As a superhard tool material, diamond has been used in cutting for a long time. People use high-pressure synthesis technology to synthesize PCD, which solves the problem of scarcity and high price of natural diamond, and expands the application scope of PCD tools to aviation, aerospace, automotive, electronics, stone and other fields.
Diamond tools have the characteristics of high hardness, high compressive strength, good thermal conductivity and wear resistance, and can achieve high processing accuracy and processing efficiency by high-speed cutting. The properties of diamond tools are determined by the diamond crystal state. In diamond crystal, the four valence electrons of carbon atoms form bonds in a tetrahedral structure, and each carbon atom forms covalent bonds with four adjacent atoms to form a diamond structure. The structure has strong directionality of binding force, so that the diamond has very high hardness.
Due to the fine-grained diamond sintered body of polycrystalline diamond (PCD) with different structural orientations, its hardness and wear resistance are still lower than those of single-crystal diamond despite the addition of binders. However, since the PCD sintered body is isotropic, it is not easy to crack along a single cleavage plane.
Developed countries have carried out research on PCD cutting tools earlier, and its application has been relatively mature.
Since the synthetic diamond was first synthesized in Sweden in 1953, a lot of achievements have been made in the research on the cutting performance of PCD cutting tools, and the application scope and usage of PCD tools have expanded rapidly.
At present, the world's leading manufacturers of synthetic diamond composite sheets mainly include DeBeers of the United Kingdom, GE of the United States, and Sumitomo Electric Co., Ltd. of Japan.
According to reports, in the first quarter of 1995, the output of PCD cutting tools in Japan alone reached 107,000. The application range of PCD cutting tools has expanded from initial turning to drilling and milling.
A survey on superhard tools conducted by a Japanese organization shows that the main considerations for people choosing PCD cutting tools are based on the advantages of surface accuracy, dimensional accuracy and tool life after PCD tools are processed. The synthesis technology of diamond compacts has also been greatly developed. DeBeers has launched a polycrystalline diamond compact with a diameter of 74mm and a layer thickness of 0.3mm.
China's PCD tool market is also expanding with the development of tool technology. The application of PCD cutting tool has also further promoted the research on its design and manufacturing technology. Through the analysis of the application of PCD cutting tools in recent years, it can be seen that PCD tools are mainly used in the following two aspects:
1. Difficult-to-process non-ferrous metal materials
When using ordinary tools to process difficult-to-machine non-ferrous metal materials, defects such as easy tool wear and low processing efficiency often occur, while PCD cutting tools can show good processing performance. For example, the use of PCD cutting tools can effectively process a new type of engine piston material - hypereutectic silicon aluminum alloy (a breakthrough has been made in the research on the processing mechanism of this material).
2. Difficult to process non-metallic materials
PCD cutting tools are ideal for machining difficult-to-machine non-metallic materials such as stone, hard carbon, carbon fiber reinforced plastic (CFRP), and man-made panels.
At present, we know that the processing range of PCD cutting tools has expanded from traditional metal cutting to stone processing MyCIMT, wood processing, metal matrix composites, glass, engineering ceramics and other materials processing. This is a super hard tool material, and it is hoped that it will be used more and more widely.
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