What type of current type welding machines do SMAW and GTAW both use?

The correct answer is that both Shielded Metal Arc Welding (SMAW) and Gas Tungsten Arc Welding (GTAW) predominantly use constant current welding machines. Constant current machines maintain a steady current output even as the arc length varies. This is particularly important for both SMAW and GTAW processes because they rely on maintaining a stable arc to ensure good weld quality and control over the heat input during the welding operation.

In SMAW, the operator typically moves the electrode along the joint, which can change the distance from the base metal to the electrode; having a constant current helps manage changes in arc length effectively. Similarly, in GTAW, the use of a tungsten electrode requires precise heat control, which is facilitated by a constant current supply.

Understanding the role of current type is crucial for selecting the right equipment and ensuring the desired welding characteristics, which include penetration, bead appearance, and minimizing defects.