Jet electrochemical machining of multi-grooves by using tube electrodes in a row

Jet electrochemical machining (JEM) is a promising way to generate grooves in difficult-to-machine materials. The electrolyte flow distribution in multi-grooves machining is quite different from that of a single groove. If the tubes are too close together, the reflected electrolyte jets interfere with each other, which will seriously affect the multi-grooves critical performances such as machining accuracy and stray corrosion upon the non-processing areas. This paper proposes using tube electrodes in a row (TER) with reasonable tube interval to lessen undesirable machining affects from the electrolyte flow interference and insulation coatings to reduce stray corrosion in the non-processing regions. It was observed that in multi-grooves machining, electrolyte baffles and plenty of droplets generate due to intensive electrolyte flow interference, and the electrolyte droplets gradually slid toward the tube tip and eventually fall onto the anodic surface as intermittent stray current passages when TER without coatings was used in JEM, which lead to stray corrosion in the non-machining zones. Simulations and experiments showed that when the tube sides were insulated, the current density distribution on the surfaces between adjacent grooves declined drastically, and stray corrosion reduced in the undesirable areas. Moreover, it was found that when the tubes were too close to each other, the electrolyte droplets from flow interference drop faster, thereby deteriorating the current stability and multi-grooves edges. Thus, a tube interval exceeding 3.00 mm was found to be acceptable for JEM with TER. Based on these findings, by using TER with a tube interval of 4.00 mm, both denser crisscross and parallel grooves with groove interval of 2.00 mm and rare stray corrosion were fabricated in a large-area surface (28 mm x 45 mm) by planning the tool path properly. Also, multi-grooves with different groove depths were produced simultaneously at one time on the workpiece merely by setting different inter-electrode gaps for each component tube in the TER.