Bimetallic screw is operated under high temperature, hi […]
Bimetallic screw is operated under high temperature, high pressure and high friction. Although the loss of bimetallic screw caused by these factors is inevitable, it is also a necessary condition for the production process. Generally, the screw has been nitrided on the surface to improve the surface hardness, which is to improve the ability of wear resistance. However, if the cause of wear is neglected and the wear is not reduced as much as possible, the working life of screw will be greatly reduced.
1. Each plastic raw material has a desired plasticizing processing temperature scale, so the barrel processing temperature should be controlled to make it close to this temperature scale. Granular plastic from the hopper into the barrel, will first arrive at the feeding section, in the feeding section will inevitably show dry friction, when these plastics lack of heat, melting uneven, it is easy to form the barrel wall and screw surface wear increased; the same, in the contraction section and homogenization section, if the plastic melting status is disorderly uneven, it will also form wear increase.
2. The speed should be adjusted properly. Because some plastics are reinforced, such as fiberglass, minerals or other fillers. The friction force of these substances on metal raw materials is often much greater than that of molten plastics. In the injection molding of these plastics, if you use a high speed, then the improvement of the shear force on the plastic together, will also make the reinforcement corresponding to more torn fibers, the torn fibers contain a sharp end, so that the wear force is greatly added. The scraping effect of inorganic minerals on metal surface is not small. Therefore, the speed should not be adjusted too high.