Surface burning of high-speed reciprocating wire electrical discharge machining under large cutting energy

In this paper, the cutting surface burning problems of high-speed wire electrical discharge machining (HS-WEDM) under the condition of large energy are investigated, and the causes of the surface burn are analyzed. According to microscopic morphology, element composition of the cutting surface, and analysis of discharge waveform in the processing, the causes of the surface burn are as follows. The working medium between electrodes rapidly vaporizes under the condition of large energy. In addition, discharging lacks a full working medium, which results in failure to remove ablation products and in sintering on the surface of the workpiece. Notably, the surface burning appears to be asymmetric because of gravity. The influences of forward and reverse cutting of HS-WEDM, duty ratio, and wire speed on the surface burn are also analyzed. A method for adjusting forward and reverse duty ratio to improve the surface quality under large energy cutting is introduced. A new mode of variable speed reciprocating wire electrical discharge machining is designed, which can guarantee machining efficiency and can reduce surface burn.