Vertical injection molded screws operate for a long time under conditions of high temperature, high pressure, high mechanical moment and high friction media. The first few factors are required by the process conditions, and wear caused by friction is inevitable. Typically, the auger of a vertical injection molding machine was nitrided to improve surface hardness, that is, to increase wear resistance. However, if the cause of the wear of the vertical injection molding machine is ignored, and the wear of the vertical injection molding machine is not reduced as much as possible, the service life of the screw of the vertical injection molding machine will be significantly reduced.
The causes of wear of the auger of a vertical injection molding machine and methods for reducing wear are described below.
1. Each plastic has an ideal plasticization temperature range. The processing temperature of the cylinder of the vertical injection molding machine should be controlled to bring it closer to this temperature range. Granular plastic enters the barrel of a vertical injection molding machine from the hopper and first reaches the feed section. Dry friction will inevitably occur in the feed section. When these plastics are not sufficiently heated and unevenly melted, it is easy to cause increased wear on the inner wall of the cylinder and on the surface of the screw. Big. Similarly, in the compression section and the homogenization section, if the molten state of the plastic is disordered and uneven, wear will also increase.
2. The speed of the vertical injection molding machine should be adjusted correctly. 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 these plastics are injected into a vertical injection molding machine, if high speed is used, while increasing the shear forces on the plastic, this will also increase the production of finer fibers. Shredded fibers contain sharp ends, significantly increasing the strength of wear. When inorganic minerals glide over the surface of a metal at high speed, its scratching effect is not small. Therefore, the speed should not be adjusted too high.