1. Nitriding
Nitriding processes include gas nitriding, ion nitriding and liquid nitriding. In each nitriding method, there are several nitriding technologies, which can adapt to the requirements of different steel grades and different workpieces. Because the nitriding technology can form a surface with excellent performance, and the nitriding process is well coordinated 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 mold The surface strengthening of the nitriding technology is earlier and the most widely used.
2. Carburizing
The purpose of mold carburizing is mainly 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 technical idea introduced from this is to use lower-grade materials, that is, to replace higher-grade materials by carburizing and quenching, thereby reducing manufacturing costs.
3. Hardened film deposition
Hardened film deposition technology, currently more mature is CVD and PVD. In order to increase the bonding strength between the film layer and the surface of the workpiece, a variety of enhanced CVD and PVD technologies have now been developed.
Hardened film deposition technology was first applied to tools (knives, cutting tools, measuring tools, etc.) with excellent results. Many kinds of tools have adopted hardened film coating as a standard process.
Molds have been coated with hardened film technology since the 1980s. Under the current technical conditions, the cost of hardened film deposition technology (mainly equipment) 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, the overall level of mold manufacturing in my country can be improved.
Fourth, the pre-hardening technology of mold materials
In the mold manufacturing process, heat treatment is a process that most molds use for a long time. 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. Therefore, the research and development of pre-hardening technology has not invested much.
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%), my country began to use pre-hardened modules (mainly imported products) in the mid to late 1990s.
The pre-hardening technology of mold materials is mainly developed and implemented by mold material manufacturers. By adjusting the chemical composition of the steel and equipping the corresponding heat treatment equipment, it is possible to mass-produce pre-hardened modules with stable quality. The pre-hardening technology of mold materials in my country has a late start and small scale, and currently it cannot meet the requirements of domestic mold manufacturing.
The use of pre-hardened mold materials can simplify the mold manufacturing process, shorten the mold manufacturing cycle, and improve the manufacturing accuracy of the mold. It is foreseeable that with the advancement of processing technology, pre-hardened mold materials will be used in more mold types.