Surface Integrity of 316L Steel Machined Sequentially by Wire EDM and Wire ECM

Abstract

This research investigates the surface properties of 316L stainless steel machined by combining two wire electro manufacturing processes on a single machining platform, i.e., wire EDM roughing and wire ECM finishing. While the former is well known in industry, the latter has not yet seen much industrial use but can improve the surface integrity since it does not generate heat to achieve material removal, avoiding several EDM (semi)finishing passes at reduced sparking energies. With applications in the medical, energy, and aerospace fields, this research focuses on characterizing the machined surfaces with respect to the surface defects and the chemical composition. The studied surface properties include the (sub)surface morphology with respect to micro cracks and heat related damage introduced by wire EDM, and the mechanism of their removal by wire ECM finishing. The chemical composition of the surface is furthermore evaluated to characterize the contamination of the workpiece material by the tool electrode material. The manufactured samples are studied using a profilometer to quantify material removal and the resulting roughness. Metallographic analysis is carried out by optical microscopy and SEM with EDX. Initial results show an average surface roughness below 0.1 µm Ra by applying a wire ECM finishing pass after wire EDM.