How is the start of the arc initiated in GTAW?

In Gas Tungsten Arc Welding (GTAW), the arc initiation process is crucial for establishing the welding circuit between the tungsten electrode and the workpiece. The correct method for starting the arc typically involves using a high-frequency start method or a scratch start.

The high-frequency start method generates a momentary high-frequency electrical current that creates a small arc between the tungsten electrode and the workpiece. This arc is very efficient in initiating welding as it allows the operator to maintain a safe distance from the workpiece until the arc is stable. Once the arc is established, the welder can then switch to the regular welding current.

Alternatively, a scratch start involves the welder touching the tungsten electrode to the base material and then lifting it slightly to establish the arc. This method is straightforward but can be less controlled and may lead to contamination of the electrode if not performed carefully.

Both methods are common in GTAW practice, but the high-frequency start is preferred for its advantages in arc stability and quality.