.

Electron beam machining – It is removing material by melting and vaporizing the work-piece at the point of impingement of a focused high-velocity beam of electrons. The machining is done in high vacuum to eliminate scattering of the electrons due to interaction with gas molecules. The most important use of electron beam machining is for hole drilling.

Electron beam melting (EBM) – It is a 3-dimention manufacturing process in which a powdered metal is melted by a high-energy beam of electrons. An electron beam produces a stream of electrons that is guided by a magnetic field, melting layer upon layer of powdered metal to create an object matching the precise specifications defined by a computer aided design model. Production takes place in a vacuum chamber to guard against oxidation that can compromise highly reactive materials.

Electron-beam radiation – It is the radiation generated from high-energy electrons which is used in cross-linking coating systems.

Electron beam welding (EBW) – It is a welding process which produces coalescence of metals with the heat got from a concentrated beam composed primarily of high-velocity electrons impinging on the surfaces to be joined.

Electron diffraction – It is the phenomenon, or the technique of producing diffraction patterns through the incidence of electrons upon matter.

Electro-negativity – It is the relative tendency of an atom to attract electrons. Carbon, the basic building block of polymers, is neutral in this respect with a Pauling electro-negativity of 2.5. Metallic atoms on the left side of the periodic table have a propensity to lose electrons when forming covalent bonds, and their electro-negativities are less than 2.5. The atoms on the right side of the periodic table tend to gain electrons, and their electro-negativities tend to be higher than 2.5.

Electron energy loss spectroscopy (EELS) – It is a spectrographic technique in the electron microscope which analyzes the energy distribution of the electrons transmitted through the sample. The energy loss spectrum is characteristic of the chemical composition of the region being sampled.

Electron flow – It is a movement of electrons in an external circuit an anode and cathode in a corrosion cell. The current flow is arbitrarily considered to be in an opposite direction to the electron flow.

Electron gun – It is a device for producing and accelerating a beam of electrons.

Electronic amplifier – It is a device which increases the power of an electrical signal by electronic means.

Electronic circuit – It is a circuit using one or more electronic devices.

Electronic component – It is an active or passive element of an electronic circuit.

Electronic control unit – In some equipments, it is an embedded electronic system which controls certain aspects of equipment operation.

Electronic design automation – It is also referred to as electronic computer-aided design (ECAD). It is a category of software tools for designing electronic systems such as integrated circuits and printed circuit boards.

Electronic engineering – It is a branch of engineering which deals with the application of electronics to the practical issues.

Electronic filter – It is a filter which alters some frequency-related characteristic of a signal.

Electronic or electrical valves – In these valves, the movement of the ball or flap which controls the flow is controlled electronically through circuits or digitally. These types of valves have very precise control but can also be very expensive.

Electronics – It is the study of the flow of electrons through a vacuum, gases, or semi-conductors.

Electronic speed control – It is a device for regulating the speed of a motor.

Electron image – It is a representation of an object formed by a beam of electrons focused by an electron-optical system.

Electron lens – It is a device for focusing an electron beam to produce an image of an object.

Electron micrograph – It is a reproduction of an image formed by the action of an electron beam on a photographic emulsion.

Electron microscope – it is an electron-optical device that produces a magnified image of an object. Detail can be revealed by selective transmission, reflection, or emission of electrons by the object. It is a microscope which uses a beam of electrons as a source of illumination. They use electron optics which are analogous to the glass lenses of an optical light microscope to control the electron beam, for example focusing them to produce magnified images or electron diffraction patterns. As the wavelength of an electron can be up to 100,000 times smaller than that of visible light, electron microscopes have a much higher resolution of about 0.1 nanometer, which compares to around 200 nanometers for light microscopes.

Electron microscope column – It is the assembly of gun, lenses, sample, and viewing and plate chambers.

Electron microscopy -It is the study of materials by means of an electron microscope.

Electron microscopy impression – It is the reproduction of the surface contours of a sample formed in a plastic material after the application of pressure, heat, or both.

Electron multiplier phototube – It is a device in which incident electro-magnetic radiation creates electrons by the photoelectric effect. These electrons are accelerated by a series of electrodes called dynodes, with secondary emission adding electrons to the stream at each dynode. It is also known as multiplier phototube, photoelectric electron-multiplier tube, and photomultiplier tube.

Electron optical axis – It is the path of an electron through an electron-optical system, along which it suffers no deflection due to lens fields. This axis does not necessarily coincide with the mechanical axis of the system.

Electron optical system – It is a combination of parts capable of producing and controlling a beam of electrons to yield an image of an object.

Electron probe – It is a narrow beam of electrons which is used to scan or illuminate an object or screen.

Electron probe x-ray micro-analysis (EPMA) – It is a technique in analytical chemistry in which a finely focused beam of electrons is used to excite an x-ray spectrum characteristic of the elements in a small region of the sample.

Electron scattering – It is a change in the direction of propagation or kinetic energy of an electron as a result of a collision.

Electron spin resonance (ESR) – it is also known as electron paramagnetic resonance (EPR) and paramagnetic resonance. It is an instrumental technique which can provide a great deal of information on any material containing unpaired electrons. Such materials are ordinarily paramagnetic, although they can sometimes be ordered magnetic solids, such as ferro-magnets. If placed in a microwave-resonant cavity between the pole pieces of a strong electro-magnet, such a sample absorbs microwave energy at particular values of the magnetic field which are characteristic of the positions and the crystalline environments of the unpaired electrons. Plotting the microwave absorption intensity against the magnetic-field strength yields a line spectrum. The number, positions, intensities, and shapes of the component lines provide information used to identify and specify such components and properties of the sample as the degree of crystallinity, valence states of ions, local crystalline environments, defects and trace transition ions, radiation products, and free radicals.

Electron trajectory – It is the path of an electron.

Electron velocity – It is the rate of motion of an electron.

Electron wave-length It is the wave-length necessary to account for the deviation of electron rays in crystals by wave diffraction theory. It is numerically equal to the quotient of Planck’s constant divided by the electron momentum.

Electrophoresis – It is the transport of charged colloidal or macro-molecular materials in an electric field.

Electrophoretic paint (e-coat) – It is a paint which is applied by electrophoresis, in which colloidal charged particles are transported within an electric field.

Electrophorus – It is an instrument which is used to produce electrostatic charge through electrostatic induction.

Electro-plate – It is the application of a metallic coating on a surface by means of electrolytic action.

Electro-plating – It is the electrode-position of an adherent metallic coating on an object serving as a cathode for the purpose of securing a surface with properties or dimensions different from those of the substrate.

Electro-polishing – It is a technique normally used to prepare metallographic samples, in which a high polish is produced making the sample the anode in an electrolytic cell, where preferential dissolution at high points smooth the surface. It is also referred to as electrolytic polishing.

Electro-refining – It is using electric or electrolytic methods to convert impure metal to purer metal, or to produce an alloy from impure or partly purified raw materials.

Electro-slag remelting (ESR) – It is a consumable-electrode remelting process in which heat is generated by the passage of electric current through a conductive slag. The droplets of metal are refined by contact with the slag.

Electro-slag remelting (ESR) process – It is a consumable-electrode remelting process in which heat is generated by the passage of electric current through a conductive slag. The droplets of metal are refined by contact with the slag. This process is a continuous process. In this process, during the remelting of the consumable electrode, refining and solidification of the steel take place at the same time. Cast, rolled or forged steel ingots can be used as a consumable electrode. The process is based on an electrical current running through an electrode through the liquid slag and ingot. Because of the high electrical resistance of the slag, the slag heats up and melts. The complete remelting process is carried out in a water-cooled copper mould, which allows the remelted ingot to solidify quickly and very uniformly. It is a secondary steelmaking process which is used for remelting and refining of steels and special alloys normally used for critical applications in aircraft, thermal and nuclear power plants, and defense hardware, etc. The main purpose of the electroslag remelting process is to control the non-metallic inclusions in the steel, remove segregations and shrinkage, and produce more homogenous ingots. This process is normally essential for heavy steel ingots.

Electro-slag welding (ESW) – It is a welding process which produces coalescence of metals with molten slag that melts the filler metal and the surfaces of the work-pieces. The weld pool is shielded by this slag, which moves along the full cross section of the joint as welding progresses. The process is initiated by an arc that heats the slag. The arc is then extinguished by the conductive slag, which is kept molten by its

resistance to electric current passing through the electrode and the work-pieces.

Electro-tinning – It consists of electro-plating of tin on an object.

Electrostatic focusing device – It is a device which effectively increases the angular aperture of the electron beam illuminating the object, rendering the focusing more critical.

Electrostatic immersion lens – It is a lens system in which the object space is at a potential or in a medium of index of refraction different from that of the image space.

Electrostatic lens – It is a lens producing a potential field capable of deflecting electron rays to form an image of an object.

Electrostatic motor – It is a motor which relies on the forces generated by electric fields, instead of magnetic fields.

Electrostatic precipitator (ESP) – An electrostatic precipitator is a particulate collection device which removes particles from a flowing gas (such as exhaust gas) using the force of an induced electrostatic charge. Electrostatic precipitators are highly efficient filtration devices which minimally impede the flow of gases through the device, and can easily remove fine particulate matter from the exhaust gas stream. Electrostatic precipitator applies energy only to the particulate matter being collected and therefore is very efficient in its consumption of energy (in the form of electricity). It consists of (i) baffles for the distribution of the flow of exhaust gas, (ii) discharge and collection electrodes, (iii) a dust clean-out system, and (iv) collection hoppers. A high DC voltage is applied to the discharge electrodes to charge the particles, which then are attracted to oppositely charged collection electrodes on which they get trapped.

Electrostatics – It is the study of stationary electric charges and resulting forces.

Electrostatic spray – It is the process by which paint particles are electrically charged and attracted to a substrate bearing an opposite charge.

Electro-strictive effect – It is the reversible interaction, showed by some crystalline materials, between an elastic strain and an electric field. The direction of the strain is independent of the polarity of the field.

Electro-thermal furnaces – These are the furnace which uses electricity for the generation of heat.

Electro-tinning – It is electro-plating tin on an object.

Electro-typing – It is the production of printing plates by electro-forming.

Electro-winning – It is the recovery of a metal from an ore by means of electro-chemical processes.

