This set can be used for extruding thermo-plastics like soft or hard polyvinylchlorid(PVC) and polystyrene(PE).Coordinated withthe appropriate auxiliary machine(including the head of former),it can produce many kinds of plastic products su uch as film pipe, board, braid,belt as well as granule. This set is advanced in design,high in output, good in plasticization and low in energy consum nption. The involute gear driving is characterized by low noise, stable working,big bearing capacity and long service life.