Extrusion is widely used for continuous production of film, sheet, tube, and other profiles; also used in conjunction with blow molding. Thermoplastic or thermoset molding compound is fed from a hopper to a screw and barrel where it is heated to plasticity then forwarded, usually via a rotating screw, through a nozzle possessing the desired cross section. Production lines require input and takeoff equipment that can be complex. Low tool cost, numerous complex profile shapes possible, very rapid production rates, can apply coatings or jacketing to core materials (such as wire).

One version of this process is to form a crosslinked insulation on wire. Like the thermoset injection molding process, the extruder ony heats the material up moderately so the crosslinking reaction will not start too early. The extruder coats the wire and it then enters a steam tube refered to as a continuous vulcanization chamber or CV. This steam is the catalyst that kicks over the reaction that crosslinks the material. The length of the tube must allow for sufficient exposure to complete the reaction. There are two associated processes used for producing the same product. Wire can be covered conventionally like thermoplastic extrusion onto the conductor and then sent through an electron beam unit that irradiates the insulation. The electron beam unit creates the energy that starts and completes the crosslinking of the wire insulation. By an alternate chemistry, irradiation is not necessary. Moisture comes in contat with the wire insulation and creates the catalyst that start crosslinking. Many times this is accelerated by placing the wire in an autoclave for a short period of time.