Page 78 - Module DMV20173

4.0 BULK DEFORMATION PROCESSES

Figure 4.12 Extrusion process.

4.4.4 GENERAL ASPECTS OF EXTRUSION PROCESS

1. Process where a solid plastic (resin), in the form of pellets, is continuously fed to

a heated chamber and carried along by a feed-screw within.
2. The feed-screw is driven via drive/motor and tight speed and torque control is
critical to product quality.

3. As it is conveyed it is compressed, melted, and forced out of the chamber at a
steady rate through a die.

4. The immediate cooling of the melt results in re-solidification of that plastic into a
continually drawn piece whose cross section matches the die pattern.
5. This die has been engineered and machined to ensure that the melt flows in a

precise desired shape.
6. Figure 4.13 shows the example of machine for extrusion

7. Three basic types of extrusion:
 direct or forward extrusion;
 indirect extrusion;

 hydrostatics extrusion.

BPLK 110 DMV 20173