Element – It is a chemical substance which cannot be broken down into other substances by chemical reactions. The basic particle which constitutes an element is the atom. Element is identified by the number of protons in its nucleus, known as the element’s atomic number. Element cannot be broken down into simpler substances. It retains its basic physical properties, regardless of the number of atoms in a sample.

Elemental analysis – Elemental analysis is a process where a sample of some material is analyzed for its elemental and sometimes isotopic composition. Elemental analysis can be qualitative, and it can be quantitative. It also consists of the determination of the percentage composition of the different elements present in an organic compound. It is one of the oldest quantitative techniques. It remains one of the first steps taken to investigate a new or unknown substance. The determination of the elemental composition of a sample normally enables the writing of an empirical formula for the substance under investigation, i.e., writing a formula expressing the relative number of the different atoms present. Some examples of empirical formulas are CH4 (methane, natural gas), HC2H3O2 (acetic acid), and C2H6O (ethyl alcohol).

Elliptical bearing – It is a two-lobed bearing. It is one type of non-circular journal bearing which has two main advantages over the conventional circular bearings namely lower temperature rise and lower vibrations.

Elliptical gears – A set of like elliptical gears can run at a constant center distance, but deliver an output speed that changes as they rotate. Elliptical gears come in two basic types (i) uni-lobe, which rotates about one of two fixed points on its long axis, and bi-lobe, which rotates about its centre. The speed-reduction ratio of these gears varies from 1/K to K during each cycle of rotation, where practical values of K range up to 3. As the gears rotate, the radii of the driving and driven gears change, so that speed first decreases for 1/4 revolution, then increases for 1/4 revolution, etc. These periods of increasing or decreasing speed occur four times per revolution. Elliptical gears are normally used in packaging and conveyor applications.

Elongated alpha – It is a fibrous structure brought about by unidirectional metalworking. It can be improved by the prior presence of blocky and / or grain-boundary alpha.

Elongated grain – It is a grain with one principal axis slightly longer than either of the other two.

Elongation – It is a term used in mechanical testing to describe the quantity of extension of a test piece when stressed. It is expressed in units of length or as strain (percent change in length). Quantitative value describing the length increase of the gauge length of a tensile-test bar because of the deformation up to and including the fracture process. It is to be noted that elongation (expressed as length or strain) is not an inherent material property but depends on the dimension of the sample tested as well as whether it is measured under load, such as with a laser extensometer, or after fracture, normally after manually remating the fracture surfaces in a fixture.

Elongation at break – It is the elongation recorded at the moment of rupture of the sample. It is frequently expressed as a percentage of the original length.

Elongation, percent – it is the extension of a uniform section of a sample expressed as a percentage of the original gauge length calculated by the formula percent elongation = [(Lx- Lo)/Lo)x100], where Lo is the original gauge length and Lx is the final gauge length.

Elutriation – It is a test for particle size in which the speed of a liquid or gas is used to suspend particles of a desired size, with larger sizes settling for removal and weighing, while smaller sizes are removed,

collected, and weighed at certain time intervals.

Embeddability – It is the ability of a bearing material to embed harmful foreign particles and reduce their tendency to cause scoring or abrasion.

Embedded abrasive – It consists of fragments of abrasive particles forced into the surface of a work-piece during grinding, abrasion, or polishing.

Embedded operating system – It is the common operating environment which supports embedded software. It can be a highly tailored version of a general-purpose operating system, or written solely for the purpose of embedded system operations.

Embedded software – It is a firmware component of a micro-processor-controlled system.

Embedded system – It is a specialized computer system which controls a device or system, with no or a minimal user interface. It is a combination of a computer processor, computer memory, and input / output peripheral devices, i.e., it has a dedicated function within a larger mechanical or electronic system.

Embodiment design – It is the stage after conceptual design in the engineering design process in which the features of a part and their arrangement and connectivity are determined. Qualitative reasoning based on fundamental principles is used to make decisions between alternatives. A sketch of the part and preliminary decisions on material selection and manufacturing methods are made in this stage.

Final dimensions and tolerances are not determined in this stage. It is also known as configuration design.

Embossing – It is a technique which is used to create depressions of a specific pattern in plastic film and sheeting. Such embossing in the form of surface patterns can be achieved on moulded parts by the treatment of the mould surface with photo-engraving or another process. It is also raising a design in relief against a surface.

Embossing die – It is a die used for producing embossed designs.

Embrittlement – It is the severe loss of ductility or toughness or both, of a material, normally a metal or alloy. Several forms of embrittlement can lead to brittle fracture. Several forms can occur during thermal

treatment or high-temperature service (thermally induced embrittlement). Some of these forms of embrittlement, which affect steels, include blue brittleness, 475 deg C embrittlement, quench-age embrittlement, sigma-phase embrittlement, strain-age embrittlement, temper embrittlement, tempered martensite embrittlement, and thermal embrittlement. In addition, steels and other metals and alloys can be embrittled by environmental conditions (environmentally assisted embrittlement). The forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid metal embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress-corrosion cracking.

Embrittlement, 475 deg C – It is the embrittlement of stainless steels upon extended exposure to temperatures between 400 deg C and 510 deg C. This type of embrittlement is caused by fine, chromium-rich precipitates which segregate at grain boundaries. Time at temperature directly influences the quantity of segregation. Grain-boundary segregation of the chromium-rich precipitates increases strength and hardness, decreases ductility and toughness, and changes corrosion resistance. This type of embrittlement can be reversed by heating above the precipitation range.

Emergency – It is a non-routine situation which necessitates prompt action, primarily to mitigate a hazard or adverse consequences for human life and health, property, and the environment.

Emergency core cooling system – It comprises a series of systems which are designed to safely shut down a nuclear reactor during accident conditions. Under normal conditions, heat is removed from a nuclear reactor by condensing steam after it passes through the turbine. In a boiling water reactor, condensed steam (water) is fed back into the reactor. In a pressurized water reactor, it is fed back through the heat.

Emergency plan – It is detailed procedures for responding to an emergency such as fire, explosion, chemical spill, or an uncontrolled release of gas or energy. Emergency plan is a description of the objectives, policy, and concept of operations for the response to an emergency and of the structure, authorities and responsibilities for a systematic, coordinated and effective response. Emergency plan minimizes the effects of a disaster.

Emergency plume gamma monitoring system – It is a site boundary system for monitoring any airbourne radioactivity released from a nuclear site.

Emergency preparedness – It is the state of being prepared for an emergency so as to minimize the damage. It is the capability to take actions which effectively mitigate the consequences of an emergency for human life and health, property, and the environment.

Emergency procedures – These are a set of instructions describing in detail the actions to be taken by emergency workers in an emergency.

Emergency reference level (ERL) – It consists of one of a dual set of doses likely to be averted by the introduction of counter-measures to protect the public from ionizing radiation after a nuclear or other serious accident.

Emergency shutdown valve – It is a valve or a system of valves which, when activated, initiate a shutdown of the plant, process, or platform they are tied to.

Emery – It is naturally occurring abrasive containing 57 % to 75 % aluminum oxide and a remainder of iron oxide and impurities.

Emission (of electro-magnetic radiation) – It is the creation of radiant energy in matter, resulting in a corresponding decrease in the energy of the emitting system.

Emission lines – These are spectral lines resulting from emission of electro-magnetic radiation by atoms, ions, or molecules during changes from excited states to states of lower energy.

Emissions – These are substances released into the air and are measured by their concentrations, or parts per million, in the atmosphere. Technically, an emission is anything which is being released out into the open. But more frequently it refers to gases being released into the air, like greenhouse gasses or emissions from power plants and factories. The main greenhouse gases are water vapour, carbon di-oxide, methane, nitrous oxide, hydro-fluoro-carbons, per-fluoro-carbons and sulphur hexa-fluoride.

Emission spectrometer – It is an instrument which measures percent concentrations of elements in samples of metals and other materials. When the sample is vapourized by an electric spark or arc, the characteristic wave-lengths of light emitted by each element are measured with a diffraction grating and an array of photo-detectors or photographic plates.

Emission spectroscopy – It is the branch of spectroscopy treating the theory, interpretation, and application of spectra originating in the emission of electro-magnetic radiation by atoms, ions, radicals, and molecules.

Emission spectrum – It is an electro-magnetic spectrum which is produced when radiation from an emitting source, excited by any of different forms of energy, is dispersed.

Emissivity – It is the ratio of the quantity of energy or of energetic particles radiated from a unit area of a surface to the quantity radiated from a unit area of an ideal emitter under the same conditions.

Employee – Employee is a person who is on the payroll of the organization. The employee has an employee number which identifies the person as an employee of the organization and who is directly supervised by a representative of the organization. Temporary or agency workers hired directly by the organization are to be considered as employees if the organization has primary responsibility for supervising their activities.

Employer – Employer is a person or organization with recognized responsibilities, commitments and duties towards a worker in the employment of the person or organization by virtue of a mutually agreed relationship.

Emulsification – It is the property of lubricating oil to get mixed with water easily. Emulsions can be oil in water emulsion or water in oil emulsion.

Emulsifying agent – It is a substance which increases the stability of an emulsion.

Emulsion – It is a stable dispersion of one liquid in another, normally by means of an emulsifying agent which has affinity for both the continuous and discontinuous phases. The emulsifying agent, discontinuous phase, and continuous phase can together produce another phase which serves as an enveloping (encapsulating) protective phase around the discontinuous phase.

Emulsion calibration curve – It is the plot of a function of the relative transmittance of the photographic emulsion against a function of the exposure. The calibration curve is used in spectrographic analysis to calculate the relative intensity of a radiant source from the density of a photographically recorded image.

Emulsion cleaner – It is a cleaner consisting of organic solvents dispersed in an aqueous medium with the aid of an emulsifying agent. Majority of the emulsion cleaners include emulsifying agents, and some are aided by surfactants. Emulsion cleaners are normally used in situations where alkaline or acid cleaners are not applicable.

Emulsion cleaning – It is an industrial cleaning process which uses an organic solvent as the main active agent. The solvent is normally a hydro-carbon of distilled petroleum dispersed in water. The emulsion, which alone is potentially volatile, is suspended in a non-volatile aqueous vehicle.

Emulsion inversion – An emulsion is said to invert when, e.g., a water-in-oil emulsion changes to an oil-in-water emulsion.

