PCD tools can be used in the precision machining of non-metallic hard and brittle materials such as graphite, high wear-resistant materials, composite materials, high si-Al alloy, and other tough non-ferrous metal materials. There are many types of diamond cutting tools with significant differences in performance. The structure, preparation methods, and application fields of different types of diamond cutting tools are quite different.
The thermochemical wear state of PCD tools varies greatly according to the type of materials to be processed. The worn state of the tip after the end surface turning of the oxygen-free copper and pure aluminum with the super precision diamond turning tool with the linear cutting edge of 130° on the ultra-precision lathe indicates that the front surface of the cutting tool with the oxygen-free copper has the crescent depression wear, but the cutting edge edges still remain sharp. When cutting pure aluminum, the cutting edge becomes an arc edge, but no crescent depression is found on the front edge. The different wear mechanism can be seen from the difference of these wear states: when cutting copper, the crescent depression of the cutter’s front cutter surface is caused by the oxidation of diamond due to the catalytic action of copper, while the cutting edge edges of the cutter do not produce oxidation wear due to the seamless contact with the workpiece. When cutting aluminum, due to the direct contact between the working surface and the tool surface, the workpiece material is cut by the cutting edge and the cutting edge is worn, but because the direction of wear expansion is opposite to the cutting edge when cutting copper (from the cutting edge to the knife surface), so there will be no crescent depression of the front knife surface.
Due to the different thermo-chemical phenomena of different workpiece materials, the wear state of the tool is also different, so it is necessary to design a reasonable tool front Angle and back Angle according to different kinds of workpiece materials. Ultra-precision diamond tool is one of the key factors to realize ultra-precision machining.
With the continuous extension of the cutting time of diamond tools in the factory, the temperature of the cutting area increases continuously. Because the diamond tools are kept working, when the thermochemical reaction temperature is reached, a new metamorphism layer will be formed on the tool surface. Most of the metamorphic layers are poor strength oxides and carbides, which are formed continuously and disappear with the chip, gradually forming the worn surface. Diamond crystal in the cutting force especially carry alternating pulse load under the action of continuous, one after another after the C atom gain enough energy from the lattice escape, cause the crystal defect, the interatomic force is abate, in under the action of external force between lattice shear and peeling, gradually formed the wear and tear on the level of lattice, after reaching a certain number of lattice planes wear will gradually form the surface of tool wear.