Abstract: The extrusion apparatus used to make a marbled section of a thermoplastic material is connectable to a screw press with at least one screw shaft and an extruder housing. A thermoplastic base material having one color is fed in using the screw press. A thermoplastic marbling material having another color is mixed with the thermoplastic base material. The extrusion apparatus includes an extrusion apparatus housing, a central passage for receiving the thermoplastic base material which encloses the screw shaft and a shaping outlet. The extrusion apparatus housing has at least one injector cavity in which an injection device for feeding in the thermoplastic marbling material is mounted.

Abstract: In the extrusion process an inhomogeneous thermoplastic marbled product is made from a base plastic material and at least one marbling additive material mixed therein. The additive material is fed into the interior of an extrudate flow made from the base plastic material in an extruder device. The extruder has a mixing head at the end of its screw having a narrow throat surrounded by a ring. The ring is formed with angularly spaced slot-like passages for the base material. The additive veining plastic is fed through the mixing head downstream of this throat.