Enamel – It is essentially a glass with a low softening temperature ranging from 510 deg C to 530 deg C. It is a glass obtained by fusion at high temperature between 1,000 deg C and 1,300 deg C. Enamels normally consist of an acidic refractory material such as quartz, feldspar, clays and mica. In order to confer on enamelled parts its properties of durability, silica glass has to be modified, as it cannot be used in its original state. Its melting point is too high, its coefficient of thermal expansion is too low compared to that of steel and its adhesion to steel is zero. Hence, various additives need to be added in order to obtain enamel. Depending on the ultimate function of the enamel, various additives which can be used are pigments, opacifiers, clays or other materials to serve as deflocculants and floatation agents, which help suspend the enamel particles in an aqueous solution.

Enamel coating – It is a substantially vitreous or glassy inorganic coating bonded to the steel substrate by thermal fusion. This coating is applied for the protection of steel products from surrounding environments. This coating provides not only an aesthetic exterior but also provides outstanding engineering properties, such as mechanical strength of the enameled surface, multiplicity and stability of colour, corrosion resistance, resistance to wear and abrasion, chemical and heat resistance, resistance to thermal shock and fire, hygiene and ease of cleaning etc.

Enameling process – The enameling process involves applying and firing one or more layers of enamel on one or both sides of a suitable steel substrate. Successful enameling is characterized by (i) good adhesion of enamel to the steel, and (ii) a good surface appearance after firing of the enamel. The carbon content of the steel can hinder the process of achieving these two properties. Carbon content of steel is important for ensuring the adhesion of enamel. However, if the carbon content is too high then it can adversely affect the surface appearance of the enamel because of the release of gaseous carbon di-oxide and carbon mono-oxide produced during firing.

Enameled wire – It is a wire insulated with a thin flexible layer of enamel, used for electrical windings.

Enameling iron – It is a low-carbon, cold-rolled sheet steel, produced specifically for use as a base metal for porcelain enamel.

Enantiotropy – It is the relation of crystal forms of the same substance in which one form is stable above a certain temperature and the other form is stable below that temperature. For example, ferrite and austenite phases are enantiotropic in ferrous alloys.

Encapsulation – The encasement of radioactive waste (normally low level and intermediate level wastes) by an encapsulent such as concrete.

Enclosed industrial control panels – An enclosed industrial control panel is comprised of the enclosure, all components located within the enclosure, and all components mounted to the walls of the enclosure. The construction of the entire unit has been inspected, including its ability to safely function within the specified marked voltage, current, and short circuit current ratings (SCCRs).

End – It is a strand of roving consisting of a given number of filaments gathered together. The group of filaments is considered an ‘end’ or strand before twisting, a ‘yarn’ after twist has been applied. It is an individual warp yarn, thread, fiber, or roving.

End approach – End approach describes the minimum horizontal distance, parallel to the runway, between the outermost extremities of the crane and the centre line of the hook.

End-centered – It consists of having an atom or group of atoms separated by a translation of the type 1/2, 1/2, 0 from a similar atom or group of atoms. The number of atoms in an end-centered cell is needed to be a multiple of 2.

End count – It is an exact number of ends supplied on a ball of roving.

End grain – It is the grain flow lines which intersect with the exposed surface of the ends of bar stock, tubing, or the parting lines of forgings. A long, narrow test sample sectioned so that the grain is parallel to the longitudinal axis of the sample has no exposed end grain, except at the extreme ends. In contrast, a corresponding sample cut in the transverse direction has end-grain exposure at all points along its length. End grain is especially pronounced in the short-transverse direction on die forgings designed with a flash line.

End-grain attack – It is the preferential corrosive attack of grains exposed by cutting through the cross section or at the parting lines of forgings.

Endless rolling technology – It is a process method for the rolling of the bars and rods (also known as long products) from the billets. It consists of a welding arrangement designed to endlessly join billets together in order to provide a continuous supply of material to the rolling mill train. It is enabled by welding of the billets which come from a reheating furnace at the upstream side of the stands of rolling mill train. In fact, the joining of the tail end of the billet being rolled and the head end of the billet to be rolled is one of the key aspects of the endless rolling technology.

End mark – It is a roll mark caused by the end of a sheet marking the roll during hot rolling or cold rolling.

End milling – It is a method of machining with a rotating cutting tool with cutting edges on both the face end and the periphery.

End 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.

Endogenic ore deposits – Endogenic ore deposits are normally intimately associated with geological structures. Ore deposits are grouped as endogenetic when their origin is associated with thermal processes and when, in general, they are clearly related to magmatic and tectonic events.

Endogenous inclusions – These are inclusions which originate from the steelmaking process.

Endothermic atmosphere – It is a gas mixture produced by the partial combustion of a hydrocarbon gas with air in an endothermic reaction. It is also known as endogas.

Endothermic reaction – It is the designating or pertaining to a reaction which involves the absorption of heat.

End-quench hardenability test – It is a laboratory procedure for determining the hardenability of a steel or other ferrous alloy. It is widely referred to as the Jominy test. Hardenability is determined by heating a standard sample above the upper critical temperature, placing the hot sample in a fixture so that a stream of cold water impinges on one end, and, after cooling to room temperature is completed, measuring the hardness near the surface of the specimen at regularly spaced intervals along its length. The data are normally plotted as hardness against distance from the quenched end.

End return – It is the continuation of a fillet weld around a corner of a member as an extension of the principal weld.

End state – It is the state and condition to which the site of a designated nuclear power station or facility is required to be restored at the time of decommissioning for the unrestricted use of a site.

End trucks – They are located on either side of the crane bridge. They house the wheels on which the entire crane travels. It is an assembly consisting of structural members, wheels, bearings, and axles etc., which supports the bridge girder(s) or the trolley cross member(s).

Endurance – It is the capacity of a material to withstand repeated application of stress.

Endurance limit – It is an obsolete term which is used to describe a characteristic in components subject to fatigue cracking. It does not reflect the current understanding of how fatigue cracks initiate and grow. It referred to the maximum stress below which a material can presumably endure an infinite number of stress cycles. If the stress is not completely reversed, the value of the mean stress, the minimum stress, or the stress ratio also should be stated.

Endurance ratio – It is the ratio of the endurance limit for completely reversed flexural stress to the tensile strength of a given material.

Energiron direct reduction technology – It is a gas based direct reduction technology. Energiron process converts iron ore pellets or lumps into metallic iron. It uses the HYL direct reduction technology developed jointly by Tenova and Danieli and is a competitive and environmentally clean solution for lowering the liquid steel production cost. It uses a simple plant configuration, has flexibility for using different sources of reducing gases and has a very efficient and flexible use of iron ores. A key factor in many of the process advantages is directly related to its pressurized operation.

Energy – It is the quantitative property which is transferred to a body or to a physical system, _recognizable in the performance of work and in the form of heat and light. Energy is a conserved quantity. The law of conservation of energy states that energy can be converted in form, but not created or destroyed. Matter and energy may also be converted to one another. The unit of measurement for energy in the International System of Units (SI) is the joule (J). Forms of energy include the kinetic energy of a moving object, the potential energy stored by an object (for instance due to its position in a field), the elastic energy stored in a solid object, chemical energy associated with chemical reactions, the radiant energy carried by electromagnetic radiation, the internal energy contained within a thermo-dynamic system, and rest energy associated with an object’s rest mass.

Energy audit – Energy audit is the inspection, examination, analysis and evaluation of the physical and financial processes of an industrial plant relating to the use of the energy. The aim of the energy audit is to systematically identify the potential for saving energy and make recommendations for improvement. It is a key requirement for an industrial plant. It helps the plant management to identify and realize energy efficiency improvements in a systematic way. It assists the plant management in understanding how it uses energy and helps to identify the areas where waste occurs and where opportunities for improvement exist.

Energy conservation – It plays a fundamental role in an industrial plant. This approach to the processes of the plant helps the plant management to focus on to control activities and practices for the reduction of the energy wastes. Energy conservation not only has a positive effect on the energy efficiency, but it also implies a reduced use of energy sources, possibly integrated with the recovery of the waste energy. The goals and objectives of energy conservation activities in a plant include (i) provision of the opportunities to decrease the specific energy consumption, (ii) provision of good practices to utilize energy sources more effectively, (iii) provision of good practices to recover waste energy (heat, gas) wherever practical, (iv) to enable the plant management to develop plans for plant energy intensity reduction, and (v) to use benchmarking technique for the prioritization of investments to maximize the energy conservation and adopt practices with the biggest impact.

Energy-dispersive spectroscopy (EDS) – It is a method of x-ray analysis which discriminates by energy levels the characteristic x-rays emitted from the sample. Compare with wavelength-dispersive spectroscopy.

Energy efficiency – In an industrial plant, energy efficiency is the practice of reducing manufacturing energy consumption levels through a broad range of technologies, methodologies and practices. There are several reasons for the plant management to make the plant become energy efficient which include (i) rising energy costs, (ii) rising inflation rates, (iii) environmental concerns, (iv) to improve competitiveness, and (v) to create economic stability.

Energy management approach – Under this approach, the plant management develops procedures and system of recording and analyzing the operating data. The employees are thoroughly trained in these procedures and system. By adopting this approach, there is normally a substantial reduction in the operating mistakes by the operators and the processes run in more stable mode, which in turn helps in the energy conservation. A sound energy management system creates a foundation for positive change and provides guidance for managing energy throughout the plant resulting into continuous improvements towards the conservation of energy. Energy conservation under energy management occurs because of existence of a strong organizational commitment. Energy management system helps to ensure that energy efficiency improvements do not just happen on a one-time basis, but rather are continuously identified and implemented.

Energy management system – It supports an organization to use energy more efficiently. The organization specifies the requirements for establishing, implementing, maintaining, and improving an energy management system, whose purpose is to enable an organization to follow a systematic approach in achieving continual improvement of energy performance, including energy efficiency, energy security, energy use, and consumption. The system aims to help the organization continually reduce the energy use, and hence the energy costs and the greenhouse gas emissions.

