Title: A comparative study on the performance of sinking and milling micro-EDM for nanofinishing of tungsten carbide

Authors: M.P. Jahan, Y.S. Wong, M. Rahman

Addresses: Department of Mechanical Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore. ' Department of Mechanical Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore. ' Department of Mechanical Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore

Abstract: Micro-electrical discharge machining (micro-EDM) is a flexible machining technique offering the possibility to produce freeform microstructures and micromoulds using hard-but-conductive materials like tungsten carbide (WC). It is desirable to obtain fine surface finish directly using micro-EDM when micromoulds and dies are machined, so that subsequent polishing can be avoided. This paper presents a comparative study between the performance of die-sinking and milling micro-EDM for the semi-finish and finish machining of WC. The comparison was conducted with respect to achieved material removal rate (MRR), relative electrode wear ratio (EWR), surface topography, average surface roughness (R_a) and peak-to-valley roughness (R_max). It has been found that, micro-EDM milling is capable of generating smooth, shiny and defect-free surfaces with lower R_a and R_max at comparatively higher MRR and lower EWR in the finish micro-EDM of WC. Moreover, the MRR in milling micro-EDM can further be increased at semi-finishing regime with the sacrifice of surface finish and EWR by increasing the electrode scanning speed. Comparing all the performance parameters, milling micro-EDM has been found to be the better option for semi-finishing and finishing of WC than die-sinking.

Keywords: nanofinishing; tungsten carbide; die sinking; micro-EDM; milling; surface topography; average surface roughness; peak-to-valley roughness; material removal rate; MRR; electrode wear ratio; electrical discharge machining; electrco-discharge machining; EDM; microstructure; micromoulds; nanomanufacturing; nanotechnology.

DOI: 10.1504/IJNM.2010.034783

International Journal of Nanomanufacturing, 2010 Vol.6 No.1/2/3/4, pp.190 - 206

Published online: 22 Aug 2010 *

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