What is the tungsten tip shape recommended for AC welding?

• A. Sharp point
• B. Flat tip
• C. Rounded (ball) tip
• D. Tapered

Answer: (C)

In TIG welding, the shape of the tungsten electrode tip governs how smoothly the arc starts, maintains itself, and how quickly the tip wears. For AC welding, a rounded (ball) tip is best because it provides a larger, forgiving surface at the tip that helps start and stabilize the arc as the polarity switches. This rounded shape reduces tip erosion and tungsten contamination, which are more problematic when using AC, especially on aluminum where keeping the tip intact and the arc steady is crucial. A sharp point concentrates heat and wears quickly under AC, making arc stability and re-ignition more difficult. A flat or tapered tip also tends to produce less stable arcs on AC and can complicate maintaining a consistent arc length. So the ball tip supports easier arc initiation, steadier performance, and longer tip life during AC welding.