Difference between screw of injection molding machine and screw of extruder

（1） The ratio of the length L to the diameter D of the screw and the compression ratio of the screw used in the injection molding machine are slightly smaller than that of the screw used in the extruder.

（2） The depth of the thread groove in the metering section of the injection molding machine is slightly larger than that of the screw in the metering section of the extruder.

（3） The feeding section of injection molding machine is slightly longer than that of extruder screw. The length of plasticizing section is shorter than that of extruder screw.

（4） The head structure of injection molding machine is mostly cone-shaped, and it also has check valve.

The gradual change screw of injection molding machine is mostly used for injection molding of non crystalline plastics (such as PVC). The mutant screw in injection molding machine is mainly used for injection molding of crystalline plastics (such as polyolefin and polyamide).

Precautions for screw control

Rotation speed of screw: the determination of extrusion working speed is closely related to the specification of extruded pipe. Too high rotation speed and too fast extrusion of raw materials will produce high friction heat, which will make the inner wall of the pipe rough. So we must consider all factors.

Cooling of screw: cooling and cooling can prevent the material from decomposing casually due to the excessive friction heat and high temperature rise of raw materials. It can also reduce the coarseness of the pipe surface. Your words will affect the plasticization of raw materials, increase the resistance of material flow, and reduce the production of products. The temperature return water is controlled between 50 and 80 degrees.