How to reduce the wear of the screw barrel
The screw barrel of the injection molding machine works for a long time under high pressure, high temperature, high mechanical torque and high friction environment. The first few factors are required for the process conditions, but the losses caused by friction are inevitable. Generally, the screws are subjected to surface nitriding treatment to increase the surface hardness, that is, to improve the wear resistance. However, if the cause of wear is neglected, and the failure to try to reduce the wear as much as possible will inevitably greatly reduce the working life of the screw.
Each plastic material has an ideal plasticizing processing temperature range, so the barrel processing temperature should be controlled to bring it close to this temperature range. When the granular plastic enters the barrel from the hopper, it will reach the feeding section first, and dry friction will inevitably appear in the feeding section. When these plastics are insufficiently heated and melted unevenly, it is easy to cause the inner wall of the cylinder and the surface of the screw to wear more. Similarly, In the compression section and the homogenization section, if the molten state of the plastic is disordered, the wear is also increased.
The speed should be adjusted properly. Because some plastics are supplemented with reinforcing agents such as fiberglass, minerals or other fillers. These materials tend to have a much greater frictional force on metallic materials than molten plastics. In the injection of these plastics, if the high speed is used, the shearing force on the plastic will be increased, and the reinforcement will also produce more shredded fibers correspondingly. The shredded fibers contain sharp ends and wear. The power is increasing. When the inorganic minerals slide at high speed on the metal surface, the scraping effect is not small. Therefore, the speed should not be adjusted too high.