4. Different types of heads and dies

4.1 Function of the extrusion head

The plastic emerges from the extruder in the form of a strand. An extrusion die is required to shape this material into a tube that is applied around a conductor (to insulate a wire) or a bundle of wires (to sheathe it).

Conventional tube extrusion is performed along the axis of the screw. This is not possible in cable manufacturing, because the tube must be extruded along the axis of the cable core (wire or bundle of wires), which is oriented perpendicular to the extruder’s axis. In fact, a die head with a tube axis parallel to the screw would prevent the conductor from passing through. This function is provided by the connection between the extrusion head and the die.