Ultra-precision cutting is an important field of ultra-precision machining, which is a wide range new technology. The use of precision single crystal diamond tool machining nonferrous metal and non-metal, can directly cut the ultra-smooth machining surface, which can replace the ultra-precision grinding and other finishing processes, greatly improve the processing efficiency, but also can ensure the processing accuracy and machining surface quality. In recent years, single crystal diamond tool has been deeply adopted into all fields of machining, playing an increasingly important role. CVD single crystal diamond is an ideal tool material because of its high hardness and good wear resistance, but at the same time, it brings great difficulties to grind CVD single crystal diamond tools.
Characteristics of Grinding CVD Single Crystal Diamond Tool
In ultra-precision machining, the two basic precision factors of CVD single crystal diamond tool are the edge contour precision and the blunt circle radius of the edge. The roundness of the arc cutting edge for machining aspheric lens is less than 0.05μm, and the straightness of the cutting edge for machining polyhedral mirror is 0.02μm. The blunt radius (ρ value) of the cutting edge indicates the sharpness of the cutting edge. In order to meet various processing requirements, the radius of the cutting edge ranges from 20nm to 1μm.
CVD diamond is anisotropic, so not only the hardness and wear resistance of each crystal face are different, but also the wear resistance of the same crystal face is different in different directions. If the crystal direction is not selected properly, even if the crystal face is selected correctly, the grinding efficiency will be greatly reduced. At the same time, because the compressive strength of diamond crystal is 5 ~ 7 times greater than the tensile strength, the easy grinding direction of crystal face should be selected in the process of grinding, and the edge should face the positive direction of the linear velocity of grinding wheel (i.e. reverse grinding), so as to ensure the grinding efficiency and reduce the degree of micro cleavage of the edge.
The grinding of CVD diamond tool includes rough grinding and fine grinding. The easy grinding direction of crystal should be selected in rough grinding. Rough grinding of diamond tools is related to grinding direction, grinding speed and pressure, and the grit size of diamond powder used. MORESUPERHARD has been committed to providing solutions for ultra-precision tool grinding for many years. Last year, we broke through the problems of PCD tool super-precision grinding and MCD single crystal tool rough grinding and fine grinding. Through continuous attempts and customer communication experiments, this year, we have also reached a new level in CVD single crystal tool grinding. Moresuperhard "916" series grinding wheels for coarse-grinding single crystal tool and the 3000# and 4000# fine grinding wheels for CVD which are currently in production not only provide the strict cutting edge quality but also greatly improve the production efficiency. Compared with the cast iron disc grinding that we have been always using, it not only improves the efficiency, but also shortens the grinding time and reduces the processing cost. Welcome to test and give valuable advice for the development of single crystal tool grinding.
