In the process of making diamond cutting tools that we usually use, the materials generally used are natural single crystal diamond, artificial single crystal diamond, chemical vapor deposition (CVD) diamond thick film, artificial polycrystalline diamond composite sheet, etc.
The following Wanlong Diamond Tools will introduce to you, what materials are made of diamond cutting tools?
1. Artificial polycrystalline diamond
Synthetic polycrystalline diamond (PCD) is a polycrystalline material made by polymerizing diamond micropowder and solvent under high temperature and high pressure. Generally, it is made into an overall circular sheet with cemented carbide as the matrix, which is called polycrystalline diamond composite sheet. According to the thickness of the diamond matrix, the composite sheet has different specifications such as 1.6mm, 3.2mm, and 4.8mm. The thickness of polycrystalline diamond is generally about 0.5mm.
At present, the diameter of PCD produced in China has reached 19mm, while the diameter of the largest composite sheet in foreign countries such as GE has reached 58mm, and De Beers has reached 74mm.
According to the needs of making tools, it can be cut into different sizes and angles by laser or wire cutting to make turning tools, boring tools, milling tools, etc.
The hardness of PCD is lower than that of natural diamond (about HV6000), but the bending strength is much higher than that of natural diamond. In addition, by adjusting the particle size and concentration of diamond powder, the mechanical and physical properties of PCD products are changed to adapt to different materials and different processing The needs of the environment provide tool users with a variety of options.
PCD tools have much higher impact and seismic performance than natural diamond. Compared with cemented carbide, the hardness is 3-4 times higher; the wear resistance and life are 50-100 times higher; the cutting speed can be increased by 5-20 times ; Roughness can reach Ra0.05. High cutting efficiency and stable machining accuracy.
PCD, like natural diamond, is not suitable for processing steel and cast iron. This tool is mainly used for processing non-ferrous metals and non-metallic materials, such as: aluminum, copper, zinc, gold, silver, platinum and their alloys, as well as ceramics, carbon fiber, Rubber, plastic, etc. Another major function of PCD is to process wood and stone.
PCD tools are particularly suitable for processing high-silicon aluminum alloys, so they have been widely used in the automotive, aerospace, electronics, and shipbuilding industries.
2. Natural single crystal diamond
Natural single crystal diamond is an anisotropic single crystal. It has a hardness of HV9000-10000, which is the hardest substance in nature. This material has excellent wear resistance and can maintain dimensional stability for a long time during cutting. Therefore, there is a long tool life.
The cutting edge of natural diamond knives can be processed to be extremely sharp. It can be used to make ophthalmic and neurosurgery scalpels; it can be used to process the curved surface of contact lenses; it can be used to cut light guide glass fibers; it can be used to process gold and platinum jewelry patterns; the most important use is It lies in high-speed super-finishing of non-ferrous metals and their alloys, such as aluminum, gold, babbitt alloy, beryllium copper, red copper, etc.
The ultra-precision machining tool made of natural diamond has no defects in the arc part of the tool tip under a 400x microscope. It is used to process aluminum alloy polyhedral mirrors, oxygen-free copper laser mirrors, gyroscopes, video recorder drums, etc. The performance is rough. The degree can reach Ra (0.01-0.025).
The toughness of natural diamond material is very poor, the bending strength is very low, only (0.2-0.5) Gpa. The thermal stability is poor, and the hardness will be lost when the temperature reaches 700℃-800℃. No matter how high the temperature is, it will be carbonized. In addition, it is different from Iron has a strong affinity and is generally not suitable for processing steel.
3. Artificial single crystal diamond
Artificial single crystal diamond is used as a tool material, and there is currently an industrial grade single crystal diamond material produced by De Beers (DE-BEERS) that can be bought on the market. This material is slightly inferior to natural diamond in hardness. Other properties are not the same as natural diamond. Comparable. Due to manual manufacturing, its cleavage direction and size have become controllable and uniform.
With the development of high temperature and high pressure technology, the maximum size of artificial single crystal diamond can be 8mm. Because this material has relatively good consistency and low price, it has received widespread attention. As a new material to replace natural diamond , The application of artificial single crystal diamond will have a big development.
4. CVD diamond film
CVD diamond thick film is a diamond material made by chemical vapor deposition. As a tool material, its hardness is higher than PCD. Because it does not contain a metal bond, it has high thermal conductivity and high temperature oxidation resistance. However, the current production The toughness of CVD material is relatively poor, it cannot be cut by wire cutting, and its use is subject to certain restrictions.
Because there is no directionality of cutting and grinding, the process of grinding is poor, and it is extremely difficult to grind the sharp edge like natural diamond and synthetic single crystal diamond. The use of cutting tools is still in the experimental stage, and further research and development are needed.
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Its interesting to know that PCD tooling have much higher impact and seismic performance than natural diamond. I was watching a documentary about a automotive factory last night and I’ve seen them use some diamond cutting tools. The tools they used seems to be quite strong and convenient so I think they’re really great.