On processing of Inconel718 through multi-channel discharge ablation

This paper presents a new method of multi-channel discharge ablation to improve the electrical discharge machining (EDM) ablation efficiency of superalloy Inconel718 and enhance the post-ablation surface quality of the superalloy. First, a multi-channel discharge ablation processing system was constructed. Second, the multichannel discharge characteristics were studied through the discharge waveforms, and multi-channel discharge was found to improve processing efficiency, reduce workpiece surface roughness, diminish surface micro-cracks, and decrease recast layer thickness. Finally, multi-channel discharge ablation experiments with Inconel718 were performed. Results show that the material removal rate (MRR) of multi-channel discharge ablation processing of Inconel718 increased with an increase of oxygen content in the aerosol dielectric. As the electrode eccentricity increased, the MRR of multi-channel discharge ablation first increased and then maintained a constant value. Under the same discharge parameters, the MRR of multi-channel discharge ablation using a copper electrode was 6.8 % lower than that of the brass electrode, and the electrode relative wear rate (ERWR) of the copper electrode was 72 % lower than that of the brass electrode. The MRR of the copper electrode is therefore comparable to that of the brass electrode, but the ERWR of the copper electrode is much lower than that of brass.