Title: Analysis of heat affected zone in the micro-electric discharge machining

Authors: Olivier Thao, Suhas S. Joshi

Addresses: Department of Mechanical Engineering Indian Institute of Technology, Bombay, Mumbai 400 076, India. ' Department of Mechanical Engineering Indian Institute of Technology, Bombay, Mumbai 400 076, India

Abstract: It is known from the classical EDM process, which is a thermal process, that a significantly damaged zone, called Heat Affected Zone (HAZ) is generated around the EDmachined features. However, the presence of the analogous zone in the micro-EDM process has not been addressed adequately so far. This paper therefore reports experimental investigation into such zone, HAZ around the micro-EDmachined microholes. The work involved microhardness measurement, Scanning Electron (SE) and Electron Backscatter Diffraction (EBSD) microscopy and Energy Dispersive X-ray (EDX) analysis along the longitudinal cross sections of the micro-EDmachined microholes. It was evident that there is a definite presence of HAZ around the micro-EDmachined holes wherein there is a reduction in the microhardness, which could be a function of variation in the material erosion phenomenon prevailing along the length of microholes and the metallurgical changes due to annealing of bulk material around holes. SE and EBDS microscopy did not show evidence of any recast layer ahead of the HAZ on micro-EDmachined surfaces.

Keywords: electric discharge machining; EDM; micro EDM; heat affected zone; HAZ; microhardness; surface damage; electro-discharge machining; microholes.

DOI: 10.1504/IJMTM.2008.016771

International Journal of Manufacturing Technology and Management, 2008 Vol.13 No.2/3/4, pp.201 - 213

Published online: 22 Jan 2008 *

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