Diamond tool materials are divided into single crystal diamond (there are two kinds of natural and artificial, natural single crystal diamond is expensive, some are replaced by artificial single crystal diamond), artificial polycrystalline diamond (PCD) and artificial polycrystalline diamond and cemented carbide composite blade (PCD/CC) and CVD diamond.
1. Single crystal diamond
Single crystal diamond used as a cutting tool must be large particles (mass greater than 0.1g, minimum diameter length not less than 3mm), mainly used in precision and ultra-precision machining applications with high requirements for surface roughness, geometric accuracy and dimensional accuracy.
Natural single crystal diamond is the most wear-resistant material in diamond. It itself has a fine texture, after fine grinding, the blunt circle radius of the cutting edge can be as small as 0.008~0.005μm. However, natural single crystal diamond is more brittle, its crystallization anisotropy, different crystal faces or crystal hardness in different directions of the same crystal plane are different, in the sharpening and use must choose the appropriate direction. Due to the harsh conditions of use, coupled with the limited resources of natural single crystal diamond, the price is very expensive, so most of the production uses PCD, PCD/CC and CVD diamond tools. Intelligent manufacturing Daguan, focusing on the sharing of theoretical knowledge related to the machinery manufacturing industry; Natural single crystal diamond is mainly used in ultra-precision machining of certain non-ferrous metals or in the production of gold jewelry.
Synthetic single crystal diamond size, shape and performance have good consistency, at present due to the increasing maturity of high temperature and high pressure technology, can prepare a certain size of synthetic single crystal diamond, especially in the processing of high wear resistance layered wood board, its performance is better than PCD diamond, will not cause premature passivation of the edge.
2. Artificial polycrystalline diamond (PCD) and artificial polycrystalline diamond and cemented carbide composite blade (PCD/CC)
PCD is at high temperature (about 1800 °C), high pressure (5~6MPa), the use of cobalt and other metal binders to polycrystalline many diamond single crystal powder polycrystalline materials, although its hardness is slightly lower than single crystal diamond, but it is a randomly oriented diamond grain polymerization, isotropic, used as a cutting tool can be arbitrarily oriented sharpening, no need to choose the best cleavage surface as the rake face like natural diamond. In the cutting, the cutting edge is very insensitive to accidental damage, the anti-wear ability is also strong, can maintain a sharp cutting edge for a long time, processing can use a high cutting speed and a large amount of back eating knife (eating deep), the service life is generally higher than WC-based carbide tools 10 ~ 500 times, and because the metal bond in the PCD has conductivity, so that the PCD is easy to cut and form, and the source of raw materials is rich, its price is only a few tenths to a dozen of natural diamond, It has become a high-performance alternative to traditional WC-based carbide tools.
In order to improve the toughness and solderability of the PCD blade, a diamond composite insert (PCD/CC) is formed by sintering or pressing a layer of 0.5~1mm thick PCD on its surface with cemented carbide as the base. PCD/CC can be used to make tools by welding or clamping. Because of its good weldability, easy regrinding and low cost, it is widely used. It should be pointed out that the sharpness of the edge and the quality of the processing surface of PCD and PCD/CC tools are not as good as that of single crystal diamond, and its machinability is poor, the grinding ratio is small, it is difficult to form arbitrarily according to the geometry of the cutting head, and it is not convenient to manufacture products with complex geometry such as indexable inserts and end mills with chip breakers.
