Extruders can be divided into single-screw, twin-screw and multi-screw extruders according to the number of screws. At present, single-screw extruders are more widely used and are suitable for extrusion processing of general materials. Due to the fact that the twin-screw extruder has less heat generated by friction, the shearing of the material is relatively uniform, the conveying capacity of the screw is large, the extrusion volume is relatively stable, the material stays in the barrel for a long time, and the mixing is uniform.
　　Single-screw machine and twin-screw machine: one is a screw and the other is two screws. Both are driven by a motor. The power varies from screw to screw. The power of 50 cone double is about 20kW, and the output of 65 cone is about 37kW. The output is related to the material and screw. The output of 50 cone double is about 100-150kg/h, and the output of 65 cone double is about 200-280kg/h. The output of a single screw is only half.
The main symbol of the development of 　　 single screw extruder lies in the development of its key part-screw. In recent years, people have conducted a lot of theoretical and experimental research on screws, and there have been nearly a hundred types of screws, the common ones are separation type, shear type, barrier type, split type and wave type.
　　From the perspective of single-screw development, although single-screw extruders are relatively complete, with the continuous development of polymer materials and plastic products, more characteristic new-type screws and special single-screw extruders will emerge. In general, the single-screw extruder is developing in the direction of high speed, high efficiency and specialization.
The twin-screw extruder has good feeding characteristics and is suitable for powder processing. It has better mixing, venting, reaction and self-cleaning functions than the single-screw extruder. It is characterized by processing and blending plastics with poor thermal stability. The material time shows its superiority.