Vertical injection molding machine screws work 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 wear caused by friction is unavoidable. Generally, the screw of the vertical injection molding machine has been subjected to a 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 ignored, if we do not try to reduce the wear of the vertical injection molding machine as much as possible, the working life of the screw of the vertical injection molding machine will be greatly reduced.
The reasons for the wear of the screw of the vertical injection molding machine and the methods of reducing the wear are described below.
1. Each plastic has an ideal plasticizing processing temperature range. The processing temperature of the barrel of the vertical injection molding machine should be controlled to bring it closer to this temperature range. Granular plastic enters the vertical injection molding machine barrel from the hopper, and will first reach the feeding section. Dry friction will inevitably occur in the feeding section. When these plastics are insufficiently heated and unevenly melted, it is easy to cause increased wear on the inner wall of the barrel and the screw surface. Big. Similarly, in the compression section and the homogenization section, if the molten state of the plastic is disordered and uneven, the wear will also increase.
2. The speed of 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 materials on metallic materials is often much greater than that of molten plastic. When injecting these plastics in a vertical injection molding machine, if the high speed is used, while increasing the shear force on the plastic, it will also strengthen the production of more shredded fibers. The shredded fibers contain The sharp ends increase 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.