Causes of damage to the screw and barrel

1. The screw rotates in the barrel, and the friction between the material and the two causes the working surface of the screw and the barrel to gradually wear out, the diameter of the screw gradually decreases, and the diameter of the inner hole of the barrel gradually increases. In this way, the matching diameter gap between the screw and the barrel increases a little as the two gradually wear. However, because the resistance of the head and the splitter plate in front of the barrel has not changed, this increases the leakage flow of the extruded material when it advances, that is, the amount of material flowing from the diameter gap to the feeding direction increases. As a result, the output of the extruder decreased. This phenomenon increases the residence time of the material in the barrel and causes the material to decompose. If it is polyethylene, the hydrogen chloride gas produced by decomposition strengthens the corrosion of the screw and barrel

2. If there are fillers such as calcium carbonate and glass fiber in the material, it can accelerate the wear of the screw and barrel.

3. Because the material is not plasticized uniformly, or metal foreign matter is mixed into the material, the torque of the screw is suddenly increased. This torque exceeds the strength limit of the screw, causing the screw to twist and break. This is an unconventional accident damage.