Whether There Is A Market For Superhard Tool Materials in The Future

With the development of material industry and precision machinery industry, the use of precision cutting, ultra-precision cutting and difficult cutting materials is increasing, and the application of ultra-hard tool materials is increasingly extensive. Superhard material tool has the characteristics of high efficiency, long service life and good processing quality. In the past, it is mainly used for finishing. In recent years, due to the improvement of the production process of artificial superhard tool material, the control of raw material purity and grain size, the use of composite materials and hot pressing process, the scope of application is expanding, in addition to suitable for general finishing and semi-finishing, but also can be used for rough processing. It is internationally recognized as one of the most productive tool materials of our time. By using superhard materials to process steel, cast iron, non-ferrous metals and alloys, the cutting speed is one order of magnitude higher than that of hard alloy, and the tool life is dozens or even hundreds of times higher than that of hard alloy. At the same time, the appearance of it also changes the traditional technology concept. The ultra-hard tool can be used directly to turn and mill instead of grinding (or polishing). For the processing of hardened parts, a single process can be used instead of multiple processes, greatly shortening the process flow.

 

Development of superhard tool materials

Superhard tool material refers to natural diamond and artificial diamond and CBN (cubic boron nitride) with similar hardness and properties. As the price of natural diamond is relatively high, so the production mostly adopts artificial polycrystalline diamond (PCD), polycrystalline cubic boron nitride (PCBN), and their composite materials.

As early as the 1950s, the United States used artificial diamond micropowder and artificial CBN micropowder under high temperature, high pressure, catalyst and binder sintering into large size polycrystalline blocks as tool materials. It has since been developed by DeBeers in South Africa, the former Soviet Union and Japan. In the early 1970s, the composite sheet of diamond or CBN and hard alloy was introduced. They are made by sintering or pressing a layer of PCD or PCBN of 0.5mm ~ 1mm on the hard alloy matrix, which solves the problems such as low bending strength of super hard cutting tool materials, insert welding difficulties, so that the application of super hard cutting tools has entered the practical stage. At present, there are synthetic large single crystal diamond, and functional materials such as diamond film coating and thick diamond film produced by CVD (chemical vapor deposition), which greatly expand the application field of superhard tool materials.

The research and application of superhard tool materials began in 1970's, and the manufacturer of superhard material and its products was built in Guiyang in 1970. In the whole 20 years from 1970 to 1990, the annual output of superhard material only increases from 460,000 carats to 35 million carats. In the 1990s, many superhard material production plants introduced complete sets of superhard material synthesis equipment and technology from foreign countries, and output has developed rapidly. By 1997 the annual output of synthetic diamond in our country has reached about 500 million carats and CBN output amounts to 8 million grams.

 

Properties of superhard tool materials

Diamond has high hardness and wear resistance, and its microhardness can reach 10000HV. It is a hard material among tool materials. At the same time, its coefficient of friction is small, no affinity with non-iron metal, chip flow is easy, high thermal conductivity, not easy to produce chip tumor when cutting, processing surface quality is good. It can effectively process non-ferrous metal materials and non-metallic materials, such as copper, aluminum and other non-ferrous metals and their alloys, ceramics, sintered hard alloy, various fiber and particle reinforced composite materials, plastics, rubber, graphite, glass and various wear-resistant wood (especially solid wood and plywood composite materials).