Polycrystalline diamond (PCD) has been widely used for various cutting tools and die components making use of its hardness and wear resistance properties. The polishing method of single diamond substrate and PCD using ultraviolet irradiation was newly developed to obtain mirror-finished surfaces. Due to the long polishing time in this method, a better pre-machined surface is required to shorten the total processing time. In this study, constant-pressure dry grinding of PCD was performed using a cup type metal-bonded diamond wheel and a constant pressure unit. The grinding was conducted by the dry grinding method and the mist grinding method. These experiments indicated that the dry grinding was more suitable than mist grinding. In addition, it was shown that the flat parts of grains with the same protrusion height on a diamond wheel could produce a good quality grinding surface in the constant-pressure dry grinding of PCD.

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This study was performed to investigate the generation process of crack in gallium arsenide (GaAs) in the grinding process. Scratching experiments of GaAs performed on a previously developed scratching machine with a tilt stage indicated that the crack generation process of GaAs is strongly dependent on the crystal orientation and is different from that of silicon. In the present study, indentation tests were performed to investigate the crack generation process. The results indicated that crack generation differed due to the crystal orientation, and median cracks were observed in the <100> directions. A large number of lateral and median cracks were generated in the [011] and [0-1-1] directions rather than the [0-11] and [01-1] directions. In addition, larger brittle fractures occurred due to the interaction of the stress field when the indentation areas were closed. These results indicated that the depth of cut and distance between indentation areas are important factors to prevent brittle fractures.

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Composite materials are expected to be effective for use in mechanical and structural parts, such as airplane parts. Carbon Fiber Reinforced Plastics (CFRP) are frequently used. When CFRP are used for mechanical structural parts, the need to slice or drill them is inevitable; an abrasive machining method by OD-blade has been widely used to slice them. However, one drawback of the OD-blade slicing method is low tool life due to the hardness of carbon fiber. This study was performed to establish and examine the practical applicability of the vibratory OD-blade slicing method to slice composite materials, such as CFRP. This paper presents the results of experiments regarding slicing accuracy and tool life.

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Estimation of mechanism of surface finish improvement in helical scan grinding, a method in which good surface finish is obtained while retaining high grinding efficiency, was performed based on a virtual grinding trace using a 3D-CAD model. In three grit models, (a) a single grit on a wheel, (b) plural grits arrangement on a helical line along a wheel circumference, and (c) multiple grit arrangement in a triangular pattern, virtual grinding traces and their unevenness or surface roughness were investigated. The virtual grinding trace in helical scan grinding was made by interference of grit trajectories, and the results of the analysis were very similar to experimental results.

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