The plastic mold is an abbreviation for a combined mold for compression molding, extrusion molding, injection molding, blow molding and low foam molding. The coordinated changes of the mold convex and concave molds and the auxiliary forming system can process a series of plastic parts of different shapes and sizes. In order to meet the needs of molded parts, we need to pay attention to some matters when selecting plastic molds, and put forward corresponding requirements. The choice of a more suitable plastic mold below needs to meet the six requirements.
1. High Corrosion Resistance Many resins and additives have corrosive effects on the surface of the cavity. This corrosion causes the surface of the cavity to corrode and peel off, the surface condition deteriorates, and the quality of the molded part deteriorates. Therefore, it is best to use corrosion-resistant steel or chrome-plated, nickel-plated surfaces on the cavity surface.
2, good wear resistance, the gloss and precision of the surface of plastic parts are directly related to the wear resistance of the surface of plastic mold cavity, especially when some plastics add glass fiber, inorganic filler and some pigments, they Together with the plastic melt, it flows at idle speed in the flow channel and the cavity. The friction on the surface of the cavity is very large. If the material is not wear-resistant, it will wear quickly and the quality of the plastic part will be damaged.
3, good dimensional stability In the plastic molding, the temperature of the plastic mold cavity should reach 300 ° C or more. For this reason, it is preferable to use a suitably tempered tool steel (heat treated steel). Otherwise, it will cause a change in the microstructure of the material, resulting in a change in the size of the plastic mold.
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, improve efficiency, mold materials are required to be easily processed into the shape and precision required by the drawings.
5, good polishing performance Plastic parts are usually required to have a good gloss and surface state, so the surface roughness of the cavity is required to be very small, so the surface of the cavity must be surface processing, such as polishing, grinding and so on. Therefore, the selected steel should not contain rough impurities and pores.
6. Small effect by heat treatment In order to improve hardness and wear resistance, plastic molds are generally heat treated, but this treatment should have small dimensional changes. Therefore, it is preferable to use a pre-hardenable steel that can be machined.