Energy optimizing furnace (EOF)– It is a furnace for the primary steelmaking.  It is a melting / refining furnace for the production of liquid steel. It is having a scrap pre-heater.  The basic principle consists of working with combined submerged and atmosphere oxygen blown in an initial charge containing hot metal, preheated solid scrap and fluxes for slag formation. Scrap is preheated to around 850 deg C to 900 deg C by the sensible heat in the off gas in one or two chambers located above the furnace roof. Blown submerged oxygen reacts with the carbon from hot metal and generates carbon mono-oxide bubbles which travel through the liquid bath to the furnace atmosphere. Here carbon mono-oxide is burnt to carbon di-oxide by the oxygen blown through atmospheric injectors and supersonic lances. The bubbling of carbon mono-oxide generates a very strong stirring action and increases significantly the bath surface. This allows transfer of a good quantity of heat to the bath. The process also constitutes de-slagging and formation of the secondary slag.

Engineered plastic – It is a material which has been made by specific design and through use of particular monomers and monomer sequences to produce a plastic with desired properties, possibly for a specific application.

Engineered safety features – These are engineered systems which are important to the safety of the plant. These systems relate to shutting down the reactor, provision of cooling, mitigating the effects of a loss of reactor coolant accident (LOCA), or minimizing offsite release.

Engineering controls – A category of hazard control which uses physical / engineering methods to eliminate or minimize the hazard. Examples of engineering controls include ventilation, isolation, elimination, enclosure, substitution and design of the work-place or equipment.

Engineering design specification – it is a detailed description of the intended and unintended uses which product is going to be put to, a list of any special features needed or desired, and a detailed list of the functional requirements with qualitative or quantitative goals and limits for each. It is also known as product design specification.

Engineering drawing – It is a two-dimensional representation of three-dimensional objects. In general, it provides necessary information about the shape, size, surface quality, material, and manufacturing process, etc. of the object. It is the graphic language from which a trained person can visualize objects. Engineering drawing is called the universal language of engineers.  It is also known as technical drawing. It is an effective way of communicating technical ideas and is a necessary tool in engineering design where the majority of the design processes are graphically based. Engineering drawings are used in the design process for visualization, communication, and documentation.

Engineering plastics – It is a general term covering all plastics, with or without fillers or reinforcements, which have mechanical, chemical, and thermal properties suitable for use as construction materials, machine components, and chemical processing equipment components. Engineering plastics include acrylonitrile-butadiene-styrene, acetal, acrylic, fluorocarbon, nylon, phenoxy, polybutylene, polyaryl ether, polycarbonate, polyether (chlorinated), polyether sulfone, polyphenylene oxide, polysulfone, polyimide, rigid polyvinyl chloride, polyphenylene sulfide, thermoplastic urethane elastomers, and several other reinforced plastics.

Engineering steel chains – These chains have been developed for greater strength, speed, shock resistance, and for better dimensional control. They operate dependably in the most demanding conditions. Several different types of engineering steel chains are used in a wide variety of applications. Most engineering steel chains are used in conveyors, bucket elevators, and tension linkages. Only a few are used in drives. The main design considerations for these chains are tensile loads, several types of wear, lubrication, and environment. The main design considerations for an engineering steel chain to be used on a drive include the various tensile loads, certain types of wear, roller and bushing impact, and galling.

Engineering strain (e) – It is a term sometimes used for average linear strain or conventional strain in order to differentiate it from true strain. In tension testing it is calculated by dividing the change in the gauge length by the original gauge length.

Engineering stress (s) – It is a term sometimes used for conventional stress in order to differentiate it from true stress. In tension testing, it is calculated by dividing the breaking load applied to the sample by the original cross-sectional area of the sample.

Engineering stress-strain curve – In the conventional engineering tensile test, an engineering stress-strain curve is constructed from the load-elongation measurements made on the test sample. The engineering stress (s) used in this stress-strain curve is the average longitudinal stress in the tensile sample which is got by dividing the load by the original area of the cross section of the sample. The strain (e) used for the engineering stress-strain curve is the average linear strain, which is got by dividing the elongation of the gauge length of the sample by its original length.

Engine oil – It is an oil which is used to lubricate an internal combustion engine.

Engler viscosity – It is a commercial measure of viscosity expressed as the ratio between the time in seconds needed for 200 cubic centimeters of a fluid to flow through the orifice of an Engler viscometer at a given temperature under specified conditions and the time needed for 200 cubic centimeters of distilled water at 20 deg C to flow through the orifice under the same conditions. It is desired that standard viscosity units are used.

Enriched uranium – It is the uranium in which the percent composition of Uranium-235 has been increased from the natural level of around 0.7 % through the process of isotope-separation.

Enrichment – It is the process used to increase the abundance of fissile isotopes in an element, such as naturally-occurring uranium.

Enterprise – A company, business, firm, institution or organization designed to provide goods and / or services to the consumers. It can imply for-profit business, not-for-profit organizations, agencies, or self-employed individuals.

Environment – It is the complex of physical, chemical, and biotic factors (climate, soil, and living things) which act upon metal and ultimately affect the corrosion rate.

Enthalpy – It is the sum of a thermodynamic system’s internal energy and the product of its pressure and volume. It is a state function in thermodynamics used in several measurements in chemical, biological, and physical systems at a constant external pressure, which is conveniently provided by the large ambient atmosphere.

Entomb – It is a method of decommissioning whereby the radioactive material is encased in a structurally long-lived material, such as concrete. The entombment structure is appropriately maintained and continued surveillance is carried out until the radioactivity decays to a level permitting decommissioning and ultimate unrestricted release of the property.

Entraining velocity – It is the velocity of a liquid at which bubbles of gas are carried along in the stream.

Entrance burr – It is the burr formed on the surface at which the cutting tool or its teeth enters the work-piece.

Entropy – It is the measure of a system’s thermal energy per unit temperature which is unavailable for doing useful work. Because work is obtained from  ordered molecular motion, the quantity of entropy is also a measure of the  molecular disorder, or randomness, of a system. It is a scientific concept which is normally associated with a state of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields. Entropy is central to the second law of thermodynamics, which states that the entropy of an isolated system left to spontaneous evolution cannot decrease with time. As a result, isolated systems evolve toward thermodynamic equilibrium, where the entropy is highest. A consequence of the second law of thermodynamics is that certain processes are irreversible.

Environment – It is the complex of physical, chemical, and biotic factors (climate, soil, and living things) which act upon metal and ultimately affect the corrosion rate.

Environmental acceptable hydraulic fluids – These fluids are basically used in the application where there is a risk of leakage or spills into the environment, which can cause some damage to the environment. These fluids are not harmful to the aquatic creatures and they are bio-degradable. These fluids are used in forestry, lawn equipment, off-shore drilling, dams and maritime industries. The ISO have classified these fluids as HETG (based on natural vegetable oils), HEES (based on synthetic esters), HEPG (poly-glycol fluids) and HEPR (polyalphaolefin types).

Environmental audit – It is a methodical examination involving analyses, tests, and confirmations to verify whether the emissions, discharges and waste management of the industrial plant comply with statutory requirements, internal norms and accepted practices. During the environmental audit, procedures and practices of the plant are also examined. Environmental audits are normally voluntary in nature and they are not the requirement which is imposed by the regulating agencies.

Environmental clearance (EC) – it is the clearance for the project from the environment regulatory authorities. It is normally given after the project authorities have made and submitted an acceptable report for the environmental impact assessment and environmental management plan.

Environmental clearance (EC) process – The environmental clearance process has several steps which are required to be followed. These steps are (i) screening, (ii) scoping and consideration of alternatives, (iii) baseline data collection, (iv) impact prediction, (v) assessment of alternatives, description of mitigation measures and environmental impact statement, (vi) public hearing, (vii) environment management plan, (viii) decision making, (ix) monitoring of the clearance conditions.

Environmental cracking – It is the brittle fracture of a normally ductile material in which the corrosive effect of the environment is a causative factor. Environmental cracking is a general term which includes corrosion fatigue, high temperature hydrogen attack, hydrogen blistering, hydrogen embrittlement, liquid metal embrittlement, solid metal embrittlement, stress-corrosion cracking, and sulphide stress cracking. Several other terms have been used in the past in connection with environmental cracking, but have now become obsolete. These terms are caustic embrittlement, delayed fracture, season cracking, static fatigue, stepwise cracking, sulphide corrosion cracking, and sulphide stress-corrosion cracking.

Environmental impact assessment (EIA) – It is a process which predicts the effects of proposed developments on the environment which informs decision-makers in relation to planning permissions, consents, licenses and other statutory approvals. The purpose of environmental impact assessment is to identify and evaluate the potential impacts (beneficial and adverse) of the planned project on the environmental system. It is a useful tool for decision making based on understanding of the environmental implications including social, cultural and aesthetic concerns which can be integrated with the analysis of the project costs and benefits. It is also a system-wide determination of the multiple impacts which an engineering product has on the environment.

Environmental impact assessment study – It is a written report, compiled prior to a plant approval decision, which examines the effects proposed plant is going to have on the natural surroundings.

Environmental laws – These are laws which protect the environment. Environmental law is the collection of laws, regulations, agreements and common law which governs how humans interact with their environment.

Environmentally assisted cracking – It is also called environmentally induced cracking. It is the forms of corrosion which produce cracking of metals as a result of exposure to their environment. This cracking can take the form of relatively slow, stable crack extension or, as is frequently the case, unpredictable catastrophic fracture. It is the brittle fracture of a normally ductile material in which the corrosive effect of the environment is a causative factor. Environmental cracking is a general term which includes corrosion fatigue, high temperature hydrogen attack, hydrogen blistering, hydrogen embrittlement, liquid metal embrittlement, solid metal embrittlement, stress-corrosion cracking, and sulphide stress cracking. In general, these different phenomena show several similarities, as well as  there are several differences encountered between these different  forms of environmentally assisted cracking, and in fact, substantial differences are observed for behaviour of metals and alloys within a specific form of cracking.

Environmentally assisted embrittlement – It is the embrittlement because of the environment conditions. The forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid metal embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress-corrosion cracking.

Environmental management plan (EMP) – It describes how an action might impact on the natural environment in which it occurs and set out clear commitments from the people taking the action on how those impacts are avoided, minimized and managed so that they are environmentally acceptable. It is needed for the formulation, implementation and monitoring of environmental protection measures during and after commissioning of the project. Environmental management plan is required to indicate the details of the various measures already incorporated in the project or are proposed to be taken including cost components. Cost of measures for environmental safeguards is to be treated as an integral component of the project cost.

