Title: Use of solid lubricants like graphite and MoS₂ to improve grinding of Ti-6Al-4V alloy

Authors: A.K. Sahoo; S.K. Soni; P.V. Rao; S. Ghosh

Addresses: Department of Mechanical Engineering, Indian Institute of Technology, Delhi, New Delhi-16, India. ' Department of Mechanical Engineering, Indian Institute of Technology, Delhi, New Delhi-16, India. ' Department of Mechanical Engineering, Indian Institute of Technology, Delhi, New Delhi-16, India. ' Department of Mechanical Engineering, Indian Institute of Technology, Delhi, New Delhi-16, India

Abstract: Grindability of Ti-6Al-4V alloy is not good due to its chemical reactivity at elevated temperatures and its low thermal conductivity. In grinding process most of the specific energy consumed converts into heat energy which raises the grinding zone temperature. As Ti-6Al-4V alloy's thermal conductivity is not good, heat accumulation takes place mostly on the ground surface and sub surface. Consequently, due to this increased surface temperature Ti-alloy's reactivity increases which leads to rapid tool wear and more redeposition of work material on the ground surface. The heat generated at the grinding zone is due to shearing, ploughing and rubbing. The ploughing and rubbing phenomenon increases the energy loss mainly due to friction. In order to reduce the frictional losses suitable solid lubricants can be used. In this research work, graphite and MoS₂ were used as solid lubricants and for proper delivery of the lubricants to the grinding zone a suitable solid lubricant supplying unit was also developed. Grinding was done using vitrified SiC grinding wheel. It was observed that the use of both these lubricants substantially reduced the grinding forces. The reductions in forces were in between 5% and 20% compared to dry grinding. However, it was found that amongst the two lubricants used, MoS₂ gave better results.

Keywords: titanium alloys; SiC grinding wheels; silicon carbide; graphite; MoS2; molybdenum disulphide; solid lubricants; grindability; energy loss; friction; grinding forces; lubrication.

DOI: 10.1504/IJMMM.2012.050428

International Journal of Machining and Machinability of Materials, 2012 Vol.12 No.4, pp.297 - 307

Received: 29 Jan 2011
Accepted: 09 May 2011
Published online: 23 Aug 2014 *

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