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Surface Treatment Technology in Die Casting Mould

update:25-03-2021
abstract:

Die-casting molds are a large category of molds. With t […]

Die-casting molds are a large category of molds. With the rapid development of my country's automobile and motorcycle industry, the die-casting industry has ushered in a new period of development. At the same time, higher requirements are put forward on the comprehensive mechanical properties and life of die-casting molds. It is still difficult to meet the ever-increasing performance requirements that only rely on the application of new mold materials. Various surface treatment technologies must be applied to the surface treatment of die-casting molds to achieve the requirements for high efficiency, high precision and long life of die-casting molds. . Die casting is to fill the mold cavity with molten metal under high pressure and high speed and die-casting. It repeatedly contacts the hot metal during the working process. Therefore, the die-casting mold is required to have high thermal fatigue, thermal conductivity, wear resistance, and corrosion resistance. , Impact toughness, red hardness, good mold release, etc. Therefore, the surface treatment technology requirements for die-casting molds are relatively high. In recent years, a variety of new die-casting mold surface treatment technologies have emerged, but in general, they can be divided into the following three categories: (1) Traditional heat treatment process improvement technology; (2) Surface modification technology, including surface thermal expansion treatment, surface phase change strengthening, electric spark strengthening technology, etc.; (3) Coating technology, including electroless plating, etc.

Improved technology of traditional heat treatment process
The traditional heat treatment process of die-casting molds is quenching-tempering, and later surface treatment technology has been developed. Due to the variety of materials that can be used as die-casting molds, the same surface treatment technology and process applied to different materials will produce different effects. Schoff recently proposed a substrate pretreatment technology for mold substrate and surface treatment technology, and proposed suitable processing techniques for different mold materials on the basis of traditional processes, so as to improve mold performance and increase mold life. Another development direction for the improvement of heat treatment technology is to combine traditional heat treatment technology with advanced surface treatment technology to increase the service life of die-casting molds. For example, the chemical heat treatment method carbonitriding, NQN (namely carbonitriding-quenching-carbonitriding) combined with the conventional quenching and tempering process is combined to strengthen, not only to obtain higher surface hardness, but also effective hardening The layer depth increases, the hardness gradient distribution of the infiltrated layer is reasonable, the tempering stability and the corrosion resistance are improved, so that the die-casting mold obtains good core performance, while the surface quality and performance are greatly improved.