Study on blasting erosion arc machining of Ti-6Al-4V alloy

Blasting erosion arc machining (BEAM) was applied to improve the machining efficiency of Ti-6Al-4V alloy. 5-factor, 2-level fractional factorial experiment was firstly employed to find out the main factors for MRR (material removal rate). According to the results of fractional factorial experiment, 3-factor, 2-level full factorial experiment was conducted to find out the relationship between machining performance and the main factors (peak current, pulse duration, and pulse interval) under the negative electrode machining. Results revealed that when peak current was 500 A and pulse duration was 8 ms, MRR could achieve 16,800 mm(3)/min, which means the specific energy efficiency was 33.6 mm(3)/(A center dot min). Then, MRR was optimized base on MATLAB optimization toolbox and could reach 20,100 mm(3)/min when adopting the optimized parameters (peak current 600 A, pulse duration 8.8 ms, and pulse interval 3.0 ms). Although TWR (tool wear ratio) can be effected by the machining parameters, it appeared to be stable (around 3 +/- 1 %). Besides, the polarity effect was also studied, and flow field simulations were employed to illustrate the influence of feeding direction on the surface roughness. In addition, the machined surface was analyzed by utilizing SEM, EDS, XRD, etc. Results of the surface analysis disclosed that the oxygen content in the negative electrode machined surface was obviously higher than that in the positive electrode machined surface. Since the positive electrode machined surface was much smoother, it can be used to improve the surface quality while the negative electrode machining is suitable for the bulk material removal with high energy. Finally, a Ti-6Al-4V turbine blade sample was machined to demonstrate the feasibility of high efficiency BEAM in difficult-to-cut material processing.