EDM is an effective method for deep and narrow slot machining. The high aspect ratio blind slot can be machined with jump motion and vibration assistance. The decrease in machining accuracy and actual depth caused by electrode consumption in this process are currently common problems. Using oil-based working fluids, graphite electrodes have different wear and deposition patterns under different conditions. This study aims to control the final geometric accuracy of deep and narrow slot machining by optimizing electrical parameters. Experiments using orthogonal design were conducted with a 20×1×20mm narrow slot. The combined influences of parameters on the electrode geometry evolution are concluded. The peak current and duty factor are the main factors affecting the pattern of electrode tip geometry. Experiments were carried out to analyse the wear pattern corresponding to different levels of these two factors. The locations where deposition and wear are prone to occur are found to be the edge of the electrode tip. Parameters combinations capable of stably maintaining the shape of the electrode end are found. The results showed the feasibility of adjusting the tip wear pattern. Thus the final geometric precision of the slot machining can be controlled by adopting apposite parameters.
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