Generation of microfeatures on stainless steel by electrochemical micromachining

Abstract

Micromachining technologies are becoming prominent for the fabrication and growth of microproducts like microchip, switches, printed circuit board, micro-sensors, chemical micro-reactors, and micro-fluidic systems like air lubricated bearing etc. Electrochemical micromachining (EMM) is an important micromachining technology due to specific advantages like no tool wear, absence of stress, no heat-affected zone, high MRR, bright surface finish, and ability to machine complex shapes regardless of hardness. Microfeatures were generated on SS-304 stainless steel by EMM. Major difficulties in sharp and accurate microfeature generation is the localization of current during machining and consequently, the overcut and taper formation in vertical wall. To reduce overcut and taper angle of microfeatures, machining zone was simulated with a conical micro tool of taper angle 13° and normalized current density along the cross-section of microchannel was calculated from the distribution of equipotential lines. The maximum current density was found at the exit side of the microchannel and from this simulated data it was predicted that taperless slot generation was possible with conical micro tool. Later on, it was verified by practical experiments for the generation of through, taper-less microfeatures. This paper aims at reducing taper angle, overcut, corner deviation of microfeatures like microchannels, bands of microprofiles etc. The experimental study of process parameters such as pulse frequency of applied voltage, micro tool feed rate, electrolyte concentration, and depth of sinking by micro tool were conducted for the investigation and analysis of their effects on material dissolution. Finally, it has been shown that both conical and straight micro tool can be used for generation of taperless microslots. After the proper selection of process parameters, microfeatures were machined.