The die-casting mold is a major category in the mold. With the rapid development of China's automobile and motorcycle industry, casting industry has ushered in a new period of development. , But also put forward higher requirements for the comprehensive mechanical properties of die-casting mold, life. To meet the increasing use of performance requirements rely solely on the application of the new mold material is still difficult to meet, must be a variety of surface treatment technology applied to the surface treatment of the die-casting mold in order to achieve the high efficiency of the die-casting mold, high precision and high life to be. Various molds, die casting mold, working conditions are more demanding. Pressure casting molten metal is full of mold cavity under high pressure, high-speed die casting forming repeatedly in the course of their work, contact with hot metal, thus requiring the die-casting mold has a higher thermal fatigue, thermal conductivity, wear resistance, corrosion , impact toughness, red hardness, good mold release and so on. Therefore, require a higher die-casting mold surface treatment technology in recent years, a variety of die-casting mold surface to handle new technologies are emerging, but in general can be divided into three broad categories:
(1) the conventional heat treatment process to improve technology;
(2) surface modification techniques, including surface thermal diffusion treatment, the surface phase transformation strengthening EDM enhancement technology;
(3) coating techniques, including electroless plating, etc..
Traditional die-casting mold heat treatment process is quenched - tempered, and later developed a surface treatment technology. Due to a variety of materials can be used as die-casting mold, the same surface treatment technologies and processes used in the different materials will produce different results. History of Markov recently proposed substrate pretreatment technologies mold substrate and surface treatment technology, on the basis of traditional craft of different mold materials for the process, thus improving mold performance, increase die life. Another direction of development, improved by heat treatment technology is the combination of the traditional heat treatment process with advanced surface treatment technology to improve the service life of die-casting mold. If the chemical heat treatment method of carbon and nitrogen permeation and conventional quenching and tempering process of combining NQN (carbonitriding - quenching - carbon and nitrogen permeation) composite strengthening, not only to obtain a higher surface hardness and effective case depth increases, the layer hardness gradient distribution reasonable, tempering stability and corrosion resistance, making casting molds, surface quality and performance of a substantial increase in the same time get a good core part performance.
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