Excellent machinability: Most plastic moulds need to be machined and repaired by fitters besides EMD. In order to prolong the service life of cutting tools, improve cutting performance and reduce surface roughness, the hardness of steel for plastic die must be appropriate.

Good polishing performance: High quality plastic products require small surface roughness. For example, the surface roughness of injection mold cavity is required to be less than Ra 0.1-0.25 level, while the optical surface of aluminium heating plate manufacturer is required to be Ra < 0.01 nm, and the cavity must be polished to reduce the surface roughness value. For this reason, the selected steel requires less impurities, uniform microstructure, no fiber orientation, and no pitting or orange peel defects in polishing.

Good thermal stability: Plastic injection mold parts are often complex in shape and difficult to process after quenching. Therefore, good thermal stability should be selected as far as possible. When the mold is processed after heat treatment, the linear expansion coefficient is small, the heat treatment deformation is small, the size change rate caused by temperature difference is small, the metallographic structure and the size of the mold are stable, and can be reduced or no longer processed. The requirement of dimension accuracy and surface roughness of die can be guaranteed.