Before selecting and using a diamond-coated tool, the user must know the following common sense about the diamond-coated tool:
(1) the difference between CVD diamond coating and amorphous diamond coating
Amorphous diamond (also known as diamond-like carbon) is a carbon film deposited using a PVD process. It has a part of the diamond SP3 key, but also has a part of the carbon SP2 button; its film hardness is high, but lower than the hardness of diamond film; its thickness is also more than we usually deposited thinner diamond film. Processing graphite, the life of amorphous diamond coating tool is not coated coated carbide cutting tool 2-3 times. In contrast, CVD diamond is the use of CVD process deposition of pure diamond coating, processing of graphite when the tool life is 12-20 times the carbide cutting tool, which can reduce the number of tool changes, improve the reliability and accuracy of processing consistency.
(2) can not be used diamond processing hardened steel
Diamond consists of carbon atoms. When some materials are heated, they draw carbon atoms from the diamond and form carbides in the workpiece. Iron is one of these materials. With diamond tools to process iron material, the heat generated by the friction will make the carbon atoms in the diamond diffuse into the iron, resulting in diamond coating due to chemical wear and premature failure.
(3) restrictions on diamond tools
Grinding and / or re-coating of diamond-coated tool quality is difficult to ensure that the surface of the tool surface is pure diamond, so it takes a long time to recompen the tool with a diamond wheel. In addition, the tool used to make the diamond grow. The preparation process will change the chemical properties of the tool surface, because the coating requirements of the chemical properties of the very precise control, so the effect of re-coating tool is difficult to be guaranteed.
(4) diamond coating tool life is different
As with any other tool, the life of the diamond-coated tool varies, depending on the material being cut, the feedrate selected and the cutting speed, and the geometry of the workpiece. In general, the life of diamond-coated diamond tools is 10-20 times that of uncoated carbide cutting tools, and in some cases may even be longer. In this way, you can use a tool to complete almost any processing tasks, without tool wear and tool change, to avoid the processing of interruption and re-calibration, which may achieve unattended processing. In the processing of composite materials, it is also possible to obtain a longer tool life.
It is reported that in the processing of high-density glass fiber, carbon fiber and Gl0-FR4 and other difficult to process composite materials, diamond-coated tool life can be up to 70 times the uncoated carbide cutting tools.
(5) Diamond tool problems
The peeling of diamond coatings can prevent coating peeling is a serious problem with diamond-coated tools and is a common problem (especially when processing materials such as carbon fibers) that can cause tool life to be unpredictable. In the late 1990s, the interface chemistry was identified as an important factor affecting the adhesion of diamond coatings. It is possible to reduce or eliminate the peeling of the diamond coating and to achieve a stable wear pattern by selecting the appropriate chemical properties of the cemented carbide, using appropriate pretreatment techniques and reasonable deposition reaction conditions. Under the microscope to observe the normal wear of the diamond coating tool, you can find that the diamond was stably worn until the carbide base, without the occurrence of chipping or peeling.
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