Common knowledge of diamond tools.
Before selecting and using diamond coating tools, users must understand the following common knowledge about diamond coating tools:
(1) the difference between CVD diamond coating and amorphous diamond coating.
Amorphous diamond (also known as diamond-like carbon) coating is a carbon film deposited by PVD process. It has the SP3 bond of some diamond and the SP2 bond of some carbon. The film has a high hardness, but it is lower than the hardness of diamond film. The thickness is also thinner than the diamond film we usually deposited. When processing graphite, the life of amorphous diamond coating tool is 2-3 times that of uncoated cemented carbide tool. Compared with CVD diamond is the pure diamond coating using CVD process, the processing of graphite when the knives' service life 12 to 20 times that of carbide cutting tools, which can decrease The Times of change and improve the reliability of machining precision and consistency.
(2) it is not possible to process hardened steel with diamond tools.
Diamond is made up of carbon atoms. When some materials are heated, carbon atoms are sucked out of the diamond and carbon is formed in the workpiece. Iron is one of these materials. When using diamond tools to process iron materials, the heat generated by friction can cause the carbon atoms in the diamond to spread to the iron, thus causing the diamond coating to be invalidated in advance due to chemical wear.
(3) limitation of diamond tools.
Heavy grinding and (or) coating hard to ensure the quality of diamond coated tools generated due to the tool surface coating for pure diamond, so with diamond grinding wheel for cutting tool resharpening takes a long time. In addition, the tool used for the growth of diamond. The preparation process will change the chemical properties of the tool surface. As the coating requires very precise control of this chemical property, the effect of the tool re-coating is difficult to be guaranteed.
(4) the life of diamond coated knives is different.
As with any other tool, diamond coated tools have different life spans, depending on the cutting material, the feed rate and the cutting speed, and the geometry of the workpiece. In general, the life of diamond coated tools for processing graphite is 10 to 20 times that of uncoated cemented carbide, and may even be longer in some cases. In this way, a tool can be used to complete almost any machining task without changing the knife due to tool wear, avoiding the process interruption and recalibration, thus it is possible to realize unattended processing. In the processing of composite materials, it is also possible to obtain longer tool life. It is reported that diamond coated tools can live up to 70 times as long as uncoated carbide cutting tools in processing high-density fiberglass, carbon fiber and gl0-fr4.
(5) problems existing in diamond tools.
Diamond coating peeling coating can prevent spalling is a serious problem of diamond coated tools, also is a common problem, especially in processing such as carbon fiber material), can lead to unpredictable the knives' service life. In the late 1990s, the interface chemistry was identified as an important factor affecting the adhesion properties of diamond coatings. By selecting good carbide chemical compatibility features, adopt appropriate pretreatment technology and reasonable deposition reaction conditions, it is possible to reduce or eliminate the diamond coating peeling, steady smooth implementation of the wear mode. Under the microscope, the diamond coated tool with normal wear is observed, and the diamond can be found to be stable and wear down to the carbide substrate without breaking or peeling.
