Screws and barrels are like screws and nuts and are a combination of parts that are inseparable. The perfect meshing and just the right gap between them makes the material plasticization, product quality and production efficiency significantly improved. However, the sharp knife can’t stand the polishing of time. When the two parts wear each other seriously, it will seriously affect the output of the extruder. Then it is especially important to rebuild this pair of CPs!
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 wear gradually. The diameter of the screw is gradually reduced, and the diameter of the inner hole of the barrel is gradually increased. Thus, the matching diameter gap between the screw and the barrel increases little with the gradual wear of the two. However, since the resistance of the front head and the splitter plate of the barrel is not changed, this increases the leakage flow when the extruded material advances, that is, the amount of material flowing from the diameter gap to the feed direction increases. As a result, the extruder production is reduced. This phenomenon causes the residence time of the material in the barrel to increase, causing the material to decompose. In the case of polyethylene, the hydrogen chloride gas produced by the decomposition enhances the corrosion of the screw and the barrel.