Experimental analysis of electro-jet machining of thin metal sheets under the application of ultrasonic vibration, continuous and pulsed direct current

Abstract

Electrochemical machining is considered to be suitable for precision and micromachining without the development of residual stress, mechanical distortion and thermal damage. In this work, an in-house developed electro-jet machining system, a variant of electrochemical machining, has been used for machining in thin metal sheets, where the electrolyte is supplied in the form of a fine jet, concentrically to a wire electrode, through a nozzle. Machining performance was studied for generation of through slits of sub-millimetre range in 500 μm thick aluminium sheets, under the application of continuous and pulsed direct current (DC) power sources as well as with the application of ultrasonic vibration to the workpiece, emphasizing achieving better dimensional control with minimum overcut. A detailed investigation of the effect of applied voltage, scan speed, inter-electrode gap and electrolyte concentration has been performed in the case of continuous DC supply on quality factors, kerf-width, amount of overcut and material removal rate. Furthermore, the effects of duty cycle and pulse frequency in the case of pulsed DC supply, and the effect of vibration frequency under the application of ultrasonic vibration have been analysed on the above-mentioned output factors. Though a pulsed DC power supply with a pulse frequency of more than 1 kHz and a small duty cycle was found suitable for precision machining among all conditions, ultrasonic vibrations proved beneficial for fine feature generation with tighter size control at higher frequencies (lower vibration amplitude).