Injection mold is a tool for producing plastic products. In order to meet the needs of molded parts, we need to pay attention to some things when choosing injection molds and put forward corresponding requirements. The following six requirements need to be met to choose a more suitable injection mold.
1. 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 the plastic parts deteriorates. Therefore, use corrosion-resistant steel, or perform chromium plating and cymbal nickel treatment on the cavity surface.
2. Good wear resistance. The gloss and accuracy of the surface of injection molded plastic parts are directly related to the wear resistance of the surface of the injection mold cavity, especially when glass fiber, inorganic fillers and certain pigments are added to some plastics, they are combined with the plastic melt. The high-speed flow in the runner and mold cavity will cause great friction on the surface of the cavity. If the material is not wear-resistant, it will wear out quickly, which will damage the quality of the plastic part.
3. Good dimensional stability. During injection molding, the temperature of the injection mold cavity must reach 300°C or more. For this reason, select tool steel (heat-treated steel) that has been properly tempered. Otherwise, the microstructure of the material will change, which will cause the size of the injection mold to change.
4. Easy to process. Most of the mold parts are 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.
5. Good polishing performance. Injection molded parts usually require good gloss and surface condition, so the roughness of the cavity surface is required to be very small, so that 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.
6. Less affected by heat treatment. In order to improve the hardness and wear resistance, the injection mold is generally heat treated, but this treatment should make the size change small. Therefore, pre-hardened steel that can be cut is used.