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Machining of aluminum/SiC composites using CVD coated diamond cutting tools

High silicon aluminum engine block

High silicon aluminum engine block

Cutting tools for high silicon aluminum engine block

Silicon aluminum composite material is a rigid particle reinforced metal matrix composite material, because it has the advantages of high specific strength and stiffness, low linear expansion coefficient, good dimensional stability, good wear resistance and heat resistance, good remelting ability and low price, it is suitable for the production of wear-resistant, heat resistance, high strength, light weight parts (such as engine piston, vehicle brake, etc.). Therefore, it has great application potential in aviation, aerospace, automobiles, motorcycles, instruments, weapons and other industrial fields. Due to the addition of high strength hard and brittle SiC ceramic particles in the material, the mechanical properties of the matrix material are greatly improved, and the macro-isotropy of the composite material is also shown. But at the same time, it also brings great difficulties to the cutting machine, making the cutting tool wear quicker when cutting SiCp/Al composite materials, machining accuracy and surface quality is difficult to ensure. Research shows that the effect of using high-speed steel and carbide cutting tools to machine such materials is not good, and the wear is very quick. The tool fails in a short time.

 

CVD diamond coating tool is a tool made of an extremely thin (50µm) diamond film deposited on the carbide, ceramic and other tool material substrate by ChemicAlVapor Deposition (CVD) method. Diamond has excellent thermodynamic properties of single crystal diamond (such as very high hardness, high thermal conductivity, low friction coefficient and low expansion coefficient, etc.), so CVD diamond film coated tools also have high wear resistance and good toughness. It has become one of the preferred tools for machining non-ferrous metals and their alloys, non-metallic hard and brittle materials, high silicon aluminum, high wear resistant materials and other difficult materials.

 

When machining SiCp/Al composites with CVD diamond coating tool, the selection of cutting parameters is closely related to the wear of the tool relief. The higher the cutting speed vc, the larger the cutting depth ap, and the smaller the feed rate f, the greater the wear value of the tool relief. This is consistent with the law of CVD tool machining of traditional materials.

When machining SiCp/Al composite materials with CVD diamond coating tools, the higher the content of SiCp in the workpiece material and the coarser the particle size, the worse the cutting performance of the workpiece material and the greater the wear of the tool.

When the negative rake angle (-8° ~ -11°) of the appropriate size is used for machining SiCp/Al composite materials with CVD diamond coating tool, the wear resistance of the tool is better than that of the tool with zero rake angle and positive rake angle.

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