Environmental management system (EMS) – It is a systematic approach for incorporating energy and environmental goals and priorities (such as energy use and regulatory compliance) into the routine operations. While some sort of de-facto system is inherent to the organization which is to meet the requirements of energy and environment as part of its daily operations, it is normally accepted as a valuable step to formalize the approach by documenting it. Not only does documentation of the system ensure consistency over time and across employees, there is a growing body of evidence indicating that there is considerable value in defining a systematic approach to managing energy and environmental goals. Environmental management system is also a systematic approach of meeting the goal and objectives of the organization. The focus of the environmental management system is on the quality principles for improving the environment.

Environmental permit – It is permit issued by the Environment agency to control the environmental impacts associated with, among other issues, discharges and waste. It is also known as environmental consent.

Environment plan drawing – Some projects are built around rivers or streams. In that case, the environmental plan drawing provides insights into how erosion and sedimentation is to be managed. These drawings also talk about plant effluent removal procedures and chemical disposal mechanisms. Moreover, it also has the procedures and plans to reduce the harmful effects.

Environmental regulation (ER) – It is any state intervention in the market in order to protect the environment, be it by general rules or individual action. The basic orientation of ER depends on how it perceives nature such as ‘fate’, a resource, an ‘environment’, or a bio-sphere.

EPC contract – EPC stands for ‘engineer, procure and construct’. It describes a contract under which an engineering contractor undertakes to (i) design a process plant or power plant etc., or works with a heavy engineering element, normally to meet a specified level of performance, (ii) procure all components comprised in the design, and (iii) physically construct and test the plant. The equivalent term used in relation to more standard construction (e.g. housing, office blocks etc.) is ‘design-and-build’.

Epichlorohydrin – It is the basic epoxidizing resin intermediate in the production of epoxy resins. It contains an epoxy group and is highly reactive with polyhydric phenols such as bisphenol A.

Epigenetic – It is the orebodies formed by hydrothermal fluids and gases that were introduced into the host rocks from elsewhere, filling cavities in the host rock.

Epitaxy – It is the growth of an electro-deposit or vapour deposit in which the orientation of the crystals in the deposit are directly related to crystal orientations in the underlying crystalline substrate.

Epithermal deposit – It is a mineral deposit consisting of veins and replacement bodies, normally in volcanic or sedimentary rocks, containing precious metals or, more rarely, base metals.

Epoxide – It is the compound containing the oxirane structure, i.e., a three-member ring containing two carbon atoms and one oxygen atom. The most important members are ethylene oxide and propylene oxide.

Epoxide equivalent weight (EEW) – It is the weight of a resin (in grams) which contains one gram equivalent of epoxy.

Epoxy – It is the resin formed by the reaction of bisphenol and epichlorohydrin.

Epoxy plastic – It is a polymerizable thermoset polymer containing one or more epoxide groups and curable by reaction with amines, alcohols, phenols, carboxylic acids, acid anhydrides, and mercaptans. It is an important matrix resin in composites and structural adhesive.

Epoxy resins – These are a class of thermoset materials which are used extensively in structural and specialty composite applications since they offer a unique combination of properties which are not attainable with other thermoset resins. They are available in a wide variety of physical forms from low-viscosity liquid to high-melting solids. They are amenable to a wide range of processes and applications. Epoxy resins offer high strength, low shrinkage, excellent adhesion to different substrates, effective electrical insulation, chemical and solvent resistance, low cost, and low toxicity. They are easily cured without evolution of volatiles or by-products by a broad range of chemical specie. Epoxy resins are also chemically compatible with majority of the substrates and tend to wet surfaces easily, making them especially well-suited to composites applications. Epoxy resins are routinely used as adhesives, coatings, encapsulates, casting materials, potting compounds, and binders

Epsilon – It is a designation normally assigned to intermetallic, metal-metalloid, and metal-non-metallic compounds found in ferrous alloy systems, e.g., Fe3Mo2, FeSi, and Fe3P.

Epsilon carbide – It is the carbide with hexagonal close-packed lattice which precipitates during the first stage of tempering of primary martensite. Its composition corresponds to the empirical formula Fe2.4C.

Epsilon structure – It is structurally analogous close-packed phases or electron compounds which have ratios of seven valence electrons to four atoms.

Equal percentage valve – It is a control valve which produces equal valve stroke for equal increments in valve travel. This is the most common type of valve.

Equator – In filament winding, it is the line in a pressure vessel described by the junction of the cylindrical portion and the end dome. It is also called tangent line or point.

Equiaxed grain structure – It is a structure in which the grains have approximately the same dimensions in all directions.

Equilibrium – It is the dynamic condition of physical, chemical, mechanical, or atomic balance which appears to be a condition of rest rather than one of change.

Equilibrium, alloy phases – There are three types of equilibria namely stable, meta-stable, and unstable. Stable equilibrium exists when the object is in its lowest energy condition. Meta-stable equilibrium exists when additional energy is to be introduced before the object can reach true stability. Unstable equilibrium exists when no additional energy is needed before reaching meta-stability or stability. Although true stable equilibrium conditions rarely exist in metal objects, the study of equilibrium systems is extremely valuable, since it constitutes a limiting conditions from which actual conditions can be estimated.

Equilibrium diagram – It is a graph of the temperature, pressure, and composition limits of phase fields in an alloy system as they exist under conditions of thermodynamical equilibrium. In metal systems, pressure is normally considered constant.

Equilibrium electrode potential – It is a static electrode potential when the electrode and the electrolyte are in equilibrium with respect to a specified electro-chemical reaction.

Equilibrium (reversible) potential – It is the potential of an electrode in an electrolytic solution when the forward rate of a given reaction is exactly equal to the reverse rate. The equilibrium potential can only be defined with respect to a specific electro-chemical reaction.

Equipment drawing – It is pertaining to equipment parts or components. It is presented through a number of orthographic views, so that the size and shape of the component is fully understood. Part drawings and assembly drawings belong to equipment drawing.

Equipment erection – It involves the assembly and installation of simple, large, and complex equipment. The process is complex and challenging which needs precise planning and execution. This needs expertise in engineering principles and techniques along with skilled workmen and engineers.

Equipment foundation – It is the super-structure of vibrating and rotating equipments. It essentially consists of a mass of reinforced concrete. Design of equipment foundation involves consideration of static and dynamic loads. Equipment foundation is specially designed to meet machinery loads, movements and other actions. These specific foundations can help protect flooring as you use machinery, enhancing working conditions for operators by absorbing vibrations and frequencies.

Equipment foundation system – In a broader sense, it comprises of equipment, supported by foundation resting over soil subjected to dynamic loads namely (i) generated by equipment itself, (ii) applied externally, or (iii) caused by external sources and transmitted through soil.

Equivalent radial load – It is the level of constant radial load on a rolling-element bearing which, when the bearing is stationary with respect to the outer race, produces the same rating life as a given combination of radial and thrust loads under the same conditions of operation.

Equivalent round – It is the diameter of a circle having a circumference equal to the outside perimeter of other than round tube.

Erection – It means all the on-site erection and installation activities, as applicable, including fabrication, assembly, construction, alignment, leveling, installation, interfacing, piping, welding, preheating, annealing, insulating, lagging, painting, grouting, fastening and anchoring, clearing, checking, oil filling and treating, adjusting, and quality testing.

Erection contract – It describes a contract under which an engineering contractor undertakes erection activities at site.

Erection drawing – An erection drawing provides information for properly positioning and installing items relative to their supporting structure and adjacent items. This information includes dimensional data, hardware descriptions, and general configuration information for the installation site. The erection drawing is prepared to provide detailed installation information for (i) functionally related items (such as a control system, electrical system, or hydraulic system) which cannot be effectively shown on an assembly drawing of the item to which it belongs, or (ii) a part or assembly which is so large or complex that the major assembly drawing cannot accommodate all relevant data. An erection drawing normally includes (i) overall and principal dimensions in sufficient detail to establish space requirements for installation, operation, and servicing including clearances for opening of doors, removal of plug-in units and travel or rotation of any moving parts (including the centres of rotation, angles of elevation and depression), (ii) interface mounting and mating information (e.g. locating dimensions for attaching hardware), (iii) interfaces for pipe and cable attachments, (iv) information necessary for preparation of foundation plans including mounting details, (v) references to interconnecting and cabling data and to associated lists, (vi) identification of and requirements for installation items not included in the parts list of the using assembly drawing, (vii) reference to the assembly drawing of the major item being installed, (viii) a parts list specifying the items to be installed thus establishing item identification for a work package, and (ix) supporting structure or associated items which are not included in the installed items.

Erichsen cupping test – It is a which deep-drawing test is used to determine the stretch-forming capacity of sheet metals, which have a thickness of 0.1 mm to 2 mm and a width of 90 mm or more. This cupping test is used to assess the ductility of sheet metal. The method consists of forcing a conical or hemispherical-ended plunger into the sample and measuring the depth of the impression at fracture.

Erosion – It is the loss of material from a solid surface because of the relative motion in contact with a fluid which contains solid particles. Erosion in which the relative motion of particles is nearly parallel to the solid surface is called abrasive erosion. Erosion in which the relative motion of the solid particles is nearly normal to the solid surface is called impingement erosion or impact erosion. Erosion is also the progressive loss of original material from a solid surface because of the mechanical interaction between that surface and a fluid, a multicomponent fluid, and impinging liquid, or solid particles. It is also the loss of material from the surface of an electrical contact because of an electrical discharge (arcing).

Erosion (brazing) – It is a condition caused by dissolution of the base metal by molten filler metal resulting in a reduction in the thickness of the base metal.

Erosion-corrosion – It is a conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of material.

Erosion (erosive) wear – It is (i) loss of material from a solid surface because of the relative motion in contact with a fluid which contains solid particles. Erosion in which the relative motion of particles is nearly parallel to the solid surface is called abrasive erosion. Erosion in which the relative motion of the solid particles is nearly normal to the solid surface is called impingement erosion or impact erosion, (ii)

progressive loss of original material from a solid surface due to mechanical interaction between that surface and a fluid, a multi-component fluid, and impinging liquid, or solid particles, and (iii) loss of material from the surface of an electrical contact because of an electrical discharge (arcing). Because of the broad scope of this term, it is desired that it normally be qualified to indicate the relevant mechanism or context, e.g., impingement erosion. abrasive erosion, and so forth.

Erosion rate – It is a determination of the rate of loss of material (erosion) with exposure duration. In

certain contexts, it is given by the slope of the cumulative erosion-time curve.

