The screw of vertical injection molding machine works under high temperature, high pressure, high mechanical torque and high friction environment for a long time. The first few factors are required by the process conditions, and the loss caused by friction is inevitable. Generally, the screw of the vertical injection molding machine has been subjected to surface nitriding treatment to improve the surface hardness, that is, to improve the wear resistance. However, if the cause of the wear of the vertical injection molding machine is neglected, and the wear of the vertical injection molding machine is not reduced as much as possible, the working life of the screw of the vertical injection molding machine will be greatly reduced.
The following describes the causes of vertical injection molding machine screw wear and methods to reduce wear
1. Each plastic has an ideal plasticizing processing temperature range, and the processing temperature of the vertical injection molding machine barrel should be controlled to be close to this temperature range. When the granular plastic enters the barrel of the vertical injection molding machine from the hopper, it will first reach the feeding section. Dry friction will inevitably occur in the feeding section. When these plastics are insufficiently heated and the melting is uneven, it is easy to cause increased wear on the inner wall of the barrel and the surface of the screw. Big. Similarly, in the compression section and the homogenization section, if the melting state of the plastic is disordered, it will also cause increased wear.
2. The rotational speed of the vertical injection molding machine should be adjusted properly. Because some plastics are added with reinforcing agents, such as fiberglass, minerals or other fillers. The friction of these substances on metal materials is often much greater than that of molten plastics. When injecting these plastics in a vertical injection molding machine, if the high speed is used, the shear force on the plastic will be increased, and the reinforcement will accordingly produce more shredded fibers. The shredded fibers contain The sharp end increases the wear force greatly. When inorganic minerals glide on the metal surface at high speed, its scraping effect is not small. Therefore, the speed should not be adjusted too high.