In addition to high enough strength and toughness, the surface properties of high-precision mold parts are very important to the working performance and service life of high-precision mold parts. The improvement of these properties, relying solely on the improvement and improvement of the matrix material is very limited and uneconomical, and through the surface treatment technology, it is often possible to get twice the result with half the effort, which is also the reason for the rapid development of surface treatment technology. Mold polishing technology is an important part of mold surface engineering and an important post-processing process in the mold manufacturing process. Due to certain problems in domestic polishing technology and materials, such as point-and-shoot camera lens injection molds, CD, VCD discs and injection molds that require high transparency of tools still rely on imports for a large part.
The mirror mold material is not only a matter of chemical composition, but also requires a series of advanced processes such as vacuum degassing, argon protection ingot, vertical continuous casting and rolling, and soft forging during smelting, so that the mirror mold steel has fewer internal defects. It has a series of advantages such as fine impurity particle size, high dispersion degree, fine metal grain size and good uniformity, so as to meet the requirements of mold steel polished to mirror surface. The surface treatment technology of mold parts is a systematic engineering of changing the surface morphology, chemical composition, organizational structure and stress state of high-precision mold parts to obtain the required surface properties through surface coating, surface modification or composite treatment technology. The nitriding process includes gas nitriding, ion nitriding, liquid nitriding, etc. In each nitriding method, there are several nitriding technologies, which can adapt to the requirements of different steel grades and different workpieces. From the surface treatment method, it can be divided into: chemical method, physical method, physical chemical method and mechanical method.

It is worth noting that the polishing of the mold surface is not only affected by the polishing equipment and process technology, but also by the mirror surface of the mold material, which has not attracted enough attention, that is to say, the polishing itself is restricted by the mold material. Although new processing technologies aimed at improving the surface properties of precision mold parts are constantly emerging, nitriding, carburizing and hard film deposition are the most widely used in the manufacture of high-precision mold parts. Because the nitriding technology can form a surface with excellent performance, and the nitriding process has good coordination with the quenching process of high-precision mold parts steel, and the nitriding temperature is low, and no intense cooling is required after nitriding, and the deformation of high-precision mold parts It is extremely small, so the surface strengthening of high-precision mold parts is the earliest and most widely used nitriding technology.