Application of Time-Frequency Methods for Assessment of Gas Metal Arc Welding Condition

Gas Metal Arc Welding (GMAW) is a popular method of material joining, widely used for a variety of critical industrial structures. Assuring high quality of joints is than a vital task. Welding is a highly dynamic and non-linear process, thus an application of time-domain or frequency-domain methods is often not suitable for evaluation of welded joints quality. To fully describe the correspondence between the geometry of welding arc, parameters that express the quality of joint, and the welding arc current, being the most important steerable parameter of a GMAW, time-frequency methods (TFM) of signal analysis should be applied. In the paper application of ensemble of STFT and EMD (Empirical Mode Decomposition)-based estimators to evaluate the stability of a GMAW process, that results in the quality of joint. Proposed method of feature extraction was applied on the real data taken during several GMAW realizations with different conditions (changes in welding current, arc voltage, shield gas flow, wire feed speed, etc.). In the active experiment process parameters were acquired. Performed investigations revealed that in comparison to traditional as well as separately used TFM, ensemble of TF estimators gave better performance in a GMAW condition assessment.