In addition to the reasonable combination of high enough strength and toughness of the matrix during the work of the mold, its surface properties are very important to the working performance and service life of the mold. Mold surface treatment technology, pvd coating machine surface coating, surface modification or composite treatment technology, to change the morphology, chemical composition, structure and stress state of the mold surface to obtain the required surface performance. At present, nitriding, carburizing and hardened film deposition are mainly used in mold manufacturing.

        The pvd coating machine can form a surface with excellent performance due to the nitriding technology, and the nitriding process has a good coordination with the quenching process of the die steel. At the same time, the nitriding temperature is low, no intense cooling is required after nitriding, and the deformation of the mold is extremely small. Therefore, the surface strengthening of the mold adopts the nitriding technology earlier and is the most widely used.
        The carburizing of the pvd coating machine mold is to improve the overall strength and toughness of the mold, that is, the working surface of the mold has high strength and wear resistance. The hardened film deposition technology of pvd coating machine is currently more mature cvd and pvd. The mold has been coated with hardened film technology since the 1980s. Under current technical conditions, the cost of hardened film deposition technology (mainly equipment) for pvd coating machine is relatively high, and it is still only applied to some precision and long-life molds. If a heat treatment center is established, the cost of coating hardened film Will be greatly reduced, if more molds adopt this technology, it can improve the overall level of mold manufacturing in my country.
         Since the 1970s, the idea of pre-hardening has been proposed internationally. However, due to the constraints of the rigidity of the processing machine tool and the cutting tool, the hardness of the pre-hardening cannot reach the hardness of the mold, so the R&D investment in pre-hardening technology is not large. With the improvement of the performance of processing machine tools and cutting tools, the development of pre-hardening technology for mold materials has accelerated. By the 1980s, the proportion of internationally industrialized countries that used pre-hardened modules on plastic mold materials had reached 30% (currently Above 60%).