Mold surface treatment is a systematic engineering of changing the morphology, chemical composition, structure and stress state of the mold surface through surface coating, surface modification or composite treatment technology to obtain the required surface properties.
From the surface treatment method, it can be divided into: chemical method, physical method, physical chemical method and mechanical method. Although new processing technologies to improve the surface performance of molds continue to emerge, carburizing, nitriding, and hardened film deposition are more commonly used in mold manufacturing.
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.
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, so the surface of the mold Intensification is the earlier nitriding technology and the most widely used.
Hardened film deposition technology is currently more mature CVD, PVD. In order to increase the bonding strength of the surface of the film layer 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 improvement can be achieved.
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