What feature relates to cleaning action in GTAW?

• A. Sine Wave
• B. Heat input
• C. Electrode size
• D. AC balance

Answer: (D)

Cleaning action in GTAW is controlled by how long the arc spends in the positive portion of the AC cycle. When the workpiece is positive, the arc tends to cleanse the surface oxide before fusion, exposing fresh metal for welding. The AC balance setting adjusts the percentage of time the arc is in that positive, cleaning phase versus the negative, welding phase. More positive time increases cleaning action but can reduce penetration and arc stability; less positive time reduces cleaning but can improve penetration. The other factors—the sine-wave nature of AC, heat input, and electrode size—affect different aspects of welding, but the feature that directly governs cleaning action is the AC balance.