The hardness of plastic mold is usually below 50-60HRC, and the mold after heat treatment should have enough surface hardness to ensure that the mold has enough stiffness.  Mold in the work because of the plastic filling and flow to bear large compressive stress and friction, the mold is required to maintain the stability of shape accuracy and dimensional accuracy, to ensure that the mold has enough service life.  The wear resistance of die depends on the chemical composition of steel and the hardness of heat treatment, so improving the hardness of die is beneficial to improve its wear resistance.