What are the basic material requirements commonly used in injection molds?

Update:10-07-2020
Summary:

Reasonable selection of mold-making materials is the pr […]

Reasonable selection of mold-making materials is the primary task of mold designers. Generally, the basic requirements for mold materials are as follows.

1. Easy to process, most of the mold parts are made of metal materials, and auto Cap machine some structural shapes are still very complicated. In order to shorten the production cycle and improve efficiency, the mold materials are required to be easily processed into the shape and accuracy required by the drawings.
Pipe Fitting Mould
2. Good abrasion resistance The glossiness and precision of the surface of the plastic parts are directly related to the abrasion resistance of the mold cavity surface, especially when some fibers are added with glass fiber, inorganic fillers and certain pigments. The melt flows fast in the flow channel and the mold cavity together, and the friction on the surface of the cavity is very large. If the material is not wear-resistant, it will quickly wear out and damage the quality of the plastic parts.

3. 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 is deteriorated, and the quality of the plastic parts is deteriorated. Therefore, it is best to use corrosion-resistant steel, or chromium and nickel plating the cavity surface.

4. Good dimensional stability During injection molding, the temperature of the mold cavity should reach above 300℃. For this reason, it is best to use tool steel (heat-treated steel) that has been properly tempered. Otherwise, it will cause changes in the microstructure of the material, resulting in changes in the size of the mold.

5. Less influenced by heat treatment In order to improve the hardness and wear resistance, the mold is generally heat treated, but this treatment should make its size change small. Therefore, it is best to use pre-hardened steel that can be cut.

6. Good polishing performance Plastic parts usually require good gloss and surface condition, so the roughness of the cavity surface is very small. In this way, the cavity surface must be surface-processed, such as polishing and grinding. Therefore, the selected steel should not contain rough impurities and pores.