In this study, we performed efficient and high-precision grinding of cemented carbide alloys with a newly developed grinding wheel, and investigated the ground surface characteristics. The processing results showed that final finishing using the Chromium bonding #8000 wheel produced an extremely smooth ground surface roughness Ra of 4 nm. In addition, the Cr-series exhibits strong chemical adhesion because the Cr that penetrated and diffused into the substrate during the machining process has strong chemical affinity with the DLC film.

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There is continuing effort to improve the surface quality and productivity of mechanical components of automobile engines and transmissions. The authors propose a novel grinding process for quickly improving workpiece surface quality. This process, called "Rapid Rotation Grinding (RRG)", accomplishes ultra-high speed grinding with an extremely high work peripheral speed. Simulation study indicated that this process suppresses the increase in workpiece temperature during grinding, and this result was verified in grinding tests of hardened steel. Under a constant speed ratio, the stock removal rate of this grinding process at work peripheral speeds up to 100 m/min is 2.5 times higher than that of conventional grinding, while white layer formation was reduced to less than half. In addition, the residual stress induced in workpieces by this process is compressive rather than tensile, and the workpiece surface roughness can be markedly reduced quickly.

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Increasing the work peripheral speed of the grinding process is expected to reduce the thickness of the heat-affected layer because the heat source moves over the workpiece surface more rapidly. To apply this effect to actual machining processes of mechanical components, rapid rotation grinding tests of hardened steels were performed at an extremely high work peripheral speed. This paper describes the grinding performance obtained under ultra-high speed grinding conditions at a wheel peripheral speed of 200 m/s and at work peripheral speeds up to 500 m/min, which is a higher speed ratio than for conventional grinding. The experimental results indicated that surface roughness differs from that of conventional grinding and remains small after spark-out even if the work peripheral speed is increased. In addition, rapid rotation grinding does not change the microscopic structure of the workpiece material, and residual stress in the workpieces is similar to that before grinding. Rapid rotation grinding produces workpieces free of surface damage.

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A processing method using diamond wire tool have been examined as slicing methods for hard and brittle materials. This study was performed to develop a thin diamond wire tool to reduce the kerf loss. The core wire of the newly developed tool is comprised of a pair of twisted piano wires of φ58μm, with electrodeposition of diamond grains of φ30∼40μm on the surface of the core wire. In this study, the optimal plating conditions to make the thin diamond wire tool were determined under a series of experimental conditions. The slicing characteristics using the thin diamond wire tool and the processing mechanism are also described.

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