Face cutting and single point fly cutting (SPFC) of tungsten carbide were conducted using two monocrystalline diamond tools and three polycrystalline diamond tools to investigate the wear characteristics in terms of the diamond structure and composition. A negative rake angle of 30° was shown to provide the minimum tool wear. The wear of monocrystalline diamond cutting tools depends on the crystal planes that form the rake face and the flank face of the cutting tool, and cleavage fracture occurs when the cutting force acts as a shear force on the (111) crystal plane. Binderless nano-polycrystalline diamond tools show excellent wear resistance beyond those of PCD tools and CVD polycrystalline diamond tools in cutting as well as better wear resistance than monocrystalline diamond tools in face cutting.

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Abrasive jet machining (AJM) of silicon carbide fiber-reinforced silicon carbide ceramic composite (SiC/SiC CMC) was carried out with various sizes of silicon carbide fine abrasives. A microindentation experiment was performed to evaluate the mechanism of material removal by particle impact. The results showed that the machine rate was different depending on the particle size and that interface fracture (debonding) influenced the mechanism of material removal. The relationship between structure scale of the SiC/SiC CMC and the impact media size is discussed.

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Amorphous NiP plate is used as a mold for precision optical parts due to its superior machinability. Pores of about 100 μm in diameter are occasionally generated in the amorphous NiP plate. At present, amorphous NiP plates with pores are rejected. However, because the mold sizes have become large in recent years, the possibility of pores has also become high. In addition, the cost of amorphous NiP plate has also become high. Therefore, methods for repairing the pores in amorphous NiP plate should be developed. In this paper, laser-assisted powder jet deposition is proposed as a method for repairing amorphous NiP plate. In addition, fundamental experiments were carried out.

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CFRP components usually require trimming and drilling. Less frequently, they require cutting. Tool wear and detachment of the rear surface of CFRP plates occur during the process of drilling or cutting. In this study, CFRP plates were ground with a grain-arranged diamond wheel and a GC wheel, and the grinding performances of the wheels were compared. The diamond wheel showed superior finishing capability of CFRP to the GC wheel. However, when the orientation of carbon fibers was parallel to the cutting direction of the diamond grains, detachment of the fibers occurred frequently. When the fiber direction was rotated by 30° – 90° in the horizontal plane, the detachment was effectively reduced. To enhance the finishing capability of the diamond wheel, smaller grains with sharp cutting edges are required.

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