Diamond tools have excellent adaptability in the processing of non-ferrous metals and wear-resistant materials. Among the tool materials, diamond is the hardest. Under suitable processing conditions, diamond has a longer service life than high speed steel, cemented carbide, ceramic, and polycrystalline cubic boron nitride. It also has the disadvantage that it is generally not suitable for the processing of ferrous materials. But in high-speed, high-volume production, diamonds are often the most effective tool for processing materials such as aluminum and graphite.
When using a diamond tool, the user has two options:
One is polycrystalline diamond (PCD) and the other is newer chemical vapor deposition (CVD) diamond.
(1)Polycrystalline Diamond (PCD)
Polycrystalline diamond (PCD) has the hardness, strength and abrasion resistance of natural diamond, but there is no sensitivity of natural diamond to breakage. It is polymerized from synthetic diamond particles under high temperature and high pressure. During the process, the polycrystalline particles are simultaneously bonded to a solid carbide substrate to improve mechanical strength and impact resistance. PCD is very suitable for high-speed cutting of aluminum, especially suitable for achieving good surface roughness. Occasionally, it also exhibits excellent performance when processing highly abrasion resistant materials.
In general, PCD is recommended for cutting high-silicon aluminum alloys and also for the processing of brass, copper, bronze and carbide. The processes used include car, boring, profiling, grooving, milling and hole machining. Due to the chemical interaction between diamond and iron, PCD is generally not suitable for processing ferrous materials. But it can deal with the processing of bimetallic materials, including the combination of aluminum and cast iron.
Another benefit of PCD is that the existing range is available to meet the needs of any non-ferrous metal processing. In general, fine-grained diamond is used in applications where the wear resistance of the material to be processed is low and the surface roughness is very high; medium-grain diamond is generally used as a general grade for machining; coarse-grained diamond is used for roughing and is particularly resistant to abrasion. Material, but the surface roughness is not high.
(2)Chemical Vapor Deposition (CVD) Diamond
CVD diamond is suitable for almost all non-ferrous metals. Good results are being achieved in the interrupted cutting of high silicon aluminum alloys and in the processing of pre-sintered cemented carbide, brass, copper and carbon fiber materials.
CVD diamond also has a lower coefficient of friction. Both cemented carbide and PCD bond the workpiece material, while CVD diamond is not sticky. At the same time, the low coefficient of friction also allows CVD diamond tools to withstand large cutting loads, making cutting faster and more efficient.
CVD diamond exhibits thermal and chemical stability in use.
CVD diamond also has good lubricity and thermal conductivity, giving it a key advantage in high speed and dry cutting.
The last advantage of CVD diamond is that it maintains high hardness and wear resistance even at high cutting temperatures.
The main advantage of CVD diamond compared to PCD is the quality of the cutting edge. Although CVD is also polycrystalline, it does not contain a cobalt binder and is pure diamond, so the cutting edge is continuous. This allows for a higher cutting speed and better surface roughness because the tool does not heat up. He also firmly believes that built-up edge does not pose a problem for CVD diamond. According to Norton, the thermal conductivity of CVD diamond is 50% higher than that of PCD. The reason is that the CVD blade is a monolithic diamond that can be used to conduct heat immediately. The thermal conduction of the PCD blade passes through the cobalt-diamond composite, and the thermal conductivity is worse.
