In the extrusion process, plastic in the form of pellets or powder (dry-blends) are fed into a heated cylinder where rotating screws homogenize it and squeeze it through a die to give a finished or semi-finished product. Pellets are used in single screw extruders, and powders are used in twin screw extruders. The die is designed to produce the desired shape of the end product.

Extruding can produce soft or rigid items which can be compact or cellular in form (foaming process).

By the extrusion process with the proper dies we can produce pipes, tubes, insulated wires, films and sheets.