Experimental Investigation on Improvement of Machinability of SS 304 Through Multipass Cutting in WEDM

Wire electric discharge machining (WEDM) is a famous machining process for manufacturing intricate and 3D complex geometries on tough difficult-to-machine superalloys and composites. Stainless steel 304 (SS 304) alloy has excellent corrosion resistance and forming faces which is used in aerospace, chemical, petrochemical industries, etc. The present work focuses on WEDM of SS 304 using a brass wire electrode of ϕ 0.25 mm with rough cut trailed by trim cuts to improve the machinability. WEDM experiments were conducted as per Taguchi’s L9 experimental design with four-factor and three-level. The effect of pulse on time (Ton), pulse off time (Toff), current and wire offset during trim cuts on machinability characteristics, namely surface roughness, material removal rate (MRR), kerf width and microhardness, was analysed. Experimental results showed that trim cuts with varying wire offsets produced better surface finish, high MRR with hardness, and low kerf width compared with rough cut. Furthermore, surface characteristics of rough cut with trim cut surfaces were analysed using scanning electron microscope (SEM) images. Finally, grey relational analysis (GRA) was used to find the optimal input parameter combination and simultaneously optimize the selected machinability responses.