2. Elliptical vibration cutting processFigure 1 shows a schematic illustration of the elliptical vibration cutting process.The diamond tool is fed at a nominal cutting speed, and the tool tip is generallycontrolled to vibrate elliptically in the plane determined by the nominal cutting directionand the depth of cut direction. In the present study, the nominal cutting speed is set tobe lower than the maximum vibration speed ensuring that the tool is separated from theworkpiece in each vibration cycle.As shown in Fig. 1, in a cycle of the elliptical vibration, the cutting starts from point A,and then the workpiece material is removed in the form of a chip. After the tangent of thetool trajectory becomes parallel to the rake face, the cutting tool separates from the chipat point B. Because of this intermittent process, reduction in the chip thickness andcutting forces can be attained. Due to this separation in each vibration cycle, the cuttingtool and the workpiece can be cooled by the surrounding air and/or the cutting fluid. Thisalso allows suppression of adhesion between the tool and the workpiece. As a result,the thermo-chemical wear is supressed efficiently. Because of these characteristics,ultra-precision machining of hardened steel can be attained, as reported in Brinksmeierand Gläbe (2001). Suzuki et al. (2007) also clarified that ultra-precision machining oftungsten alloy becomes feasible due to the same reason. Kim and Loh (2007) clarifiedthat this process is also advantageous to fabricate micro structures due to small cuttingforce and less burr formation.