Evaluation of Arc Welding Process Using Digital Storage Oscilloscope and High Speed Camera

Digital Storage Oscilloscope (DSO) and a high speed camera with laser light illumination are used to monitor manual metal arc (MMA) welding process. Welding was carried out using different type of welding power sources and electrodes. Dynamic variation in current and voltage was recorded using a DSO with very high sampling of four Giga samples/s. Arc welding process was imaged using high speed camera simultaneously. Data obtained from DSO were subjected to time domain and statistical analysis. Probability density distribution (PDD) analysis of the voltage and current signals were carried out.

The results showed that a proper filtering should be applied for the raw data collected using DSO to generate useful information. It was possible to correlate various physical processes that occur during welding with corresponding variations in voltage and current. High speed images from the camera enabled to view the physical processes that occur during arc welding and hence helped to obtain this one to one correlation. Statistical analysis showed that PDD generated from the acquired data is unique to a welding power source or a consumable or a welder. Hence PDDs can be used to evaluate performance of power sources or consumables. Accordingly, separate PDDs for a inverter and a generator power source were produced. By combining both imaging and DSO signals it was also possible to show different modes of metal transfer in arc welding process. Thus the feasibility of monitoring arc welding process using DSO and high speed camera has been demonstrated successfully.