Parametric Investigation Into the Fabrication of Disk Microelectrodes by Electrochemical Micromachining

In electrochemical micromachining (EMM) of microfeatures using straight cylindrical microtools, sidewalls of the structure tapers as depth increases. Disk microtool electrodes are used to minimize the taper formation during the machining of microfeatures. At present disk microtool electrodes are fabricated by wire electrical discharge grinding, reverse electro discharge machining (EDM), and microwire electro discharge machining method, which needs separate EDM machine as well as fabricated microtools suffer from thermal defects like microcracks on surface, residual stress, deformation, and needs careful handling. To overcome these limitations, new method is proposed to fabricate disk microtool electrode by EMM. Also the influences of EMM process parameters like applied voltage, pulse frequency, duty ratio, electrolyte concentration on shank diameter, material removal rate, and surface quality are investigated. Disk microtool electrode of disk height 70 μm, disk diameter 175 μm, shank diameter 93 μm, and shank height 815 μm have been fabricated from tungsten microrod of 300 μm diameter by proposed method and used to machine microfeatures like cylindrical hole with reduced taper angle, reverse taper hole, taper free microgroove, and 3D microstructure with plane surfaces on stainless steel by EMM. Effects of disk height on machining accuracy during generation of microhole, in the form of taper angle are also presented in the paper. Proposed method of developing disk electrode by EMM will be very useful for fabricating disk microtool electrodes with different disk diameters, disk heights, shank diameter, and shank height with desired surface quality by controlling various process parameters. Disk microtools with lower disk heights are more effective to generate microfeatures with minimum taper.