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...

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...