Plastic mold is an abbreviation for a combined mold used for compression molding, extrusion molding, injection, blow molding and low foam molding. The coordinated changes of mold convex and concave molds and auxiliary molding system can process a series of plastic parts of different shapes and different sizes. In order to meet the needs of molded parts, we need to pay attention to some things when choosing plastic molds and put forward corresponding requirements. The following six requirements need to be met to choose a more suitable plastic 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 be corroded and peeled off, the surface condition deteriorates, and the quality of the plastic parts deteriorates. Therefore, it is best to use corrosion-resistant steel, or chromium plating, cymbal nickel treatment on the surface of the cavity.
2. Good wear resistance. The gloss and accuracy of the surface of plastic parts are directly related to the wear resistance of the surface of the plastic mold cavity, especially when glass fiber, inorganic fillers and certain pigments are added to some plastics. Together with the plastic melt, it flows at high speed in the runner and mold cavity, and it has 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 plastic molding, the temperature of the plastic mold cavity must reach above 300°C. For this reason, it is best to 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 plastic mold to change.
4. Easy-to-process 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.
5. Good polishing performance. Plastic 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.
6. Less affected by heat treatment In order to improve the hardness and wear resistance, the plastic mold is generally heat treated, but this treatment should make the size change small. Therefore, it is best to use pre-hardened steel that can be machined.
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