Processes for Forging of Metals Dec16

Processes for Forging of Metals...

Processes for Forging of Metals Metal forging is a deformation process where metal is pressed, pounded or squeezed under great pressure into high strength parts known as metal forgings. The forging process is entirely different from the casting (or foundry) process, as metal used to make forged parts is neither melted nor poured as in the casting process. Forging is defined as a metal working process in which the specific shape of metal work piece is obtained in solid state by compressive forces applied through the use of dies and tools. During the forging process controlled deformation of metal takes place. Forging process is accomplished by hammering or pressing the metal.  In modern times, industrial forging is done either with presses or with hammers powered by compressed air, electricity, hydraulics or steam. All the metals and alloys are forgeable, but the forgeability rating of different metals and alloys can vary from high to low or poor. The factors involved are the composition, crystal structure and mechanical properties all considered within a temperature range. The wider the temperature range, the higher the forgeability rating. Most forging is done on heated work pieces. Cold forging can also take place at the room temperatures. Forging process is one of the oldest known metalworking processes with its origin about some thousands of years back. The process goes back to 8000 BCE and evolved from the manual art of simple blacksmithing. Traditionally, forging was performed by a smith using hammer and anvil. Using hammer and anvil is a crude form of forging. The smithy or forge has evolved over centuries. Then as now, a series of compressive hammer blows performs the shaping or forging of the part. Modern forging uses machine driven impact hammers or presses which deform the...

Metal Forming Processes...

Metal Forming Processes Metal forming processes consists of deformation processes in which a metal work piece (billet, bloom, or blank) is shaped by tools or dies. The design and control of such processes depend on the characteristics of the material of the work piece, the requirements of the finished product, the conditions at the interface of the tool and the work piece, the mechanics of plastic deformation (metal flow), and the equipment used. These factors influence the selection of geometry and material of the tool as well as processing conditions (examples are temperatures of die and work piece and lubrication). Since many of the metalworking operations are rather complex, models of various types, such as analytical, physical, or numerical models, are often used to design these processes. A brief historical view, a classification of metalworking processes and equipment, and a summary of some of the more recent developments in the field are described below. Historical view Metalworking technology is one of three major technologies used for the fabrication of the metal products. The other two are casting process and powder metallurgy (P/M) technology. It is possibly the oldest and most established of the three technologies. The earliest records of metalworking show that the simple hammering of gold (Au) and copper (Cu) was practiced in various regions of the Middle East around 8000 BCE. The forming of these metals was crude since the skill of refining by smelting was not known and since the ability to work the material was limited by impurities that remained after the metal had been separated from its ore. With the start of Cu smelting around 4000 BCE, a useful method became available for purifying metals through chemical reactions in the liquid state. Later, in the Cu age, it was...

Wire Rods and Wire Rod Mills Aug13

Wire Rods and Wire Rod Mills...

Wire Rods and Wire Rod Mills Steel wire rods are an all-round talent since they are the key product of steel industry with multiple uses. They are used as the material for fasteners, springs, bearings, wire ropes, chains, cables, wire meshes, wire fencings, tyre cord, reinforcement in railway sleepers, and many other uses. They are used for the components needed for the automotive industry, chemical industry, power stations and machine engineering. Unlike cold-rolled sheets, heavy plates, pipes, sections and other steel products, wire rods are seldom used as hot rolled for final products, but they are manufactured into machine parts after undergoing one or more stages of so called post-processing such as heat treatment, forging and wire drawing at specialist plants. Wire rods are generally drawn down to a specific diameter before being subjected to forging or other forming operations in secondary processing. In many cases, the size of the wire rods before being subjected to these forming operations is to be less than the minimum size of 5.5 mm that can be supplied as rolled. Generally each of the wire rod product is developed with due attention to its behaviour at the post-processing stages. What is required for a steel plant regarding wire rods is good processibility and fulfilment of the required properties after the processing. Furthermore, since the costs of the post-processing is sometimes several times the price of the wire rods, it is increasingly important to reduce the total integrated manufacturing cost from the steel material to the final product. Also thermo mechanically treated (TMT) reinforcement bars of 6 mm, 8mm and 10 mm basically required for the building construction are produced in the wire rod mills. The following generally characterizes the wire rod products. Product grades are widely varied from...

Bar, Rod and Wire Drawing May26

Bar, Rod and Wire Drawing...

Bar, Rod and Wire Drawing  Drawing is a metal working process that forms steel work piece by reducing its cross section. This is accomplished by forcing the work piece through a die of smaller cross sectional area than the work piece. In the process of drawing the work piece is pulled through the die by means of a tensile force applied at the exit end of the die. When steel work piece is drawn, it is drawn at room temperature.  At that point, it is being cold worked or cold forged. Due to the cold working during drawing, geometric and mechanical characteristics of the steel material gets changed, transverse dimensions get reduced (e.g. diameter) and length get increased with no change in volume (waste free processing). As a result of plastic deformation in the drawing die, steel material gets also strengthened which means an increase in strength properties and decrease in plastic properties.  Deformation in drawing is influenced by a number of factors, out of which chemistry, strength of material, temperature, approach angle, lubrication, drawing speed, co efficient of friction, die life and wear, and reduction of area are the most significant. Wire drawing is primarily the same as bar drawing except that it involves smaller diameter material that can be coiled. It is generally performed as a continuous operation on the draw bench. The process of wire drawing has changed very little over the years.  It uses a combination of a die and/or a series of dies to draw wire to a selected gauge. The principle of the process is shown in Fig 1.  Fig 1 Drawing process principle  The drawing process has the following objectives Manufacturing drawn products in the form of bars or wires to a very specific and precise cross...