Experimental study on accuracy and surface quality of TC2 in LS-WEDM multiple cuts

Abstract

Low-speed wire electrical discharge machining (LS-WEDM) is an effective alternative to manufacture intricate shapes with high accuracy in difficult-to-machine materials like TC2 (Ti–3Al–1.5Mn). This paper aims to study the dimensional accuracy and surface quality of TC2 workpiece machined by LS-WEDM based on multiple cuts including rough and trim cuts. First, an orthogonal experiment L16 (54) is designed to evaluate the main influencing factors on surface roughness and machining time. Second, the optimum parametric settings for multiple cuts are designed, and the experimental work has demonstrated that the acute angle convex corners machined by LS-WEDM are accompanied with bending angles and the bending direction is opposite to the wire electrode movement, but the obtuse angle does not appear this phenomenon. Moreover, the wire deflection model based on the unilateral discharge mechanism is built to improve the machining accuracy. In addition, by comparing with the kerf and the surface microstructure of rough and trim cuts, the kerf consistency is improved obviously; the craters, cracks, voids and spherical droplets are gradually becoming much smaller size; the 3D surface parameters including Sa, Sq, Sy and Sz are greatly decreased. Eventually, the elongated craters and the overlapping convex peaks are discovered on TC2 workpiece surface.