Study of surface integrity and machining performance during main/rough cut and trim/finish cut mode of WEDM on Ti–6Al–4V: effects of wire material

Abstract

Due to increased demand of dimensional accuracy and high precision of manufactured parts, wire electrical discharge machining (WEDM) became very popular, especially for ‘difficult-to-cut’ materials like titanium alloys. Grade 5 Ti alloy (Ti–6Al–4V) has enormous application in aerospace and biomedical fields. WEDM performance of Ti–6Al–4V is somewhat restricted due to its poor thermal conductivity, formation of hard and brittle carbide-/oxide-rich layer and often surface cracking which affect fatigue performance of the part product. Therefore, multi-cut strategy is adapted to mitigate machining-induced defects. The multi-cut mode consists of one main/rough cut followed by a number of trim/finish cuts. Aspects of surface integrity of the WEDMed Ti–6Al–4V obtained in different modes of cut are delineated in this reporting. Three slots are produced: (1) main cut; (2) main cut followed by one trim cut; and (3) main cut followed by two trim cuts using uncoated brass wire and zinc-coated brass wire, respectively. Surface morphology along with topographical features including roughness average, crack density, recast layer thickness, material immigration, residual stress and micro-indentation hardness is studied. Results obtained thereof are analysed with relevance to kerf width, material removal rate and wire wear.