Experimental study on micro EDM-drilling of Ti6Al4V using helical electrode

Abstract

There is a growing interest in the machining of micro-holes with high aspect-ratio in difficult-to-machine alloys for the aerospace industry. Processes based on electro discharge machining (EDM) and developed for the manufacture of both micro-electrode and micro-hole are actually used, but most of them involve micro-EDM machines. In this work, the influence of EDM parameters on material removal rate, electrode wear, machining time and micro-hole quality when machining Ti6Al4V is studied. Due to an inefficient removal of debris when increasing hole depth, a new strategy based on the use of helical-shaped electrodes has been proposed. The influence of helix angle and flute depth with respect to process performance has been addressed. Main results include 37% reduction in machining times (hole diameter 800μm) when using electrode helix angle of 45° and flute-depth of 50μm, and an additional 19% with flute-depth of 150μm. Holes of 661μm diameter and as much as 6.81mm depth, which yields in aspect ratio of 10:1, have successfully been machined in Ti6Al4V.