Abstract: A novel high-efficiency arc discharge machining process named blasting erosion arc machining (BEAM) based on hydrodynamic arc-breaking mechanism is proposed and implemented. It substantially differs from electrical discharge machining (EDM). This technology composes of several key elements, such as high density energy input carried by arcing, multi-hole electrode with three-dimensional contour, high velocity flow field in the discharge gap, and multi-axis feed control. The BEAM is capable of machining 3D complex part with high material removal rate. The machining experiments are conducted with graphite bundled electrode as a tool, and typical difficult-to-cut material GH4169 (similar to Inconel718) as a workpiece. The maximum material removal rate (MRR) reaches 14 000 mm3/min, and the minimum relative tool wear ratio (TWR) is less than 1 % while the peak discharge current is 500 A. Meanwhile, the hardness of machined surface is lower than that of matrix and the thickness of heat affected zone and recast layer are less than 100 μm. These imply that the subsequent semi-finishing process such as cutting could be applied easily. Therefore, the machining characteristics of BEAM demonstrate that it is a promising technology to deal with bulk removal roughing of difficult-to-cut materials.

Key words: blasting erosion arc machining, hydrodynamic arc breaking mechanism, material removal rate, relative tool wear ratio