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

SMAW (Shielded Metal Arc Welding) and GTAW (Gas Tungsten Arc Welding) processes typically use constant current for their welding operations. This is because both welding methods require a stable arc length for proper operation.

In constant current systems, the machine adjusts the output voltage in response to changes in the arc length. When the arc length increases (as the electrode tip moves away from the workpiece), the machine lowers the voltage to maintain a steady current, preventing the arc from becoming unstable. Conversely, if there is a decrease in arc length, the voltage increases to keep the current at the set point. This regulation is crucial for maintaining the quality of the weld.

Constant voltage systems, on the other hand, are more commonly used in processes like GMAW (Gas Metal Arc Welding), where the arc length can vary more significantly without severe consequences for the welding process itself. Understanding this distinction is essential for anyone preparing for certification in structural welding, as it influences the choice of equipment and technique for different welding scenarios.