Several aspects needing attention in reducing the screw wear of injection molding machine

The screw of injection molding machine works long time under high temperature, high pressure, high mechanical torque and high friction. These factors are required by technological conditions, and the attrition caused by friction is inevitable.

Generally, the screw has been subject to surface nitriding treatment to improve the surface hardness, that is, to improve the wear resistance. However, if the causes of wear are ignored and the wear is not reduced as much as possible, the working life of the screw will be greatly reduced.

The following will focus on the causes of screw wear and the methods to reduce wear:

Each plastic has an ideal plasticizing processing temperature range. The processing temperature of the barrel should be controlled to make it close to this temperature range. When granular plastics enter the barrel from the hopper, they will first reach the feeding section. Dry friction will inevitably occur in the feeding section. When these plastics are not heated enough and melt unevenly, it is easy to increase the wear of the inner wall of the barrel and the surface of the screw.

Similarly, in the compression section and homogenization section, if the melting state of the plastic is disordered and uneven, it will also increase the wear.

The speed should be adjusted properly. Some plastics are fortified, such as glass fiber, minerals or other fillers. The friction force of these substances on metal materials is often much greater than that of molten plastics. When these plastics are injected, if they are made at a high speed, while increasing the shear force on the plastics, the reinforcement will correspondingly produce more torn fibers. The torn fibers contain sharp ends, which greatly increases the wear force.

When inorganic minerals slide at high speed on the metal surface, their scraping effect is not small. Therefore, the speed should not be adjusted too high.