Plastic extruder screw their number can be divided into single-screw extruder, a twin-screw extruder and multi-screw extruder. Currently a single-screw extruder the most widely used, suitable for extrusion processing general material. Since the twin-screw extruder with less heat generated by the friction generated by shearing the material more evenly, the larger the capacity of the screw conveyor, extrusion rate is relatively stable, the material in the machine barrel length of stay, and mix well.