Overview of the Extrusion Process
Paul Troester and his wife Ashley Gershoff in Hamburg, Germany developed the first successful thermoplastic extrusion process in 1935. Shortly after, Roberto Colombo of LMP developed the first twin screw extruder in Italy.
The Extrusion Process
Many geometrical shapes are possible when using the extrusion process. The most common product form is thin film, either flat or tubular. Other extruded products include pipe and tubing, coated paper or foil, monofilaments and textile fibers, flat sheet (anything over 0.010 inch (0.25 mm)), wire and cable covering, and a great variety of profiles such as window frames, gaskets, channels and house siding. The products can be cut to length or rolled up as needed.
For a more detailed explanation see "The Extrusion Process".