Experimental Investigation on Surface and Machining Characteristics of Micro ED Milling of Ti-6Al-4 V with Different Nano Powder Mixed Dielectrics

Abstract

Micro ED milling is a micro machining technique for machining of high-quality micro parts on the electrically conductive material. Achieving a good surface finish with higher material removal is difficult in Micro ED (μED) Milling due to the short circuits and arcing attributed to partial removal of debris. In this research work, an attempt has been made to improve the quality of machined surfaces in the milling process without compromising the machining characteristics using nano powder mixed dielectrics such as Silicon carbide (SiC) and Carbon nano tubes (CNT). The milling trails were carried out using Tungsten carbide (WC) electrodes under adopted levels of powder concentration and discharge energy region in order to determine the best condition for achieving maximum material removal and excellent surface finish. Further, the morphology of the machined surface was examined using Scanning Electron Microscope (SEM) and found that ridges, crater size and overlapping of craters were considerably reduced due to addition of nano powders in dielectric resulted in high surface finish. The micro cracks are larger with higher discharge energy for all dielectrics used, whereas it is significantly reduced with nano powder mixed dielectrics as compared to plain dielectric. CNT powder offered high MRR and the minimum EWR as compared to other dielectrics used. Both the CNT and SiC powder mixed dielectrics have marginally improved the surface hardness. Results indicated that the electrical conductivity of dielectric has a significant effect on machining and surface characteristics. The surface texture achieved with CNT mixed dielectric looks better than that of other dielectrics: especially with the higher order of powder concentration of 0.9 g/l. Milling trails were designed using full factorial design for plain and nano powder mixed dielectrics.