Process Stability Criterion for MIG Welding

The term “Process stability" refers to the dynamic behaviour of the welding arc. In MIG welding process it depends on number of factors like power source characteristics, shielding gas, welding conditions, mode of metal transfer and wire chemistry etc. However the influence of each of these factors on the process stability is reflected in the current and voltage waveform of the welding arc. Since the current and voltage signals of an arc welding process are stochastic signals by nature, it requires statistical signal theory for evaluating the process stability. Therefore the current and voltage signals are measured using high speed data acquisition system and analysed. This paper presents the results of the investigation carried out on the influence of shielding gas mixture on the process stability in solid wire MIG welding under short circuit and spray transfer conditions, using statistical approach.