Plasma arc welding (PAW) is an arc welding process, where a coalescence is produced by the heat generated from a constricted arc formed between a tungsten electrode and water-cooled (constricting) nozzle (non-transferred arc) or between a tungsten electrode and the job (transferred arc). The process uses two inert gases, one forms the arc plasma and the second shields the arc plasma.
Plasma Arc Welding (PAW) is an arc welding process similar to GTAW (TIG). The basic difference is in formation of the arc. In GTAW (Gas Tungsten Arc Welding) arc is started between the tungsten electrode and the job in the presence of inert gas. However in case of PAW, arc is initiated between the electrode and the nozzle in the presence of plasma gas and is known as pilot arc. The main Plasma arc is transferred to the job through the orifice of the nozzle which constricts the arc. Key process variables are current types and polarity, DCEN from a CC source is common, AC square-wave is common on Aluminium and magnesium, welding current and pulsing at frequency up to 20khz, gas flow rate (most critical parameter) etc.