Development and Testing of Feedback Control System for Fused Deposition by Electrochemical Discharge (FDED) Process

Previous researches [1,2] on Fused Deposition through Electrochemical Discharge (FDED) process have revealed that the periodic instantaneous current wave form (ICWF) is the characteristic of the process and it is significant to maintain the nature of current waveform in order to have a deposition of consistent metallographic properties. The precise control of process parameters is essential for maintaining the current wave form. The standoff distance between electrodes (SOD) is the most critical parameter amongst all. Karnik, Ghosh and Shekhar [1] have shown that the piling up of metal occurring at the impingement zone during the deposition reduces the SOD resulting in higher current and higher rate of metal dissolution from the copper wire anode (tool). The higher metal dissolution from the anode eventually increases the SOD, resulting in lowering of current, the termination of discharge and reduction in deposition rate which leads to discontinuities in the deposition. The SOD, the deposition rate and current waveform could be maintained by controlling the instantaneous tool feed rate. In the present investigations, the instantaneous tool feed rate has been controlled in response to the feed back value of the ICWF as it indicates pile-ups as well as the instantaneous phase of the process. An algorithm using a combination of proportional and discrete event control to determine the tool feed rate has also been developed and tested to maintain the ICWF. The results demonstrate the effectiveness of the algorithm by revealing an increase in deposition rate and volume fraction of