What are the basic requirements of the common materials for injection moulds?
Reasonable selection of moulding materials is the first task of mold designers, and the basic requirements of mold materials are generally the following aspects.
1. Easy to processing mould parts for metal materials, some structure shape is complicated, in order to shorten the production cycle, improve efficiency, request mould material is easy to be processed into the shape of the drawings required and accuracy.
2. The gloss and precision of the surface of good wear resistance are directly related to the abrasion resistance of the mold cavity surface, especially in some plastics, glass fiber, inorganic filler and some.
Some pigments, they and the plastic melt in the runner and cavity with high flow velocity, friction on the surface of cavity is very big, if material not wear-resisting, will soon wear and damage to parts quality.
3. A lot of resin and additives have a corrosive effect on the surface of the cavity, which makes the surface of the cavity surface to be eroded and flayed, and the surface condition deteriorates and the quality of the plastic parts deteriorates.Therefore, it is better to use corrosion-resistant steel or chromium plating on the surface of the cavity.
4. Good dimensional stability during injection molding, the temperature of the mold cavity to reach above 300 ℃.For this, it is better to choose tool steel with proper tempering treatment (heat treatment steel).Otherwise, it will cause the change of the microstructure of the material, which will cause the change of the mold size.
5. The heat treatment effect is small in order to improve the hardness and wear resistance. Generally, the mold should be treated with heat treatment, but this treatment should make its size change very small.Therefore, it is better to use pre-hardened steel that can be machined.
6. Good polishing performance plastics usually require good gloss and surface state, so the cavity surface roughness is very small, so, the cavity surface must be surface processing, such as polishing, grinding, etc.Therefore, the selected steel should not contain coarse impurities and pores.