Ultra-Precision Machining of Brittle Optical Materials in the Nanometer Range of the Cut Layer Thickness

The traditional technology of machining brittle optical materials includes initial grinding of the surfaces by diamond wheels with various granulometric compositions in a strict sequence from course to fine fractions. The surfaces are further subjected to chemomechanical polishing with classified flours (loose abrasive). This technology has significant drawbacks such as relatively low efficiency and stability of the process, complex automation and control, and the effect of the polisher’s skills on the quality of machining. At the Russian Research and Development Tooling Institute VNIIINSTRUMENT and Bauman Moscow State Technical University, technological research and design developments aimed at improving the performance, accuracy and quality of machining of brittle optical materials are performed within the framework of the Agreement on the Federal Target Program. The research is based on the hypothesis of quasi-plasticity of brittle materials. The analysis of the experimental data has shown that when the material is cut at nanometric thicknesses, the surface layer of the brittle material changes into the quasi-plastic state; the surface is formed without chips and cracks, with roughness within a few nanometers.

References

[1] Bifano T., Dow T., Scattergood R. Ductile-regime grinding: a new technology for machining brittle materials. Journal of engineering for industry, 1991, vol. 113, no. 2, pp. 184–189.

[2] Teplova T.B. Kvaziplastichnoe udalenie poverkhnostnogo sloia tverdykh khrupkikh materialov s polucheniem nanometrovogo rel’efa poverkhnosti [The method of quasi-plastic grinding of a solid brittle material intended for getting a surface with nanometeric relief rougness]. Nauchnyi vestnik MGGU [Scientific Bulletin MSMU]. 2010, no. 8, pp. 73–88.

[3] Nazwa T. Precision surface grinding of silicon carbide with fine grain diamond cup wheel. Engineering e-Transaction, 2010, vol. 5, no. 1, pp. 19–26.

[4] Sheinman E. Plastichnoe rezanie khrupkikh materialov v nanodiapazone. Obzor zarubezhnykh issledovanii [Plastic cutting brittle materials at the nanoscale. Review of Foreign Studies]. Instrumenty. Tekhnologiia. Oborudovanie [Tools. Technology. Equipment]. 2007, no. 12, pp. 54–56.

[5] Shavva M.A., Lapshin V.V., Grubyy S.V. Processing of brittle materials in the nanometer range of thickness of layers cut. IOP Conf. Series: Materials Science and Engineering, 2015, vol. 91, no. 1, pp. 12062–12068, doi:10.1088/1757-899X/91/1/012062.

[6] Goel S., Luo X., Comley P., Reuben R.L., Cox A. Brittle-ductile transition during diamond turning of single crystal silicon carbide. International journal of machine tool and manufacture, 2013, no. 65, pp. 15–21.

[7] Shavva M.A., Grubyy S.V. Cutting Forces Calculation at Diamond Grinding Of Brittle Materials. Applied Mechanics and Materials, 2015, vol. 770, pp. 163–168. Doi: 10.4028/www.scientific.net/AMM.770.163.

[8] Shariff Udin M., Seah K.H.W., Li X.P., Rahman M., Liu K. Effect of crystallographic orientation on wear of diamond tools for nano-scale ductile cutting of silicon. Elsivier, 2004, pp. 751–759.

[9] Prasad Pawase, Brahmankar P.K., Pawade R.S., Balasubramanium R. Analysis of Machining Mechanism in Diamond Turning of Germanium Lenses. Procedia Materials Science, 2014, no. 5, pp. 2363–2368.

[10] Wang J., Fang F., Zhang X. An experimental study of cutting performance on monocrystalline germanium after ion implantation. Precision Engineering, 2015, no. 39, pp. 220–223.

[11] Grubyi S.V., Lapshin V.V. Modelirovanie protsessa i razrabotka tekhnologii sverkhtochnoi obrabotki ploskikh otrazhatelei odnoreztsovoi almaznoi frezernoi golovkoi [Process modeling and ultra-precision machining technology development for flat reflectors using a diamond milling head]. Nauka i obrazovanie. MGTU im. N.E. Baumana [Science and Education. Bauman MSTU]. 2014, no. 2. Available at: http://technomag.edu.ru/doc/699743.html, doi: 10.7463/0214.0699743.

[12] Evans J., Rhorer L. Fabrication of optics by diamond turning. Chapter 41 in Handbook of Optics, 2nd, II, 1995.

[13] Chen H., Dai Y., Zheng Z., Gao H., Li X. Effect of crystallographic orientation on cutting forces and surface finish in ductile cutting of KDP crystals. Machining Science and Technology, 2011, vol. 15, no. 2, pp. 231–242.

[14] Shavva M.A., Grubyi S.V, Analiz vzaimosviazi iznosa kruga i sil rezaniia pri almaznom shlifovanii [Analysing a Relationship between Wheel Wear and Cutting Forces during Diamond Grinding]. Nauka i obrazovanie. MGTU im. N.E. Baumana [Science and Education. Bauman MSTU]. 2014, no. 11. Available at: http://technomag.bmstu.ru/doc/731997.html, doi: 10.7463/1114.0731997.