2004 Volume 47 Issue 1 Pages 29-36
Single-crystal germanium is an important infrared optical material. In the present work, single-point diamond turning experiments on single-crystal germanium (100), (110) and (111) planes were conducted in order to examine their ultraprecision machining characteristics. Three kinds of surface textures and chip morphologies were observed during the brittle-ductile transition of the machining mode. The brittle-ductile boundary changed significantly with the crystal orientations of the workpieces. Due to the crystallographic anisotropy, micro-fractures were generated on the workpiece surface in a radial pattern from the rotation center. However, it was possible to produce completely ductile-cut surfaces on all crystal orientations by using undeformed chip thicknesses smaller than a critical value, namely, the minimum critical undeformed chip thickness, which was approximately 60nm under the present conditions. Compared to wet cutting, dry cutting was beneficial for ductile machining on a few specific crystal orientations. The findings in this study provide criterions for determining process parameters for the fabrication of aspherical and diffraction infrared optics using single-crystal germanium.
JSME international journal. Ser. 1, Solid mechanics, strength of materials
JSME international journal. Ser. A, Mechanics and material engineering
JSME international journal. Ser. 3, Vibration, control engineering, engineering for industry
JSME international journal. Ser. C, Dynamics, control, robotics, design and manufacturing
JSME International Journal Series A Solid Mechanics and Material Engineering
JSME International Journal Series B Fluids and Thermal Engineering