Usually people attribute metal matrix composite materials as "difficult-to-machine materials". In fact, they form short chips during processing, and the matrix is generally aluminum alloy. The cutting temperature is low, so the machinability is very good; the main reason is that the particles added in it are reinforced The hardness of the material is very high, such as the hardness of SiC is as high as 3000-3500HV. The hard particles are distributed in the matrix, and like the abrasive particles in the grinding wheel, they will scrape and impact the cutting edge of the tool, causing the cutting edge to wear quickly. The higher the hardness of the hard particles, the larger the size of the particles, and the more the number of particles, the faster the tool wear. As a result, machining with conventional carbide tools is difficult and the tool life is low or not usable at all.
Japanese scholars have used cemented carbide tools (brand K10) to turn A390 hypereutectic silicon-aluminum alloy and cast iron with a silicon content of 16%-18%. It fails due to severe abrasive wear, and its life is less than 1/3 of that of cutting cast iron. Replacing the cut material with a SiC whisker reinforced aluminum alloy results in tool wear much faster than cutting high-silicon aluminum alloys. Such as machining with coated carbide tools, the hard particles in the composite material will still wear through the coating quickly and rapidly expand into the carbide matrix and cause the tool to fail. Diamond is the hardest known substance in the world, and its actual use has proved that it is the best tool material for machining metal matrix composites. Using diamond to process metal matrix composite materials, the cutting speed can reach 800~1000m/min, the tool life can be several times or even dozens of times higher than that of cemented carbide, and the surface roughness value is small, which can reach Ra0.025-0.012µm . This is because diamond not only has high hardness (up to 10000HV), good wear resistance, and can maintain a sharp cutting edge for a long time, the edge roughness value is small, and the friction coefficient is low, good adhesion resistance, high thermal conductivity, cutting It is not easy to stick to the tool and generate built-up edge, so the surface quality of the machine is far better than other tools.