High-precision mold fittings in the work in addition to the requirements of sufficiently high strength and toughness, its surface properties of high-precision mold fittings work performance and service life is critical. Improvement of these properties, relying solely on the improvement of the matrix material and enhancement is very limited, is also not economic, and through the surface treatment technology, often can receive twice the result with half the effort, which is precisely the reason why the surface treatment technology has been rapid development. Mold polishing technology is an important part of the mold surface engineering, mold manufacturing process is an important process of post-treatment. Due to the domestic polishing technology and materials and other aspects of the process there are still some problems, so such as stupid camera lens injection mold, CD, VCD discs and tools with high transparency requirements of the injection mold is still a large part of the dependence on imports.
Mirror mold material is not only the chemical composition of the problem, more importantly, the smelting requires the use of vacuum degassing, argon protection ingot, vertical continuous casting and rolling, soft forging and a series of advanced technology, so that the mirror mold steel with fewer internal defects, impurities fine particle size, dispersion degree is high, the metal grain size is fine, uniformity, and so on a series of advantages in order to achieve the polished to the mirror surface of the mold steel requirements. Mold fittings surface treatment technology, is through the surface coating, surface modification or composite treatment technology, change the surface of high precision mold fittings morphology, chemical composition, organizational structure and stress state, in order to obtain the required surface properties of the system engineering. Nitriding process has gas nitriding, ion nitriding, liquid nitriding and other ways, each of which has a number of nitriding technology, which can be adapted to the requirements of different steel different workpieces. From the way of surface treatment, it can be divided into: chemical method, physical method, physical-chemical method and mechanical method.
It is worth noting that the mold surface polishing is not only affected by polishing equipment and process technology, but also by the mold material mirror degree of influence, which has not yet attracted enough attention, that is, the polishing itself by the mold material constraints. Although aimed at improving the surface performance of precision mold parts of the new treatment technology continues to emerge, but in the manufacture of high-precision mold parts more applications are mainly nitriding, carburizing and hardening film deposition. As nitriding technology can form excellent performance of the surface, and nitriding process and high precision mold parts steel quenching process has a good coordination, while nitriding low temperature, nitriding after intense cooling is not required, high precision mold parts deformation is extremely small, so high precision mold parts surface strengthening is the use of nitriding technology earlier, but also the most widely used.
