According to the screw structure and the geometry of the threaded part, the screw can be divided into a common type screw, a new type screw and a vent type screw.

1 Ordinary type screw A most widely used and most common type of screw, widely used in various types of extruders. According to the pitch and the depth of the thread on the screw, it can be divided into the screw with the same thread pitch and the different depth of the thread groove. The thread pitch is not equal and the thread groove depth is equal and the screw pitch and the thread groove depth are not equal.

2 The new screw is different from the ordinary screw in that it has some non-threaded components in the threaded part of the screw, such as adding some round pins or adding a thread different from the original thread pitch to improve the plastic. Mixing and plasticizing effects, improve the quality of melt plasticization of materials, shorten extrusion time and increase production.

3 Vent-type screw A special type of screw specially designed to smoothly remove air, volatile gas and water vapor in the material to be extruded.