Monitoring of Wire Arc Additive Manufacturing Using Current Transient Analysis

Cold Metal Transfer (CMT)-based Wire Arc Additive Manufacturing (WAAM) is a Metal Additive Manufacturing (MAM) process characterized by high productivity and scalability, but also by a strong sensitivity to process parameters, which makes effective process monitoring essential. The transient evolution of the welding current in CMT-based WAAM plays a critical role in deposition stability and overall process reliability. Conventional monitoring approaches often rely on global signal descriptors, which may not capture subtle variations occurring during the rising phase of the current waveform. This work proposes a time-domain characterization methodology specifically focused on the rising transient of the DC current in CMT-based WAAM processes. The transient is subdivided into two amplitude intervals, and slope-based indicators are extracted. The methodology is applied to three deposition conditions exhibiting different process outcomes. The results show that slope magnitudes and their relative variation between the two intervals provide clear discrimination between transient regimes, with one condition displaying significantly lower slopes. Overall, the proposed approach provides a quantitative and uncertainty-aware framework for time-domain monitoring of DC current transients in CMT-based WAAM processes, with potential implications for process stability assessment and real-time process monitoring.