Common plastic raw materials for injection molding: ABS, PP, PVC, PC,PPS.
Common materials commonly used in molds: yellow card materials, P20, 718, 738, S136.
Generally, the basic requirements for injection mold materials are as follows.
- 1. Easy to process Injection mold parts are mostly made of metal materials, and some structural shapes are still very complicated. In order to shorten the production cycle and improve efficiency, mold materials are required to be easily cnc machined into the shape and accuracy required by drawings.
- 2. Good abrasion resistance The surface gloss and accuracy of plastic parts are directly related to the abrasion resistance of the mold cavity surface, especially when some plastics are added with glass fiber, inorganic fillers and certain pigments, they and plastic The melt flows at a rapid speed in the flow channel and the mold cavity together, and the friction on the surface of the cavity is very large. If the material is not abrasion-resistant, it will wear quickly and damage the quality of the plastic part.
- 3. High corrosion resistance Many resins and additives have a corrosive effect on the cavity surface. This corrosion causes the metal on the cavity surface to dissolve and peel off, the surface condition is deteriorated, and the quality of the plastic parts is deteriorated. Therefore, it is best to use corrosion-resistant steel, or chrome-plated and samarium-nickel treatment on the cavity surface.
- 4. Good dimensional stability During injection molding, the temperature of the cavity of the injection mold must reach above 300 ° C. For this reason, it is best to select a tool steel (heat-treated steel) that has been appropriately tempered. Otherwise, the microstructure of the material will be changed, which will cause the size of the mold to change.
- 5. Less affected by heat treatment In order to improve the hardness and wear resistance of the mold, heat treatment is generally performed on the mold, but this treatment should make the size change small. Therefore, it is best to use pre-hardened steel that can be machined.
- 6. Good polishing performance Plastic parts usually require good gloss and surface conditions, so the roughness of the cavity surface is very small. In this way, the surface of the cavity must be surface treatment, such as polishing and grinding. Therefore, the selected steel should not contain rough impurities and pores.