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Common causes of damage screw and barrel for extruder

Update:19 Oct 2018
Summary:

1. The screw of the extruder rotates in the barrel, and […]

1. The screw of the extruder rotates in the barrel, and the friction between the material and the two causes the working surface of the extruder screw and the barrel to wear gradually: the diameter of the screw of the extruder is gradually reduced, and the diameter of the inner hole of the barrel is gradually increased. . Thus, the matching diameter gap between the extruder 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 extruder 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 of the extruder.
3. Since the material is not plasticized evenly, or metal foreign matter is mixed into the material, the torque of the extruder screw is suddenly increased. This torque exceeds the strength limit of the extruder screw, and the extruder screw is broken. This is an unconventional accident damage.