Peak elimination of cross structures in wire and arc additive manufacturing using closed-loop control

Abstract

Abstract Peak elimination of cross structures has become a challenging issue in wire and arc additive manufacturing. This study proposes a control strategy to eliminate peaks in gas tungsten arc (GTA)-based additive manufacturing, i.e., adjusting the amount of filler materials at the peaks based on arc voltage signals. A novel algorithm, combining the anti-impulse interference moving average and the wavelet packet transform, is developed to filter disturbances in the arc voltage, and the deviation between the maximum and the minimum is less than 0.04 V. A Fuzzy-PID closed-loop controller is designed for arc voltage control and its parameters are determined by conducting multi-layer experiments. Comparison tests with open-loop and closed-loop controlled wire feed speeds are carried out to fabricate cross structures in GTA-based additive manufacturing. The results show that the deviation of the detected and given arc voltage at the peaks in the open-loop control test is more than 9 V, and that in the closed-loop control test can be controlled within 1 V. The peak generation in the open-loop control test results in the process termination. By contrast, the proposed control strategy using the arc voltage detection and filler wire control technique is extremely effective to eliminate the peaks in cross structures.