Improvement of the machining characteristics in WEDM based on specific discharge energy and magnetic field–assisted method

Abstract

This paper is aimed at investigating and improving material removal rate (MRR) and surface quality in wire electrical discharge machining (WEDM) based on specific discharge energy and magnetic-assisted method. A set of a single-factor experiment is implemented to analyze the effects of carbon content and discharge parameters on machining characteristics. The concept of specific discharge energy (SDE) is proposed to reveal the fundamental influence of workpiece material properties on material removal rate and to obtain the optimal machining feed rate. The mathematical model between SDE and the physical properties of workpiece material is also fitted out. Additionally, it can be found that, in subsurface material, the recast layer is with the maximal hardness followed by bulk material and heat-affected zone. Ra and RLT firstly increase and then decrease with the increase of carbon content, and they have a positive correlation with discharge peak current and pulse-on time. Finally, verified experiment shows that, comparing with other machining feed rates, the method of optimal machining feed rate according to SDE can simultaneously achieve the fastest actual machining speed and the lowest surface roughness. In addition, the method of magnetic-assisted trim cutting can almost eliminate recast layer and reduce heat-affected zone to less than 20 μm.