Erosion rate-time curve – It is a graph of instantaneous erosion rate against exposure duration, normally got by numerical or graphical differentiation of the cumulative erosion-time curve.

Erosivity – It is the characteristic of a collection of particles, liquid stream, or a slurry that expresses its tendency to cause erosive wear when forced against a solid surface under relative motion.

Error – It is a mistake or error of judgement leading to action resulting in an accident and its subsequent effects. In the process control systems, error is defined as the difference between set point and process variable and is given by the equation ‘error = set point – process variable’. In a statistical interpretation, the word ‘error’ is used to denote the difference between an observed value and its ‘expected’ value as predicted or explained by a model. In addition, errors occur in data collection, sometimes resulting in outlying observations. Finally, type I and type II errors refer to specific interpretive errors made when analyzing the results of hypothesis tests.

Error (of measurement) – It is the result of a measurement minus a true value of the measurement. It can also be expressed as a percentage.

Error rate prediction – It is a forecast of the possibility of error based on statistical data.

Escape peak – It is an artifact observed in x-ray analysis. It is manifested as a peak at energy 1.74 keV (the silicon K-alpha peak) less than the major line detected. Escape peaks can be avoided by increasing the accelerating voltage.

Essential service water system – This system circulates the water which cools the plant’s heat exchangers and other components before dissipating the heat into the environment. Since this includes cooling the systems which remove decay heat from both the primary system and the spent fuel rod cooling ponds, the essential service water system is a safety-critical system. Since the water is frequently drawn from an adjacent river, the sea, or other large body of water, the system can be fouled by seaweed, marine organisms, oil pollution, ice and debris. In locations without a large body of water in which to dissipate the heat, water is recirculated through a cooling tower.

Estimate methods – These are techniques for calculating the quantities of different work items. These estimation techniques enable a person to plan for resource allocation, provide better forecasts, and budget the funds and resources needed for project success more accurately.

Estimation – Estimation is the process by which sample data are used to indicate the value of an unknown quantity in a population. The results of estimation can be expressed as a single value, known as a point estimate. It is normal to also give a measure of precision of the estimate. This is called the standard error of the estimate. A range of values, known as a confidence interval can also be given.

Eta layer – It is the fourth outer layer of the galvanized coating solely comprised of zinc.

Eta, statistics – It is an index which indicates the degree of a curvilinear relationship.

Etch – It is a roughened surface produced by chemical or electro-chemical means. It also means to dissolve unevenly a part of the surface of a metal.

Etchant – It is a chemical solution used to etch a metal to reveal structural details. It is also a solution used to remove, by chemical reaction, the unwanted portion of material from a printed circuit board. It also means hydro-fluoric acid or other agent used to attack the surface of glass for marking or decoration.

Etch cleaning – It consists of removing soil by dissolving away some of the underlying metal.

Etch cracks – These are shallow cracks in hardened steel containing high residual surface stresses, produced by etching in an embrittling acid.

Etch figures – These are the characteristic markings produced on crystal surfaces by chemical attack, normally having facets parallel to low-index crystallographic planes.

Etching – It is subjecting the surface of a metal to preferential chemical or electrolytic attack in order to reveal structural details for metallographic examination. It is also chemically or electro-chemically removing tenacious films from a metal surface to condition the surface for a subsequent treatment, such as painting or electro-plating.

Etching (pitting) -It is the localized attack of metal surfaces. Controlled etching of metals improves the adhesion of organic coatings. By contrast, uncontrolled etching of metals by an acid can cause damage by weakening the crystal structure.

Etch pits – It is the localized corrosion attack at the microscopic scale. It is typically seen on a polished and etched metallographic specimen. Etch pits typically have recognizable, simple geometric shape (square, rectangle, and triangle) and hence reveal, in a qualitative way, the orientation of a grain. It is also a conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of material.

Etch priming – Some galvanized coating primers contain acid etching components to improve adhesion. These are application critical products which needs experience in their application.

Etch rinsing – It is pouring etchant over a tilted surface until the desired degree of attack is achieved. It is used for etchants with severe gas formation.

Ethernet protocol – It is defined as a communication protocol that operates at layer 2 of the open system intercommunication (OSI) seven-layer model, playing a crucial role in data networks by facilitating the transmission of data packets between devices. It has evolved from shared coaxial cable to switch-based protocols, incorporating technologies like Spanning Tree Protocol and virtual local area network (VLAN) for reliability and segmentation of broadcast domains.

Ethyl silicate – It is a strong bonding agent for sand and refractories used in preparing moulds in the investment casting process.

Ethylene – propylene – diene rubber – It is known as EPDM (ethylene propylene diene monomer) rubber. The temperature resistance of this rubber is similar to butyl rubber but with a considerable higher resistance to wear and tear. It has also got a better ozone resistance.

Euler angles – These are three angular parameters which specify the orientation of a body with respect to reference axes.

Eutectic – It is an isothermal reversible reaction in which a liquid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. It is also an alloy having the composition indicated by the eutectic point on a phase diagram. Eutectic is also an alloy structure of intermixed solid constituents formed by a eutectic reaction frequently in the form of regular arrays of lamellas or rods.

Eutectic alloy – It is the alloy composition which freezes at constant temperature similar to a pure metal. It is the lowest melting (or freezing) combination of two or more metals. The alloy structure (homogeneous) of two or more solid phases formed from the liquid eutectically.

Eutectic arrest – In a cooling or heating curve, it is an approximately isothermal segment corresponding to the time interval during which the heat of transformation from the liquid phase to two or more solid

phases are evolving.

Eutectic carbide – It is the carbide formed during freezing as one of the mutually insoluble phases participating in the eutectic reaction of ferrous alloys.

Eutectic-cell etching – It consists of the dDevelopment of eutectic cells (grains).

Eutectic melting – It is the melting of localized microscopic areas whose composition corresponds to that of the eutectic in the system.

Eutectic point – It is the composition of a liquid phase in univariant equilibrium with two or more solid phases. It is also the lowest melting alloy of a composition series.

Eutectoid – It is an isothermal reversible reaction in which a solid solution is converted into two or more intimately mixed solids on cooling, the number of solids formed being the same as the number of components in the system. It is also an alloy having the composition indicated by the eutectoid point on a phase diagram. Eutectoid is an alloy structure of intermixed solid constituents formed by a eutectoid reaction.

Eutectoid point – It is the composition of a solid phase which undergoes univariant transformation into two or more other solid phases upon cooling.

Eutectoid steels –These are the steels representing the eutectoid composition of the iron-carbon system with around 0.80 % to 0.83 % C and the eutectoid temperature of around 723 deg C. Such steels in the annealed condition consist exclusively of pearlite. The presence of certain elements, such as Ni or Cr, lowers the eutectoid carbon content.

Eutrophication – It is a process in which nutrients accumulate in a body of water, resulting in an increased growth of microorganisms which can deplete the oxygen in water. The discharge of nitrogenous and phosphorous compounds into receiving water-bodies can alter their fertility. Enhanced fertility can lead to excessive plant growth. The latter can include algal growth. The subsequent impact of such growth on a water-body can include increased turbidity, oxygen depletion, and toxicity issues. Algal growth in unpolluted water-bodies is normally limited since the water is nutrient limiting. While nutrients include macro-nutrients like nitrogen, phosphorous, and carbon, and micro-nutrients like cobalt, manganese, calcium, potassium, magnesium, copper, and iron which are needed only in very small quantities, the focus in concerns over eutrophication is on phosphorous and nitrogen since the quantities of the other nutrients in the natural environment are frequently inherently adequate.

Evaluation – It is a systematic determination and assessment of a subject’s merit, worth and significance, using criteria governed by a set of standards. It can assist an organization, programme, design, project or any other intervention or initiative to assess any aim, realizable concept / proposal, or any alternative, to help in decision-making, or to generate the degree of achievement or value in regard to the aim and objectives and results of any such action that has been completed.

Evaluation process – It goes through four distinct phases namely planning, implementation, completion, and reporting. While these mirror common programme development steps, it is important to remember that a person’s evaluation efforts may not always be linear.

Evaluation of property data – It is the process of establishing the accuracy and integrity of property data by appraisal of the data presented, assessment of the experimental technique and its associated errors, and checking for consistency of values and comparison with other experimental or theoretical values.

Evaluation report – It is a document which distills and articulates the outcomes and findings of an evaluation process, incorporating both qualitative and quantitative aspects. It is tailored to different audiences and serves as a basis for informed decision-making in programming choices and practices.

Evaporation – It is the vapourization of a material by heating, normally in a vacuum. In electron microscopy, this process is used for shadowing or to produce thin support films by condensation of the vapours of metals or salts.

Evaporative deposition – It is the techniques of condensing a thin film of material on a substrate. The entire process takes place in a high vacuum. The source material may be radioactively heated by bombardment with electrons (electron-beam radiation) or can be heated by thermal-conduction techniques.

Evaporative pattern (mould) casting process – It is a type of casting process which uses a pattern made from a material which evaporates when the liquid metal is poured into the mould cavity. This means that there is no need to remove the pattern material from the mould before casting. The most common evaporative-pattern material used is polystyrene foam. The two main processes are lost foam casting and full mould casting.

Evaporative stave cooling, natural (NEVC) – It is a technique where boiler quality water is introduced into the bottom row of staves and flows by natural mean up the vertical cooling circuits. As the process heat conducts through the stave and cooling pipe into the water, the water in turn heats up. As the water warms, it expands. Since cooler water is being introduced below, the warm water tends to move upwards. At some point in the vertical cooling circuit, the water is at the boiling point. As the water changes its phase to steam, due to the latent heat of vapourization, additional heat is absorbed (driving the phase change). After boiling begins, two-phase flow (water and steam mixture) ascends the cooling pipes to the top of the furnace. Normally located on the furnace top platform are steam separator drums used to extract and vent the steam to atmosphere. Make-up water is introduced to the drum (to replace the discharged steam). The water is piped back by gravity to the furnace bottom and is fed once more to the staves. This cooling technique is very efficient and has low operating costs. There is no pumping equipment.

Evaporative stave cooling, forced (FEVC and FCWC)– It is the improvements in natural evaporative stave cooling. In this system the flow of the cooling water gets a boost with recirculating pumps (forced evaporative cooling, FEVC) in order to ensure uniform cooling water flow and to cool the recirculating water (forced cold water cooling, FCWC).

