According to different working conditions and processin […]
According to different working conditions and processing methods of injection molds, the basic performance requirements of injection mold steel are summarized:
Sufficient surface hardness and wear resistance. The hardness of injection mold steel is usually below 50-60hrc, and the injection mold after heat treatment should have sufficient surface hardness to ensure that the injection mold has sufficient hardness. Since the injection mold is filled under high pressure, high friction and high flow, the accuracy of the injection mold is required to maintain the stability of the shape and dimensional accuracy of the mold, and to ensure the service life of the injection mold. The wear resistance of the injection mold depends on the chemical composition and heat treatment hardness of the steel, thereby increasing the hardness of the injection mold.
Good processing performance. In addition to EMD processing, most plastic molding molds also require certain cutting processing and assembly. In order to extend the service life of the mold, improve the cutting performance, and reduce the surface roughness, the hardness of the mold must be appropriate.
Good polishing performance. High-quality plastic products require less cavity surface roughness. For example, the surface roughness of the injection mold cavity is required to be less than Ra0.1 ~ 0.25, while the optical surface requires Ra<0.01nm. In order to reduce the surface roughness, the cavity must be polished. The selected steel requires less impurities, uniform structure, no fiber orientation, and no pitting or orange peel defects during polishing.
Good thermal stability. The shape of the plastic injection mold parts is more complicated and the quenching process is difficult. Therefore, it should be selected to have good thermal stability as much as possible. After the mold is processed with a small linear expansion coefficient, heat treatment, the heat treatment deformation is small, and the temperature difference caused by the rate of change is small, and the temperature difference is small. The structure and size of the mold are stable, which can be reduced or no longer processed, and the dimensional accuracy and surface roughness requirements of the injection mold can be guaranteed.