The six requirements for purchasing plastic molds cannot be ignored

Plastic mold is a combination mold used for compression molding, extrusion molding, injection molding, blow molding, and low foam molding. The coordinated changes between the convex and concave molds of the mold and the auxiliary forming system can process a series of plastic parts with different shapes and sizes. In order to meet the needs of formed components, we need to pay attention to some considerations when selecting plastic molds and propose corresponding requirements. The following six requirements need to be met when selecting a more suitable plastic mold.

1. Many resins and additives with high corrosion resistance have a corrosive effect on the surface of the mold cavity. This corrosion causes the metal on the surface of the mold cavity to dissolve, peel off, deteriorate the surface condition, and deteriorate the quality of the plastic parts. Therefore, it is best to use corrosion-resistant steel or chrome or nickel plating treatment on the surface of the mold cavity.

2. Good wear resistance. The glossiness 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, they flow rapidly in the flow channel and cavity together with the plastic melt, causing significant friction on the cavity surface. If the material is not wear-resistant, it will quickly wear out, causing damage to the quality of the plastic parts.

3. Good dimensional stability requires the temperature of the plastic mold cavity to reach over 300 ℃ during plastic molding. For this reason, it is best to choose tool steel (heat treated steel) that has undergone appropriate tempering treatment. Otherwise, it will cause changes in the microstructure of the material, resulting in changes in the size of the plastic mold.

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

5. Plastic parts with good polishing performance usually require good gloss and surface condition, so the roughness of the cavity surface is required to be very small. Therefore, surface processing such as polishing, grinding, etc. must be carried out on the cavity surface. Therefore, the selected steel should not contain rough impurities and pores.

6. To improve hardness and wear resistance, plastic molds are generally subjected to heat treatment, but this treatment should minimize dimensional changes. Therefore, it is best to use pre hardened steel that can be machined.