Experimental investigation on the recast layer and performance indicators during nano powder mixed μED miling of Ti-6Al-4V

Abstract

Micro ED milling is an excellent microfabrication technique for machining of complex micro shapes and microstructures. It has the potential to machine any electrically conductive material irrespective of its mechanical characteristics. In this work, the effect of different nanopowders, namely graphite (Gr) and carbon nano tubes (CNT) powder and their concentration on response indicators while machining of Ti-6Al-4V under different discharge energy regions is investigated. The surface texture of the milled surface with plain dielectric and nanopowder mixed dielectrics have also analyzed. The highest MRR was achieved with CNT powder as compared to graphite powder due to its high electrical conductivity. The mixing of nanopowder particles in dielectric resulted in a smoother surface than plain dielectric due to the uniform distribution of heat energy over the machining region. It was found the thickness of the recast layer is reduced due to the addition of nanopowders in the dielectric fluid. The maximium recast layer thickness (4.14 μm) is observed with the plain dielectric at high discharge energy. The thickness of the recast layer seems to be minimium when higher-order powder concentration is used. Nanopowder mixed dielectrics offered a better material removal rate than plain dielectric at the cost of overcutting. Material migration is lesser in the case of nanopowder mixed dielectrics due to an increase in number of discharges per second. The material migration is reduced by 54% and 31%, due to the addition of CNT and Gr powders in dielectric respectively. Tool life gets improved with nanopowders mixed dielectric due to the reduction of unwanted discharges and embdement of powder particles on tool material.