Evaporator – It is an equipment wherein evaporation occurs, i.e. liquid is evaporated from a thin (low-density) feed material in order to produce a denser or thicker product (concentrate). The feed can be a solution, slurry or suspension of solid materials in a liquid.

Event – An event is an occurrence unintended by the operator, including operating error, equipment failure, or other mishap, and deliberate action on the part of others, the consequences or potential consequences of which are not negligible from the point of view of protection and safety.

Even tension – It is the process whereby each end of roving is kept in the same degree of tension as the other ends making up that ball of roving.

Event tree analysis (ETA) – It is a binary logic tree for tracing all the possible consequences of an event. Unlike the fault tree, the event tree starts with an initiating event and traces all possible consequences. It is also a graphical method of exploring how an initiating (hazardous) event can lead to an accident through a set of further events. The method allows the exploration of barriers to escalation of the hazard (mitigations) and the calculation of the relative likelihoods of different outcomes.

Ewald sphere – It is a geometric construction, of radius equal to the reciprocal of the wave-length of the incident radiation, with its surface at the origin of the reciprocal lattice. Any crystal plane will reflect if the corresponding reciprocal lattice point lies on the surface of this sphere.

Excess zinc – It is the extra amounts of zinc which can accumulate on the steel because of chemical composition of the steel or the profile of the steel.

Exchange current – When an electrode reaches dynamic equilibrium in a solution, the rate of anodic dissolution balances the rate of cathodic plating. The rate at which either positive or negative charges are entering or leaving the surface at this point is known as the exchange current.

Exchange current density – It is the rate of charge transfer per unit area when an electrode reaches dynamic equilibrium (at its reversible potential) in a solution. i.e., the rate of anodic charge transfer (oxidation) balances the rate of cathodic charge transfer (reduction).

Excitation index – It is the ratio of the intensities of two selected spectral lines of an element having widely different excitation energies. This ratio serves to indicate the level of excitation energy in the source.

Excitation potential (x-ray) – It is the applied potential on an x-ray tube needed to produce characteristic radiation from the target.

Excitation volume – It is the volume within the sample in which data signals originate.

Excrescence – It is a term used by some tribologists describing micro-extrusions on friction surfaces that lead to localized welding.

Exempt solvents – These are solvents which are not subject to air pollution legislation. Several alcohols, esters, some ketones, and mineral spirits are exempt. Aromatic and some ethylenic compounds are not exempt, and their use as solvents is hence subject to regulation.

Exfoliation – It is the corrosion which proceeds laterally from the sites of initiation along planes parallel to the surface, normally at grain boundaries, forming corrosion products which force metal away from the body of the material, giving rise to a layered appearance. It is normally associated with wrought aluminum alloys.

Exhaust gas – It is also sometimes called flue gas or stack gas. It is the gas which emanates from th furnace because of the combustion of a fuel in the furnace. It contains the reaction products of fuel and combustion air and residual substances such as particulate matter (dust), and oxides of sulphur, nitrogen, and carbon.

Exit burr – It is the burr formed on the surface at which the cutting tool or its teeth leaves the work-piece.

Exogenic deposits -These are ore deposits formed because of the exogenic processes. Ore deposits are grouped as exogenic if their origin is because of the surficial processes such as weathering or shallow sedimentation with little or no relation to tectonics.

Exogenic processes – These are the processes which operates over the surface and are responsible for the formation of ore deposits. These processes include sedimentary precipitation, residual concentration processes, supergene enrichment process and volcanic exhalative processes.

Exogenous inclusion – It is an inclusion which is derived from external causes. Slag, dross, entrapped mould materials, and refractories are examples of inclusions which are classified as exogenous. In majority of the cases, these inclusions are macroscopic or visible to the naked eye.

Exogenous variables – An exogenous variable in a statistical model refers to a variable whose value is determined by influences outside of the statistical model. An assumption of statistical modelling is that explanatory variables are exogenous. When explanatory variables are endogenous, problems arise when using these variables in statistical models.

Exotherm – It is the liberation or evolution of heat during the curing of a plastic product.

Exothermic – It is characterized by the liberation of heat.

Exothermic atmosphere – it is a gas mixture produced by the partial combustion of a hydrocarbon gas with air in an exothermic reaction. It is also known as exogas.

Exothermic brazing (EXB) – It is a highly specialized processes where braze filler metals are melted using exothermic reactions between two metals, a metal oxide and a metal or an inorganic non-metal. It a process which utilizes the heat produced in a solid-state chemical reaction to melt a conventional filler metal or to produce molten filler metal as a product of the reaction.

Exothermic compounds – These are those compounds which generate enough heat to melt conventional filler metals. These compounds have been developed for iron alloys, copper alloys, and refractory metals. Aluminum compounds which react and produce a heterogeneous filler metal can be used to join aluminum alloys.

Exothermic reaction – It is a reaction which liberates heat, such as the burning of fuel or when certain plastic resins are cured chemically.

Exothermic soldering (EXS) – It is a highly specialized processes where solder filler metals are melted using exothermic reactions between two metals, a metal oxide and a metal or an inorganic non-metal.

Exothermic welding – It is also known as exothermic bonding, thermite welding (TW), and thermit welding. It is a welding process which uses molten metal to permanently join the conductors. The process employs an exothermic reaction of a thermite composition to heat the metal, and needfs no external source of heat or current.

Expanding – It is a process used to increase the diameter of a cup, shell, or tube.

Expanding gate valve – It is a gate valve comprised of a separate gate and segment which, as the valve operates the gate and segment, move without touching the seats, permitting the valve to be opened and closed without wear. In the closed position, the gate and segment are forced against the seats. Continued downward movement of the gate causes the gate and segment to expand against the seats. When the valve reaches its full-open position, the gate and segment seal off against the seats while the flow is isolated from the valve body.

Expansion, thermal – It is the tendency of matter to increase in length, area, or volume, changing its size and density, in response to an increase in temperature (normally it excludes phase transitions).

Expansive cements – These are hydraulic cements which expand slightly during the early hardening period after setting.  Expansive cement contains portland cement, anhydrous tetra-calcium-tri-alumino-sulphate, calcium sulphate, and uncombined calcium oxide (lime). Expansive cement is used to make shrinkage-compensating concrete which is used (i) to compensate for volume decrease due to drying shrinkage, (ii) to induce tensile stress in reinforcement, and (iii) to stabilize long term dimensions of post tensioned concrete structures. One of the major advantages of using expansive cement is in the control and reduction of drying shrinkage cracks.

Expendable pattern (mould) – It is a pattern which is destroyed in making a casting. It is normally made of wax (investment casting) or expanded polystyrene (lost foam casting).

Expendable-pattern (mould) casting (lost foam process) – The pattern used in this process is made from polystyrene (a light, white packaging material). Polystyrene foam is 95 % air bubbles, and the material itself evaporates when the liquid metal is poured on it. The pattern is made by moulding. The polystyrene beads and pentane are put inside an aluminum mould, and heated. It expands to fill the mould, and takes the shape of the cavity. The pattern is removed, and used for the casting process.

Expert system – It is a computer-based system which captures the knowledge of experts through the integration of databases and knowledge bases using search and logic deduction algorithms.

Explanatory data analysis – This analyzing method is used to determine the consequences happening to one variable when changing another one using randomized trial data sets.

Exploded assembly drawing – It shows exploded axonometric views. In the exploded views, the parts are positioned in the sequence of assembly, but separated from each other. Drawings of this type can be easily understood even by those with lesser experience in the reading of drawings, since in these exploded views, the parts are positioned in the sequence of assembly, but separated from each other.

Exploded views – These are typically used in assembly drawings in order to show the relationship or order of assembly of the different parts. An exploded view shows the components of an object slightly separated by distance, or suspended in surrounding space in the case of a three-dimensional exploded diagram.

Exploration – It consists on prospecting, sampling, mapping, diamond drilling and other work involved in searching for ore. It is a term embracing geophysics, geochemistry, and finally the more costly activities namely drilling into the ground for getting samples from any depth.

Exploratory data analysis – This analyzing method is used to explore the unknown relationships and discover new connections, and define future studies or questions.

Explosion protection – It is used to protect all sorts of buildings and civil engineering infrastructure against internal and external explosions or deflagrations.

Explosion welding – It is a solid-state welding process which produces coalescence by a controlled detonation, which causes the parts to move together at high velocity. The resulting bond zone has a characteristic wavy appearance.

Explosive compacting – It is the compacting of a powder at a very rapid rate by the use of explosives in a closed die.

Explosive forming – It is the shaping of metal parts in which the forming pressure is generated by an explosive charge which takes the place of the punch in conventional forming.

Exponential function – It is a mathematical function denoted by 𝑓(𝑥)=exp⁡(𝑥) f(x) = exp(x) or ‘e’ to the power ‘x’, (where the argument ‘x’ is written as an exponent). Unless otherwise specified, the term generally refers to the positive-valued function of a real variable, although it can be extended to the complex numbers or generalized to other mathematical objects like matrices.

Exposure – It is the exposure of an organism to a source of radiation characterized by the dose received. External exposure is the exposure from a radiation source located outside the organism, while the internal exposure is the exposure from a radiation source located inside the organism.

Exposure index – It is the relative transmittance or optical density of a selected spectral line, this value serving to indicate the degree of blackening of the photographic emulsion.

Extend – It means adding fillers or low-cost materials in an economy-producing endeavour. It is the adding of inert materials for improving void-filling characteristics and reduce crazing.

Extended x-ray absorption fine structure (EXAFS) – It is the weak oscillatory structure extending for several hundred electron volts away from an absorption edge. The oscillations occur since the electro-magnetic wave produced by the ionization of the absorbing atom for some energy ‘E’ has a wavelength Lambda= 1.225/(E-Ek)to the power 1/2 nanometer, where ‘Ek’ is the energy of the absorption edge. For example, a loss of 100 eV (electron volt) above an edge corresponds to a wavelength of 0.12 nanometer, which is of the order of atomic spacing. Consequently, the wave can be diffracted from neighboring atoms and return to interfere with the outgoing wave. An analysis of EXAFS data reveals important information about atomic arrangements and bonding. Either synchrotron x-radiation or the electron beam in the analytical transmission electron microscope can be used as the excitation source.

