Performance improvement of electrochemical micromachining employing pulse width modulation

Electrochemical micromachining (EMM) is leading a promising role in the fabrication of microcomponents which are used in different fields of micro -engineering applications. By reducing the energy of pulse waveform, machining accuracy can be improved, but in stagnant electrolytes, generated sludge during machining which creates an obstacle to further improvement of machining performance. To overcome this problem, pulse width modulation (PWM) technique is employed in EMM, where pulse width moves from shortest to longer duration without changing pulse period. Due to it, sludge can remove quickly from the narrow machining zone when the duration of pulse off time is longer and anodic dissolution can be controlled. This PWM is applied on step pulse waveform which is designed indigenously. In this waveform, two different peak voltages are incorporated into the pulse on time, resulting in potential transmission during each pulse on time is controlled. As a consequence, during each pulse on time, larger amount of material dissolution can be controlled precisely. To verify the feasibility of PWM technique, machining accuracy is investigated for different applied voltages, duty cycles, frequencies, and tool feed rates. In addition, the machined surface finish is also investigated under best parametric combination utilising different electrolyte concentrations. This PWM makes an effective contribution to profile accuracy, where at the movement of duty cycle from 30 % to 50 %, micro -groove width overcut is obtained as 34.026 mu m accompanied by less standard deviation of 1.24 mu m and taper angle of 14.030. By using this novel method, the machined surface roughness (Ra) is achieved as 0.0244 mu m, whereas Ra is 0.1609 mu m for the non-PWM method.