Micro-SACE scanning process with different tool-surface roughness

Abstract

ABSTRACT As a non-traditional machining process, spark assisted chemical engraving (SACE) can machine hard, brittle, and non-conducting materials. The spark discharges on tool-electrode sidewall result in energy loss and overcut edges. A tool electrode covered with an insulating film on its sidewall is usually used to constrain the discharges to the tool-electrode end. However, not only the preparation of the insulating film is cautious and fussy, but also it is easy to split away under the high temperature and pressure action of SACE. In this research, a novel method constraining the micro-SACE discharges to the tool-electrode end was proposed by changing surface roughness of the tool electrode. The special micro-tool electrode with rough end and smooth sidewall was fabricated on-machine. The constraint effect was experimented by observing the distribution of SACE bubbles and discharges around the tool-electrode end, and the optimal parameters were obtained by evaluating the bubble aspect ratio. Furthermore, machining experiments of the micro-SACE scanning process by constraining discharges to tool-electrode end were verified on ZrO2 ceramics as a kind of difficult-to-machine material. Micro-circular grooves without micro cracks were successfully machined by the use of a Φ300 μm tool electrode.