Machining investigation on Ti-6Al-4V alloy using a wire electrical discharge hybrid turning (WEDHT) process

Abstract

Wire electrical discharge hybrid turning (WEDHT), is a new unconventional material removal process to machine electrically conductive difficult-to-cut materials. WEDHT uses the complex material removal mechanism to remove the material by a series of intermittent sparks generated at the machining interface. This material removal on both surfaces of workpiece and wire affects the machining responses such as surface roughness (SR), material removal rate (MRR), depth of recast layer and micro-hardness. This also results in the formation of oxide layers at the machined surface. In this work, the WEDHT experiments are conducted on Ti-6Al-4V Grade 5 alloy to analyze the effect of the above set of responses on the machined surface. Pulse ON time (TON), wire feed rate (fw) and workpiece rotational speed (Ss) are varied at three levels. The cause and effect of outputs and the optimal combination of input parameters are analyzed. At the optimal level, 27% improvement in the surface finish and 51% improvement in the material removal rate are obtained. The recast layer, crater, and debris formed on the machined surface were analyzed using a scanning electron microscope (SEM). Vicker’s micro-hardness tester is used for measuring the variation of micro-hardness. The presence of oxide layers on the surface is quantified using x-ray diffraction analyzer (XRD) and energy dispersive x-ray spectroscopy (EDS) analyzer.