Optimizing the contributing electro-erosive discharge parameters for reducing the electrode wear and geometric dimensional deviation in EDM of Ti-based superalloy

Abstract

The low thermal conductivity, the small magnitude of modulus of elasticity, and the high chemical reactivity of Ti-6Al-4V make it difficult to machine this material using traditional processes. The intended requirements for the applications of the said alloy, like in biomedical and aerospace, further complicate its processing. Thereof, electric discharge machining (EDM) opted for this alloy. However, intrinsic issues of EDM, that is, electrode wear rate (EWR) and dimensional overcuts, restricted its utilization. Therefore, the potential of three powder-based additives and dielectric fluids against different electrode materials has been deeply envisaged to address the abovementioned issues. Because the choice of best dielectric has a direct bearing on heat input to the electrode which influences the melting/vaporization of the tool wear of the electrode. It is worth mentioning that these concerns have not been discussed so far in such a broad spectrum. Taguchi’s experimental design is used for experimentation. The results show that transformer oil performance is best rated compared to other dielectrics. Overall, the reduction in tool wear rate and overcut obtained with transformer oil is 21.3% and 21.4%, respectively, in contrast to the other dielectrics. The electrode of Cu outperforms for yielding the smaller value of overcut and tool wear rate. In the case of micro-additives, alumina has proved its potential for lowering the electrode wear rate. Deep and wide craters of a depth of 150 µm have been observed by using the brass electrode in kerosene oil, whereas the small and shallow craters of 38 µm depth have been encountered using the Cu electrode in the presence of transformer oil.