Research And Development On Feeding Set-up Used In Micro Electrochemical Machining With Ultra-pure Water

In Micro-ECM, it is necessary to solve the problem of localization of anodic dissolution, and hard to control the gap between the electrodes, which is micro scale. As to these properties, the author try to use ultra-pure water as electrolyte and to controll the gap in a very small scale, which was smaller than 50 micrometers. As has been confirmed, small gap was very useful to the localization in anodic dissolution, but it led to another two problems: Firstly, how to enhance the current density in machining area and make it qualified to the requirement of ECM; Secondly, how to control the small gap and make sure of its stabilization in machining process. As to the first one, the researchers adopted the method of putting ion-exchange resins or ion-exchange membrane between the electrodes in ultra-pure water, thus it enhanced the degree of water dissociation, also enhanced the current density. As to the second one, it is necessary, according to the properties of Micro-ECM, to apply a suit of feeding mechanism. the mechanism, which can feed in 10~100 nanometers order, will be driven by piezoelectric ceramic actuator, in addition, it will be driven by step motor to adjust the gap between anode and cathode. To qualify the requirement of high resolution, high precision, enough journey and flexible operation of the mechanism, a suit of power to drive PA 50/12 piezoelectric ceramic actuator and a controller to control the voltage were designed. The controller, which was controlled by MCS-51 microprocessor, can reset and clear the power voltage, also can set the ascending time and adjust the voltage step by step, thus control the output displacement. In the end of the paper, the execute status of the driven mechanism was detected and a series of technological tests were performed, also, how the technological parameters influenced the results of micro-ECM were analyzed.