Research on machining Ti6Al4V by high-speed electric arc milling with breaking arcs via mechanical-hydrodynamic coupling forces

Abstract

A sustainable and advanced manufacturing method named high-speed electric arc milling (H-SEAM) was presented in this research to solve the problems where of environmental pollution and low machining efficiency for difficult-to-cut materials in the traditional electrical discharge machining (EDM)EDM process. This method can achieve high material removal efficiency with arc breaking via a coupling of mechanical and hydrodynamic forces in H-SEAM. Firstly, the material removal mechanisms of H-SEAM and theoretical arc breaking conditions are analysed. Then, comparative experiments on machining titanium alloy Ti6Al4V by different arc breaking methods are conducted to study the material removal rate (MRR), tool electrode wear rate, and machined surface quality of the workpiece. Our experiment results showed that the MRR can reach 780 mm3/min when using a mechanical-hydrodynamic coupling method to break arcs, which is almost five times and nearly twice that when using independent mechanical or hydrodynamic methods to break arcs. Moreover, experimental results showed the machined grooves via mechanical-hydrodynamic coupling forces to break arcs in H-SEAM exhibited higher dimensional accuracy, lower tool electrode wear, lower surface roughness, thinner recast layers, and smaller heat-affected areas than those in arc breaking by independent mechanical or hydrodynamic methods. This can be attributed to the higher removal efficiency of molten metal material and the uniform distribution of energy when using mechanical-hydrodynamic coupling forces to break arcs.