These six requirements for plastic mold not be ignored
- 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, peel off, deteriorate the surface condition, and deteriorate the quality of the plastic parts. Therefore, use corrosion-resistant steel, or carry out chrome plating and cymbal nickel treatment on the surface of the cavity.
- Good wear resistance
The gloss and precision of the surface of plastic parts are directly related to the wear resistance of the surface of the plastic mold cavity, especially when glass fibers, inorganic fillers and some pigments are added to some plastics, they are mixed with the plastic melt. The high-speed flow in the runner and the cavity has a large friction on the surface of the cavity. If the material is not wear-resistant, it will wear quickly and damage the quality of the plastic parts.
- Good dimensional stability
During plastic molding, the temperature of the plastic mold cavity should reach above 300 °C. For this reason, it is best to choose tool steels (heat-treated steels) that have been appropriately tempered. Otherwise, it will cause changes in the microstructure of the material, resulting in changes in the size of the plastic mold.
- Easy to process
Most of the mold parts are made of metal materials, and some of them have complex structures and shapes. In order to shorten the production cycle and improve the efficiency, the mold materials are required to be easy to process into the shape and precision required by the drawings.
- Good polishing performance
Plastic parts are usually required to have good gloss and surface condition, so the roughness of the cavity surface is required to be very small. In this way, the surface of the cavity must be subjected to surface processing, such as polishing, grinding, etc. Therefore, the selected steel should not contain rough impurities and pores.
- Less affected by heat treatment
In order to improve the hardness and wear resistance, the plastic mold is generally subjected to heat treatment, but this treatment should make the dimensional change small. Therefore, pre-hardened steel that can be machined is used.