Читать книгу Welding Metallurgy - Sindo Kou - Страница 32

The tungsten electrode sticks out of the shielding gas nozzle in GTAW (Figure 1.12b), but it is recessed in the orifice gas nozzle in PAW (Figure 1.15b). Consequently, arc initiation cannot be achieved by striking the electrode tip against the workpiece as in GTAW. The control console allows a pilot arc to be initiated, with the help of a high‐frequency generator, between the electrode tip and the water‐cooled orifice gas nozzle. The arc is then gradually transferred from between the electrode tip and the orifice gas nozzle to between the electrode tip and the workpiece.