What are the commonly used injection materials?

Commonly used plastic materials for injection automotive mould: ABS, PP, PVC, PC.

Common commonly used materials for molds: yellow-label materials, P20, 718, 738, S136.

Generally, the basic requirements for injection mold materials have the following aspects.

1. Easy to process Injection mold parts are mostly made of metal materials, and some structural shapes are still very complex. In order to shorten the production cycle and improve efficiency, the mold materials are required to be easy to process into the shape and accuracy required by the drawings.

2. Good wear resistance. The gloss and precision of the surface of the plastic part are directly related to the wear resistance of the mold cavity surface, especially when glass fiber, inorganic fillers and certain pigments are added to some plastics. The melt flows at high speed in the runner and the mold cavity together, and the friction on the surface of the cavity is great. If the material is not wear-resistant, it will wear out quickly, which will damage the quality of the plastic part.

3. High corrosion resistance Many resins and additives have a corrosive effect on the surface of the cavity. This corrosion causes the metal on the surface of the cavity to corrode and peel off, the surface condition becomes worse, and the quality of plastic parts deteriorates. Therefore, it is necessary to use corrosion-resistant steel, or perform chromium plating and cymbal nickel treatment on the surface of the cavity.

4. Good dimensional stability. During injection molding, the temperature of the injection mold cavity must reach above 300°C. For this reason, it is necessary to select tool steel (heat-treated steel) that has been properly tempered. Otherwise it will cause changes in the microstructure of the material, resulting in changes in the size of the mold.

5. Less affected by heat treatment In order to improve the hardness and wear resistance, the mold is generally heat treated, but this treatment should make the size change small. Therefore, it is necessary to use pre-hardened steel that can be machined.

6. Good polishing performance. Plastic parts usually require good gloss and surface condition. Therefore, the roughness of the cavity surface is required to be very small. In this way, the surface of the cavity must be surface processed, such as polishing, grinding, etc. Therefore, the selected steel should not contain rough impurities and pores.