Extenders– These are low-cost materials which are used to dilute or extend high-cost resins without extensive lessening of properties.

Extensibility – It is the ability of a material to extend or elongate upon application of sufficient force, expressed as percent of the original length.

Extensional-bending coupling – It is a property of certain classes of laminates which show bending curvatures when subjected to extensional loading.

Extensional-shear coupling – It is a property of certain classes of laminates which show shear strains when subjected to extensional loading.

Extension bonnet – It is a bonnet with higher dimension between the packing box and bonnet flange for direction hot or cold service.

Extension stem – It is the equipment applied to the buried valves to provide above grade accessibility to operating gear, blowdown, and seat sealant systems.

Extensometer – It is an instrument for measuring changes in length over a given gauge length caused by application or removal of a force. It is normally used in tension testing. It is a mechanical or optical device for measuring linear strain due to mechanical stress.

External circuit – It consists of wires, connectors, measuring devices, and current sources etc., which are used to bring about or measure the desired electrical conditions within the test cell. It is this portion of the cell through which electrons travel.

External tooth gear – It is the most common type of spur gear. It has teeth cut on the outside perimeter of mating cylindrical wheels, with the larger wheel called the gear and the smaller wheel the pinion.

External venting – These are the holes which prevent high-pressure gas build-up in enclosed fabrications dipped in the molten zinc of the galvanizing bath.

Externally pressurized seal – it is a seal which operates on a thin film at the interface with the mating surface. The film is formed by high-pressure fluid which is brought to the interface at some mid-dam location and that is at a pressure equal to, or higher than, the up-stream seal pressure.

Extinction coefficient – It is the ratio of the diffracted beam intensity when extinction is present to the diffracted beam intensity when extinction is absent. It applies to primary or secondary extinction.

Extinction – It is a decrease in the intensity of the diffracted beam caused by perfection or near perfection of crystal structure.

Extraction – It is a general term denoting chemical methods of isolating phases from the metal matrix. It is also extraction of ore from ore deposit. Ore is extracted from the earth through mining and treated or refined, often through smelting, to extract the valuable metals or minerals.

Extractive distillation column – In this column the separation of non-aromatics contained in the feed is carried out, which is not possible under normal distillation conditions. The non-aromatics originally with boiling points higher than aromatics, are converted into low boiling non-aromatics which can be withdrawn at the top of the column while the aromatic substances dissolve in the N-formylmoropholine (NFM) is yielded at the bottom of the column.

Extractive distillation unit – In this unit, the BTXS (benzene, pure toluene, xylene, and solvent oil) raffinate is processed to separate benzene, toluene, xylene, and solvent. Further benzene and toluene are also separated. N-formylmoropholine (NFM) is used as solvent for the separation of BTX into BT (benzene and toluene) and X (xylene). Non aromatic compounds present in BTXS are removed by pressure distillation as solvent which is recovered in solvent recovery column. Benzene and toluene are separated in BT separation column. The objective of the extractive unit is to separate non aromatics from benzene and toluene. This unit produces pure benzene, pure toluene, xylene, and light solvent oil along with still bottom oil from BTXS raffinate.

Extractive metallurgy – It is the branch of process metallurgy dealing with the winning of metals from their ores.

Extra deep drawing steel – It is a superior quality of low carbon deep drawing steel.

Extra hard -It is a temper of non-ferrous alloys and some ferrous alloys characterized by values of tensile strength and hardness about one-third of the way from those of full hard to those of extra spring temper.

Extra spring – It is a temper of non-ferrous alloys and some ferrous alloys corresponding approximately to a cold-worked state above full hard beyond which further cold work does not measurably increase strength or hardness.

Extreme pressure (EP) additives – These are additives for lubricants with a role to decrease wear of the parts of the gears exposed to very high pressures. These additives are usually used under heavier loads, at high temperatures and low speeds to prevent catastrophic failure or seizing of the application. Common examples of extreme pressure additives are molybdenum disulfide, graphite, sulphurized olefins and di-alkyl-di-thiocarbamate complexes. extreme pressure additives are also added to cutting fluids for machining of metals.

Extreme-pressure (EP) lubricant – It is a lubricant which imparts increased load-carrying capacity to rubbing surfaces under severe operating conditions. Extreme-pressure lubricants normally contain sulphur, halogens, or phosphorus. The term anti-scuffing lubricant has been suggested as a replacement for extreme-pressure lubricant.

Extreme-pressure lubrication – It is a condition of lubrication in which the friction and wear between two surfaces in relative motion depend upon the reaction of the lubricant with a rubbing surface at elevated temperature.

Extruded hole – It is a hole formed by a punch which first cleanly cuts a hole and then is pushed farther through to form a flange with an enlargement of the original hole.

Extrusion – It is the conversion of an ingot or billet into lengths of uniform cross section by forcing metal to flow plastically through a die orifice. In forward (direct) extrusion, the die and ram are at opposite ends of the extrusion stock, and the product and ram travel in the same direction. Also, there is relative motion between the extrusion stock and the die. In backward (indirect) extrusion, the die is at the ram end of the stock and the product travels in the direction opposite that of the ram, either around the ram (as in the impact extrusion of cylinders such as cases for dry cell batteries) or up through the centre of a hollow ram.

Extrusion billet – It is a metal slug used as extrusion stock.

Extrusion butt end defect – It is a longitudinal discontinuity in the extreme rear portion of an extruded product, which is normally discarded.

Extrusion (ceramics) – It is the process of forcing a mixture of plastic binder and ceramic powder through the opening(s) of a die at relatively high pressure. The material can hence be compacted and emerges in elongated cylindrical or ribbon (or wire, etc.) form having the cross section of the die opening. The process is normally followed by drying, curing, activating, or firing.

Extrusion coating – It is using a resin to coat a substrate by extruding a thin film of molten resin and pressing it onto or into the substrate, or both, without the use of an adhesive.

Extrusion defect – The preferred term is extrusion pipe which is a central oxide-lined discontinuity which occasionally occurs in the last 10 % to 20 % of an extruded metal bar. It is caused by the oxidized outer surface of the billet flowing around the end of the billet and into the centre of the bar during the final stages of extrusion.

Extrusion, direct – Ij it a stem, normally with a pressure pad in front, pushes the billet in a stationary container through a tool of the desired shape, the die. Relative movement takes place between the billet and the container.

Extrusion forging – It is the forcing metal into or through a die opening by restricting flow in other directions. It is also a part made by the operation.

Extrusion, indirect – In it, the die is located in front of a hollow stem and pushed against the billet by the forward movement of the container closed at the back. There is, hence, no relative movement between the billet and the container.

Extrusion ingot – It is a cast metal slug used as extrusion stock.

Extrusion log – It is the starting stock for extrusion billet. Extrusion log is normally produced in lengths from which shorter extrusion billets are cut.

Extrusion (metals) – It is the conversion of an ingot or billet into long lengths by forcing metal to flow through a die orifice. The cross section of the extrusion can be circular or highly irregular and specific in shape.

Extrusion pipe – It is a central oxide-lined discontinuity which occasionally occurs in the last 10 % to 20 % of an extruded metal bar. It is caused by the oxidized outer surface of the billet flowing around the end of the billet and into the centre of the bar during the final stages of extrusion. It is also called coring.

Extrusion (plastics) – It consists of compacting a plastic material into a powder or granules in a uniform melt and forcing it through an orifice in a more or less continuous fashion to yield a desired shape. While held in the desired shape, the melt is required to be cooled to a solid state.

Extrusion process – Extrusion is a compressive deformation process in which a block of metal is squeezed through an orifice or die opening in order to get a reduction in diameter and increase in length of the metal block. The resultant product has the desired cross-section. Extrusion involves forming of axi-symmetric (symmetrical about an axis) products. Dies of circular on non-circular cross-section are used for extrusion. Extrusion normally involves high forming forces. Large hydrostatic stress in extrusion helps in the process by improving the ductility of the material. Metals like aluminum, which are easily workable, can be extruded at room temperature. Other difficult to work metals are normally hot extruded or warm extruded. Both circular and non-circular products can be achieved by extrusion. Channels, angles, rods, window frames, door frames, pipes tubes, and aluminum fins are some of the extruded products. Difficult to form materials such as steels, nickel alloys are extruded because of inherent advantage of the extrusion process, such as, no surface cracking because of reaction between the billet and the extrusion container takes place. Extrusion results in better grain structure, better accuracy, and surface finish of the components. Less wastage of material in extrusion is another attractive feature of the extrusion process.

Extrusion seam – It is a region in extruded hollow profiles observed after creating two streams of metal and rejoining them around the mandrel of a porthole or bridge die.

Extrusion stock – It is a rod, bar, or other section which is used to make extrusions.

Extrusion tooling – It can be broadly classified into (i) tooling which is directly involved in the shape forming of the material being extruded, (ii) tooling which is not directly involved, and (iii) tooling which fulfills auxiliary and support functions. The first group includes extrusion dies, porthole and bridge dies, as well as mandrels. These extrusion tools come into direct contact with the billet material heated to the deformation temperature. The second group includes extrusion tooling which does not have any shape-producing function but, at the same time, is indirectly involved in the shape-changing process. This includes container liners, extrusion stems, dummy blocks, and mandrel holders as well as die-carrying stems, container-sealing plates, and container-sealing stems with sealing discs in indirect extrusion. The third group is represented by the auxiliary tooling, including die holders, tool holders, pressure plate holders, as well as support tooling including the container mantle, liner holder, and sub-bolsters and bolsters in the direct-extrusion tool stack.

Exudation – it is the action by which all or a portion of low melting constituent of a compact is forced to the surface during sintering. It is sometimes referred to as bleed out or sweating.

Ex Works – ‘Ex Works’ means that the seller delivers when it places the goods at the disposal of the buyer at the seller’s premises or at another named place (i.e. works, factory, warehouse, etc.). The seller does not need to load the goods on any collecting vehicle, nor does it need to clear the goods for export, where such clearance is applicable.

Eyehole – It is the region in which film is absent because of the non-wetting of the metal surface by the coating.

Eyelets – They are intended to be placed on the load either by threading or by welding for lifting it

Eyeleting – It is the displacing of material about an opening in sheet or plate so that a lip protruding above the surface is formed.

Eye-piece – It is a lens or system of lenses for increasing magnification in a microscope by magnifying the image formed by the objective.