Fabrication and Characterization of Helical Grooved Cylindrical Electrodes Generated by WED Turning Process

Abstract

Electric discharge drilling (EDD) process has got worldwide attention in the manufacturing industries owing to its unique electro–thermo-erosion mechanism capable of creating precise microholes on any conductive materials, irrespective of its hardness. The thrust of the research activities in this area is to address the challenges and explore the possibilities of EDD in the machining of high aspect ratio holes in turbine blades, fuel injectors, nozzles of inkjet printers, microchemical reactors, and biomedical devices. The motivation of the present work is to develop a new machining strategy by altering the electrode surface in order to enhance the flushing rate, which will eventually result in the accomplishment of better quality and high aspect ratio holes. Hence in the present work, the electrodes used for the EDD process are modified by creating a helical groove using wire electric discharge turning process (WEDT). Further analysis of the geometry of micro helical grooves machined on cylindrical electrodes has been carried out for the first time. The best geometry of helical groove was obtained at a pulse on time of 30 µs, pulse off time 186 µs, and depth of cut of 150 µm with a helix angle of 34.12° and pitch of 2.22 mm. Extracting the surface characteristics of the micro helical grooves is very difficult, an attempt has been made to quantify the surface roughness, the best surface is obtained has 12.27 μm Ra. The proposed electrode has the potential to replace the existing EDM electrodes as it is superior in terms of flushing and hence machining of good quality microholes.