Screw difference between injection molding machine and extruder
（1） The ratio of L value to D value of screw diameter and compression ratio of thread used in injection molding machine are slightly smaller than those of screw used in extruder.
（2） The depth of thread groove in metering section of injection molding machine is slightly larger than that of screw used in extruder.
（3） The feeding section of the injection molding machine is slightly longer than that of the extruder screw. The length of plasticizing section is shorter than that of extruder screw.
（4） Most of the head structure of injection molding machine is pointed conical, and there is a check valve.

The gradual change screw of injection molding machine is mostly used for injection molding of non crystalline plastics (such as PVC). Mutation screw in injection molding machine is mostly used for injection molding of crystalline plastics (such as polyolefins and polyamides).
Precautions for screw control
Screw speed: the determination of the working speed of the extrusion is closely related to the size of the extruded pipe. If the rotational speed is too high and the material is extruded out too fast, the friction heat will be high and the inner wall of the pipe will be rough. Therefore, we must consider all factors.
Screw cooling: cooling and cooling can prevent excessive friction heat and high temperature rise of raw materials to form random decomposition. It can also reduce the roughness of 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 of return water should be controlled between 50 and 80 degrees.

Zhoushan Tianxiang Screw Manufacturing Factory