Control of micro-spark and stray-current effect during EMM process

Electrochemical micromachining (EMM) has proved its immense potential to be used as an alternative micromachining technique to machine very complicated profile on electrically conducting, tough and difficult to machine materials. Performance of electrochemical micromachining (EMM) can be enhanced through diminishing micro-sparking and stray-current material removal by proper controlling of predominant machining parameters. Through this paper an endeavour has been made to establish comprehensive mathematical model for correlating the interactive and higher-order influences of various machining parameters on the combine effect of micro-spark and stray-current machining, through response surface methodology (RSM) approach. Validity and correctiveness of the developed mathematical model for analyzing the effects of various process parameters on the micro-spark and stray-current affected zone (MSAZ) is highlighted through different response surface plots. Condition of machined micro-holes is also analyzed through SEM micrographs supported by voltage graph, captured during normal machining process as well as during machining with micro-sparking. Micro-spark and stray-current affected zone can be considerably reduced to as low as 0.0001 mm under proper controlled machining parametric combination of pulse on/off ratio of 2.1618, machining voltage of 2.8347 V, electrolyte concentration of 10 g/l, voltage frequency of 35 Hz and tool vibration frequency as 100 Hz. A suitable combination of these predominant micromachining process parameters can be obtained from the developed mathematical model for achieving any desired level of precision and surface quality of the machined product.