Eco-Friendly ECM in citric Acid electrolyte with microwire and microfoil Electrodes

Abstract

In this research, eco-friendly electrochemical machining (ECM) characteristics for drilling and milling stainless steel using microwire and microfoil electrodes in citric acid electrolyte are investigated. According to cell configuration and applied pulse conditions, extraordinary phenomena such as tool electrode cut-off due to Joule heating followed by fractured tool welding to the work substrate, electrolyte capillary action around the tool electrode, and tool shaking by evolved bubbles are observed and their effects on micro ECM performances are discussed. Complex micro/nano textures were found on the inner wall of the drilled holes under strict pulse conditions and their generation mechanism is described. Metal structure formed on the bottom of the blind hole under weak electric conditions hinders further drilling. By adjusting electrochemical conditions, micro holes, 37 μm in diameter with 100 μm depth and 26 μm in diameter with 50 μm depth, are drilled using a 10 μm thick tungsten wire electrode. A complex micro hand pattern is fabricated by electrochemical milling on SS 304 substrate. Furthermore, high quality micro grooves with dimension of 34 μm wide and 17 μm deep are machined using 20 μm thick stainless steel foil electrode. Finally, micro electrochemical reverse drilling technique is newly suggested and its effectiveness on machining time reduction is validated.