Polycrystalline diamond (PCD) is a new type of superhard material which has been studied and used in the world since 1970s. It is sintered at high temperature of 1400 C and high pressure of 6GPa.
Polycrystalline diamond is not only an engineering material, but also a new functional material. It is not only a high-tech product, but also a high-benefit product. With the development of modern industry and science and technology, polycrystalline diamond has been widely used in modern industry, national defense and high-tech fields because of its excellent mechanical, thermal, chemical, acoustic, optical and electrical properties.
Polycrystalline diamond tools have become an indispensable means in modern cutting. This is mainly reflected in the following aspects:
(1) High speed cutting and high stability processing;
(2) Ultra-precision mirror processing;
(3) Dry cutting and clean processing.
(1) High hardness and wear resistance
The hardness of polycrystalline diamond is about 10000HV, which is the hardest material in the world. It is much higher than that of cemented carbide and engineering ceramics. Because of its high hardness and isotropy, polycrystalline diamond has excellent wear resistance.
(2) Low friction coefficient
The friction coefficient between polycrystalline diamond and some non-ferrous metals is lower than that of other materials, which is about 1/2 of that of cemented carbide. The low friction coefficient not only reduces the deformation and cutting force, but also prevents chip accumulation during cutting, thus reducing the roughness of the machined surface.
(3) High thermal conductivity
Polycrystalline diamond has high thermal conductivity, better than silver and copper, and much higher than general cemented carbide. Therefore, the cutting heat is easy to dissipate in the cutting process, so the cutting temperature is lower.
(4) High machining accuracy
Polycrystalline diamond tools have low thermal expansion coefficient and high modulus of elasticity, so they are not easy to deform in the cutting process. Under the action of cutting force, the tools can maintain their original parameters, keep sharp for a long time, and have high cutting accuracy. So when PCD tool is used to process, cutting force and cutting temperature can be reduced, tool durability and cutting rate can be improved, and good machined surface can be obtained.
Automobile and Aerospace
PCD tools have very high durability (more than ten times longer than cemented carbide tools), stable dimensional processing accuracy and good workpiece surface roughness. The main processing objects are non-ferrous metals, non-metallic materials and woodworking materials, alloys, ceramics containing Al2O3, composite materials reinforced by various fibers and particles, plastics, rubber, graphite, glass, wood, etc., and ultra-precision processing of the above materials can also be done. At present, the main varieties are PCD woodworking saw blades and trimming knives, PCD indexing blades, PCD piston series tools, PCD wheel tool, PCD commutator tool, PCD case, jewelry tool and various PCD welding lathe tools, radium knives.
The application of PCD cutting tools in automobile industry accounts for 60%. PCD cutters are mainly used in the automotive field to process skirts, pinholes, cylinder blocks, gearboxes, carburetors of engine pistons. Because the silicon content of these parts is high (more than 10%) and most of them are produced in large quantities by pipeline mode, the service life of the tools is demanded to be high, so the cemented carbide tools are not competent. The durability of the diamond tools is 10-50 times that of the cemented carbide tools, which can ensure the dimensional stability of the parts and greatly improve the cutting performance. Speed, processing efficiency and surface quality of workpiece.
Wood Processing Industry
At present, the widely used wood-based panels are obviously different from the traditional wood. In a sense, synthetic panels are the concept of synthetic resin, and their processing process is also different from the traditional wood. Especially the development of wood-based panels such as MDF, plywood, particleboard and composite flooring has accelerated the demand for super-hard cutting tools, so that diamond cutting tools have gradually replaced the position of traditional woodworking tools in the market. Among them, Al2O3 on the outermost layer of laminated flooring has a great influence on the wear of cemented carbide tools. PCD tools can effectively solve this problem.