Page 77 - Module DMV20173

4.0 BULK DEFORMATION PROCESSES

Example 4.2
Briefly explain, why is control of the volume of the blank important in closed-die

forging.

Solution:

1. Accurate control of the blank volume and proper die design are essential in order
to produce a forging with desired dimensional tolerance.

2. Undersized blanks produce uncompleted filling of the die cavity.
3. Oversized blanks generate excessive pressures and may cause die fail.

EXERCISE 4.2

In impression-die forging, during deformation, some of the material flows
outward and forms a flash. Explain the functions of flash in impression-die
forging.

4.4 EXTRUSION OF METALS

1. Extrusion is the process by which a block of metal is reduced in cross section by
forcing it through a die orifice under high pressure (Figure 5.12).

2. Extrusions have numerous applications in the manufacture of continuous as well
as discrete products from a wide variety of metals and alloys.
th
3. Metal extrusion was developed in the late 18 century for making lead pipe. The
basic process of forcing a round billet through a shaped die is still used today.
4. Modern variants can produce clad products in one go - e.g. copper clad with

silver.
5. In the extrusion process, the material is forced through a deforming die.
6. Drawing is related to extrusion but is used for smaller (round) where the cross-

section of solid rod, wire, or tubing is reduced or changed in shape by pulling it
through the die rather than pushing.

BPLK 109 DMV 20173