How can the wear of screw barrels be reduced and their usage improved

The screw barrel of an injection molding machine operates for a long time under high pressure, high temperature, high mechanical torque and high friction conditions. The first few factors are required by the process conditions, but the wear and tear caused by friction is inevitable. Generally, screws undergo surface nitriding treatment to enhance surface hardness, that is, to improve wear resistance. However, if the causes of wear are ignored and efforts are not made to minimize the wear as much as possible, the working life of the screw will inevitably be greatly reduced. The following two points will introduce the causes of screw wear and the methods to reduce it: 1. Each plastic raw material has an ideal processing temperature range for plasticizing, so the processing temperature of the barrel 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 is bound to occur in the feeding section. When these plastics are insufficiently heated and unevenly melted, it is very likely 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 molten state of the plastic is disordered and uneven, it will also cause increased wear. 2. The rotational speed should be properly adjusted. Because some plastics are added with reinforcing agents, such as glass fibers, minerals or other fillers. The frictional force of these substances against metallic materials is often much greater than that of molten plastics. When injection molding these plastics, if a high rotational speed is used, while increasing the shear force on the plastic, it will also cause the reinforcement to produce more shredded fibers. The shredded fibers contain sharp ends, which greatly increases the wear force. When inorganic minerals slide at high speed on the surface of metals, their scraping effect is also considerable. So the rotational speed should not be set too high.