Causes Of Wear Of Threaded Rods

1. Each plastic has an ideal plasticizing processing temperature range, and the barrel processing temperature should be controlled to be close to this temperature range. Granular plastics enter the barrel from the hopper and first reach the feeding section. Dry friction will inevitably occur in the feeding section. When these plastics are not heated enough and melt unevenly, it is easy to cause increased wear on the inner wall of the barrel and the surface of the screw. Similarly, in the compression section and homogenization section, if the melting state of the plastic is disordered and uneven, it will also cause increased wear.
2. The speed should be properly adjusted. Because some plastics are added with reinforcing agents, such as glass fiber, minerals or other fillers. The friction of these substances on metal materials is often much greater than that of molten plastics. When these plastics are injected, if a high speed is used, while increasing the shear force on the plastic, the reinforcement will also produce more torn fibers accordingly. The torn fibers contain sharp ends, which greatly increase the wear force. When inorganic minerals slide on the metal surface at high speed, their scraping effect is also not small. Therefore, the speed should not be adjusted too high.
3. The screw rotates in the barrel, and the friction between the material and the two causes the working surfaces of the screw and the barrel to gradually wear: the screw diameter gradually decreases, and the inner diameter of the barrel gradually increases. In this way, the matching diameter gap between the screw and the barrel increases little by little as the two gradually wear. However, since the resistance of the head and the diverter plate in front of the barrel has not changed, this increases the leakage flow of the extruded material when it moves forward, that is, the flow of the material from the diameter gap to the feed direction increases. As a result, the production volume of plastic machinery decreases. This phenomenon also increases the residence time of the material in the barrel, causing the material to decompose. If it is polyvinyl chloride, the hydrogen chloride gas produced by the decomposition strengthens the corrosion of the screw and the barrel.
4. If there are fillers such as calcium carbonate and glass fiber in the material, it can accelerate the wear of the screw and the barrel.
5. Because the material is not plasticized evenly, or metal foreign matter is mixed into the material, the torque of the screw rotation suddenly increases. This torque exceeds the strength limit of the screw and causes the screw to break. This is an unconventional accident damage.