The insulation/coatings for wires and cables are typically mixed with two or more components at the intake of a single or twin screw extruder. The insulation or coating material is applied via a crosshead die. In this way the cable core or cable is fed through a special pipe. The polymer is entered on the side of this pipe and covers the cable core in a distribution area.

After extrusion, the insulated wire or coated cable is cooled by air, sprayed water or a water bath and is then sent to a haul-off and cutting station before being wound up.

For multilayer coatings, e.g. for the manufacture of coaxial cables, a multistage process must be used. First the cable core must be insulated, cooled and then sent to a special coiling station where the grounding and shielding is plaited around the insulation. The product will be coated with flexible and permanent insulation in another extrusion step.

When there is no need for an intermediary step, i.e. plaiting ground wires around coaxial cables, multiple layers can be co-extruded simultaneously. Colour code strips for electrical wiring can be produced by using a special instrument during co-extrusion.