Some common sense before choosing and using diamond tools

Before selecting and using diamond-coated tools, users must understand the following common sense about diamond-coated tools:
The difference between coatings
Amorphous diamond (also known as diamond-like carbon - annotation) coating is a carbon film deposited using the PVD process. It has both the SP3 bonds of diamond and the SP2 bonds of carbon; its film hardness is very high, but lower than the hardness of diamond films; its thickness is also thinner than the diamond films we usually deposit. When processing graphite, the life of amorphous diamond-coated tools is 2-3 times that of uncoated carbide tools. In contrast, CVD diamond is a pure diamond coating deposited using the CVD process. The tool life when processing graphite is 12-20 times that of carbide tools, which can reduce the number of tool changes and improve the reliability and accuracy of processing. consistency.
Machining hardened steel
Diamond is made of carbon atoms. When certain materials are heated, they pull carbon atoms out of the diamond and form carbides in the workpiece. Iron is one such material. When diamond tools are used to process iron group materials, the heat generated by friction will cause the carbon atoms in the diamond to diffuse into the iron, causing the diamond coating to fail prematurely due to chemical wear.
Tool limitations
The quality of regrinded and/or recoated diamond-coated tools is difficult to guarantee. Since the coating generated on the surface of the tool is pure diamond, regrinding the tool with a diamond grinding wheel takes a long time. In addition, the tools used to grow diamond. The preparation process will change the chemical properties of the tool surface. Since coating requires very precise control of this chemical property, the effect of recoating the tool is difficult to guarantee.
Tool life
Like any other tool, the life of a diamond-coated tool varies and depends primarily on the material being cut, the feed rate and cutting speed chosen, and the geometry of the workpiece. Generally speaking, the life of diamond-coated tools for machining graphite is 10-20 times longer than that of uncoated carbide tools, and in some cases may even be longer. In this way, almost any machining task can be completed with one tool without the need to change tools due to tool wear, avoiding processing interruptions and recalibration, making unattended machining possible. In the processing of composite materials, it is also entirely possible to obtain longer tool life.
It is reported that when processing difficult-to-machine composite materials such as high-density glass fiber, carbon fiber and Gl0-FR4, the life of diamond-coated tools can be up to 70 times that of uncoated carbide tools.
Problems
Diamond coating peeling can be prevented Coating peeling is a serious problem with diamond-coated tools and a common problem (especially when machining materials like carbon fiber), which can lead to unpredictable tool life. In the late 1990s, interfacial chemistry was identified as an important factor affecting the adhesion properties of diamond coatings. By selecting compatible cemented carbide chemistries, using appropriate pretreatment techniques and reasonable deposition reaction conditions, it is possible to reduce or eliminate diamond coating spalling and achieve a smooth wear pattern reliably. When observing a normally worn diamond-coated tool under a microscope, it can be found that the diamond is steadily worn down to the carbide matrix without chipping or spalling.