Experimental study on the ultraprecision ductile machinability of single-crystal Germanium

Jiwang Yan, Kouki Maekawa, Jun'ichi Tamaki, Akihiko Kubo

Research output: Contribution to journalArticlepeer-review

70 Citations (Scopus)


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 60 nm 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.

Original languageEnglish
Pages (from-to)29-36
Number of pages8
JournalJSME International Journal, Series C: Mechanical Systems, Machine Elements and Manufacturing
Issue number1
Publication statusPublished - 2004 Mar
Externally publishedYes


  • Brittle ductile transition
  • Cutting
  • Diamond turning
  • Ductile regime machining
  • Germanium
  • Machinability
  • Optical component
  • Single crystal
  • Ultraprecision machining

ASJC Scopus subject areas

  • Mechanical Engineering
  • Industrial and Manufacturing Engineering


Dive into the research topics of 'Experimental study on the ultraprecision ductile machinability of single-crystal Germanium'. Together they form a unique fingerprint.

Cite this