which steel is good to make injection mould

The working conditions of plastic molds are different from those of cold stamping molds. Generally, they must work at 150 ° C-200 ° C. In addition to being subjected to a certain pressure, they must also be affected by temperature. According to the different conditions and processing methods of plastic molding molds, the basic performance requirements of steel for plastic molds are roughly summarized as follows:

The hardness of plastic molds is usually below 50-60HRC. The heat-treated molds should have sufficient surface hardness to ensure that the molds have sufficient rigidity. Due to the large compressive stress and frictional force of the mold during the filling and flow of plastic, the mold is required to maintain the stability of shape accuracy and dimensional accuracy to ensure that the mold has a sufficient service life. The wear resistance of the mold depends on the chemical composition and heat treatment hardness of the steel, so increasing the hardness of the mold is conducive to improving its wear resistance.

In addition to EMD processing, most plastic molding molds need to be cut and machined. In order to extend the service life of cutting tools, improve cutting performance, and reduce surface roughness, the hardness of steel for plastic molds must be appropriate.

High-quality plastic products require small surface roughness values. For example, the surface roughness value of the cavity of the injection molding model is required to be less than Ra0.1 to 0.25, and the optical surface requires Ra <0.01nm. The cavity must be polished to reduce the surface roughness value. The steel selected for this purpose requires less material impurities, fine and uniform structure, no fiber orientation, and no pitting or orange peel defects should appear during polishing.

Plastic injection mold parts often have complex shapes and are difficult to process after quenching. Therefore, they should be selected to have good thermal stability. When the mold molding process is heat treated, the linear expansion coefficient is small, heat treatment deformation is small, and dimensional changes caused by temperature differences The rate is small, the metallographic structure and the die size are stable, and the machining can be reduced or eliminated, and the dimensional accuracy and surface roughness requirements of the die can be guaranteed.