Several types of metal-bonded polycrystalline diamond stones for honing were developed. We compared the honing performance of these polycrystalline diamond stones with a monocrystalline diamond stone commonly used in honing of fine ceramics. We found that polycrystalline diamond grains on the stone surface fractured finely during the honing process, and also that the honing force decreased as the grain fractured. In addition, the honing ratio increased using the polycrystalline diamond stone because there was less wear on the stone in comparison to other types of honing stone. The roughness of the honed surface with the polycrystalline diamond stone was the same as that honed by the monocrystalline diamond stone.

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A method for generation of micro shafts of diameter less than 1 mm by turning operation is discussed. Thrust forces occurring in turning operations create difficulty in generating micro shafts of the required geometrical accuracy. In this study, keeping the thrust force at zero in the turning operation was considered to allow micro shaft generation without the problems associated with such forces. An appropriate method for setting the approach angle is proposed, as this is one of the parameters that affect thrust forces; tool nose radii, approach angle, and depth of cut were all controlled. The experimental results indicated that thrust force can be kept at zero, and consequently micro shafts 0.05 mm in diameter and 3.5 mm length could be machined in turning operation.

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This paper describes the development of an electroplated diamond wheel with longer tool life in the helical boring process of fine ceramics. The states of interference between the wheel end and workpiece were estimated by 3D-CAD. Moreover, force distributions of abrasive cutting edges on the wheel end were analyzed using grinding forces monitored during the process. The results indicated that conventional wheels with flat or ball-shaped end profiles cut with abrasive cutting edges on the wheel end. On the other hand, the wheels with spheroid ends proposed here have longer tool life, twice or more that of convention wheels, because the abrasive cutting edges on the wheel end effectively.

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The cutting width is decided by laser power output, cutting speed, focal length, and thermal reaction of materials. In general, a laser beam with a given spot diameter does not cut with exactly the same width as the spot diameter. However, the difference in spot diameter corresponds to the difference in kerf width. The spot diameters induced by the theoretical calculation and the width of cut achieved by experiment were compared. Under certain conditions, the spot diameters corresponded to the width of cut in the experiment. With several differences in cutting width, the behaviors of gas-flow in the kerf were investigated using computer simulations. A fast gas-flow rate in the kerf was shown to facilitate high-speed cutting. Based on these calculations, the influence of cutting width on high-speed cutting was clarified.

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