Metal cutting is one of the most basic machining methods in mechanical manufacturing. With the development of modern science and technology, cutting is developing towards high efficiency and high quality. Therefore, how to improve the service life and working reliability of cutting tools and how to determine the durability of cutting tools have become prominent problems. There are many factors affecting tool life. On the premise that the tool has a certain toughness and strength, the main factor affecting the service life of the tool is wear resistance, because wear is the main failure form of the tool. Although the types of wear are different, the main failure modes of metal cutting tools are adhesive wear and abrasive wear. Figure 1 shows the scanning morphology of the worn surface of the milling cutter after wear failure. There are obvious adhesion pits and wear marks caused by hard particles on the worn surface. The ultra-low temperature treatment process of industrial refrigerator is the follow-up process of normal treatment process. It can improve the microstructure and mechanical properties of materials, especially the wear resistance. In this paper, M2 high speed steel milling cutter is selected as the research object, and its ultra-low temperature treatment process is carried out. Under the same working conditions, the actual cutting life test is carried out on the milling cutter wear scanning morphology in Fig. 1. The results show that the performance of M2 steel milling cutter is obviously improved after ultra-low temperature treatment, and the service life is increased by more than one time.
After tempering at 550 ° C, the quenched M2 steel was immediately put into the ultra-low temperature treatment equipment with industrial freezer. The specific heat treatment and ultra-low temperature treatment process of M 2 steel milling cutter. After ultra-low temperature treatment, the microstructure of the steel has the following changes: almost all retained austenite in the original steel is transformed into hard and stable martensite structure, and the original martensite structure is micronized, at the same time, a large number of fine and hard carbide particles disperse and fold out. The M 2 steel milling cutter was installed on a special machine tool to process 6 twist drill bit. The drill bit was made of annealed T1 (AISI) high speed steel, and its hardness was in the range of hb252-207. The cooling cutting fluid was used in the processing. The actual durability of the tool is mainly determined by the surface roughness of the product and the actual cutting difficulty. Compared with the test results, it can be seen that the M2 steel milling cutter without ultra-low temperature treatment usually needs to be reground or scrapped when machining 90-115 pieces of drill bits before ultra-low temperature treatment, while the M 2 milling cutter after ultra-low temperature treatment can process 200-300 pieces of drill bits before regrinding or scrapping, and the service life is significantly improved.