Influence of polarity on the performance of Blasting Erosion Arc Machining

Blasting Erosion Arc Machining (BEAM) is proposed to achieve high-efficiency machining for difficult-to-cut materials such as high-temperature alloys. By creatively controlling the arc plasma with the mechanism named hydrodynamic arc breaking, BEAM can remove bulk material with a high material removal rate (MRR). However, the BEAM generated surface is rough and requires additional post processing. In order to improve the resulting surface quality, positive electrode polarity BEAM was performed by using graphite bundled electrode to machine AISI D2 steel workpiece in this study. Experimental results demonstrate that compared with negative electrode BEAM, machining with positive polarity achieves a better surface quality with less MRR and high relative tool wear ratio (TWR). The explanation of the differences can be attributed to the performance of arc plasma resulting from the variation of the flushing velocity in the discharge gap. Therefore, it is possible to machine with high efficiency and a better control of the profile and surface quality of the workpiece by combining negative and positive (N-P) BEAM processes together. (C) 2015 CIRP.