ABSTRACT
The process of extrusion has been practiced for well over a century. It involves pushing an extrudate through an opening to produce a predefined shape. The extrusion mechanism can be a simple piston contained within a cylinder, which is capped with a shaping orifice referred to as the die. Material is loaded into the cylinder, the piston moves forward creating pressure at the die, and the material thus emerges in its shaped form from the die. This type of extrusion process is batch in nature because the piston must be retracted periodically to permit refilling of the chamber. Furthermore, the heat buildup in the extrudate is usually limited to the viscous energy dissipation in the die (Hauck and Huber, 1989). This process is considered to be a discontinuous or batchtype extrusion process.
