Page 84 - Module DMV20173

4.0 BULK DEFORMATION PROCESSES

8. Die wear can be excessive.
9. Cooling of the surface of the hot billet and die can result in highly non-uniform

deformation.
10. To reduce cooling of the billet and to prolong die life, extrusion die maybe preheated.
11. Figure 4.19 shows some of the hot extrusion products.

4.4.6 COLD EXTRUSION

1. General term that often denoted a combination of operations such as direct and
indirect extrusion and forging.
2. The process done at room temperature or slightly elevated temperatures.

3. Process can be used for most materials-subject to designing robust enough tooling
that can with stand the stresses created by extrusion
4. Cold extrusion process is done below the re-crystallization temperature of the

material used.
5. This process is typically used to make parts with hollow cross-sections as shown in

Figure 4.20.
6. Used widely for components in automobiles, motorcycles, bicycles.
7. Examples of the metals that can be extruded are lead, tin, aluminum alloys, copper,

titanium, molybdenum, vanadium, and steel.
8. Figure 4.21 shows example of cold extrusion.

Figure 4.20 Some components produced by cold extrusion.

BPLK 116 DMV 20173