ABSTRACT

Tooling design is a subject worthy of an entire text by itself. However, because of the prefaced need, an introduction to some of the process-tooling requirements is included here.

A single-screw extruder is shown in Figure 9.1. Granules of a polymer are fed into the feed hopper. These granules become compacted, forwarded, heated, and mixed. (The study of the flow of the molten polymer through the extruder is a subject of research in graduate-level fluid mechanics. The flow is that of a nonNewtonian viscous fluid. One must be concerned with thermomechanical coupling in the equation of state.) The molten polymer is forced through a die, after which the polymer cools and solidifies, as shown in Figure 9.2. The polymer expands radially and shrinks longitudinally. The die designer must be concerned with these thermal changes in dimensions.