During extrusion, the extruder melts PVC granulate and presses it. The extruder then injects the resulting mass through the extruder head, e.g. onto strands or wire ropes. This creates the sheath of the cable. Extrusion is a complex part of cable production in which material, pressure, temperature and external conditions must be perfectly matched to each other in order to produce a faultless cable. A distinction is made between pressure extrusion and hose extrusion.