This paper describes the development of an ultraprecision micro-EDM machine, which has a rotating spindle for forming an electrode on the EDM machine. When the room temperature changes by 3°C, the Z-axis of this machine moves in 0.5-nm steps using fine positioning and motioning and thermal displacement control. It was shown that, when the machining method combining EDMing and grinding with use of the same PCD tool on the same machine was applied to processing of micro holes (d=φ50μm), the hole diameter accuracy of the top and bottom surfaces on tungsten carbide (t=100μm) was 0.2μm. The surface roughness of inner hole was also improved.

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This report proposes a new constant-pressure magnetic abrasive finishing process to improve the workpiece form accuracy for precision machining of planar and curved workpieces, based on the machining principle of an internal magnetic field-assisted machining process using a magnetic machining jig. This new machining method is a process by which a constant pressure is applied to the magnetic pole of a conventional magnetic brush, and the constant pressure acts on the surface of the workpiece through the magnetic particle brush formed at the magnetic pole surface. Experiments were performed using the conventional magnetic abrasive finishing process and the newly proposed constant pressure magnetic abrasive finishing process to compare the deburring characteristics. A brass disk in which was drilled a hole was used as a workpiece. The results showed that burrs can be removed using this new plane magnetic abrasive finishing process, and this process is more useful than the conventional magnetic brush for improving the form accuracy of the workpiece.

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When producing grooves in quartz glass using an ultrafine-grit resin-bonded diamond blade, it is possible to simultaneously increase both the densification and the height alignment of the cutting edges using the grain burial phenomenon and the grain attritious wear phenomenon. After producing grooves with this diamond blade, the workpieces were polished at an angle and the average depth of the cracks in their groove floors was investigated. Grinding with five times the average depth as the finishing margin produced a bottom surface roughness of 23 nm (Ra). At a feed rate as low as 2 mm/min, fine square grooves with a bottom surface roughness of 21 nm (Ra) and a side surface roughness of 7 nm (Ra) could be obtained without finish machining.

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Grinding with a fine abrasive wheel has problems with regard to vulnerability to loading and marked reduction of the dressing interval as the chip pocket is extremely small. In this report, the authors propose a new coolant supply method that combines the "kilosonic vibration coolant," which superimposes a kHz-order ultrasonic vibration with the "coolant flow guided flexible sheet method," which is as effective coolant supplying method, to achieve active reduction of loading. With application of this method to surface plunge grinding of copper and SKD11 using a GC1000 grinding wheel, it was shown experimentally that wheel wear accompanying adhesion of chips could be reduced. In addition, it was also confirmed that a good surface could be produced by miller face grinding on SCM435 using a GC3000 grinding wheel.

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Zirconia has some excellent characteristics as a dental material. For practical use, precise processing of the Zirconia is necessary. However, since grinding wheel and workpiece are both small and thin in dental applications, to prevent any damage it is essential to reduce the grinding force. In this study, ultrasonic-assisted grinding, as a machining method, is used to reduce grinding force and it is applied to micro-grinding of Zirconia. An ultrasonic-assisted grinding model is proposed and decreasing mechanism of the grinding force is clarified. Authenticity of the model is then verified experimentally. Moreover, the model of surface roughness improvement of this technique is discussed.

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