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Close Die Forging

In closed or impression die forging, the starting forging stock is invariably a billet or bloom, since the weight and dimensions are usually critically. Upper and lower dies are contoured or sunk to form the required shape when the billet is inserted between them. The forging force may be supplied instantaneously, when the dies are closed over the billet, or more gradually when a hydraulic press is used. High forging pressures are required to make the material flow to fill the dies, and for even modestly sized forging such as automotive crankshafts, hydraulic or large mechanical presses are used. Since appreciable costs are involved in providing the dies, close die forging is more applicable to large production runs.(Edward G. Nisbett, Steel Forgings: Design, Production, Selection, Testing, and Application,

ASTM International,2009,p,25 )

Compound Die

In a compound die, as distinct from the progressive die, all the necessary operations are

carried out at a single station, in a single stroke of a ram. To do more than one set of operations,

a compound die consists of the necessary sets of punches and dies. During the part of stroke,

piercing of holes is done in the stock and upon further travel, the blanking operation is done.

( P. N. Rao, Manufactoring Technology:Foundry, Forming and Welding,

The McGraw-Hill Publishing, 1998, p.327 )

Isothermal Annealing

Isothermal annealing is derived from the exact knowledge of temperature-time diagrams.

This type of annealing is useful for softening steels for the subsequent machining operations.

This treatment consist of austenitizing at the normal annealing temperature (full annealing)

and then cooling rapidly to the appropriate temperature below Ar1, usually about 50-60 C below

Ar1(isothermal holding in pearlite range). This temperature held for a predetermined time,

enabling the complete austenite decomposition to take place for producing a structure having

optimum machinability. After the transmition is complete, the steel is cooled in a furnace,

or air-cooled, or rapidly cooled. (K. H. Prabhudev, Handbook of Heat treatment of Steels,

McGraw-Hill Pub., 1988, p. 50)

Automatically Programmed Tool (APT)

APT uses English-like language statements to define part shape and tool motion as well as

machine tool dependent data, such as feed rates and spindle speeds. This data is contained in an

APT part program. An APT processor program is used to read these statements, interpret the

meaning, and perform all the necessary calculations in order to generate a series of cutter

location points that define the cutter path. The APT processors a computer program which

runs on a mainframe computer, possibly at a central site with time-sharing facilities. The

generalized APT output is converted to the particular format G-Code required by the CNC machine

using a postprocessor program.(A. Alavudeen, N.Venkateshwaran, Computer Integrated

Manufacturing ,Prentice-Hall Pub., 2008, p.198)