What type of AC wave is often used for aluminum welding in GTAW?

The type of AC wave that is most commonly utilized for aluminum welding in Gas Tungsten Arc Welding (GTAW) is square wave AC. This waveform offers significant advantages when working with aluminum, as it provides a more focused and adjustable arc that can penetrate better into the base material.

Square wave AC has distinct transitions between positive and negative polarities, which aids in effective cleaning of the aluminum surface by removing the oxide layer. This cleaning action is crucial because aluminum forms a thick oxide layer that needs to be broken down for proper fusion during welding. The sharp transitions of a square wave enable a higher frequency cleaning effect compared to other waveforms, making it more efficient for aluminum applications.

Additionally, square wave AC allows welders to adjust the balance between the cleaning and welding current, giving them control over the depth of penetration and heat input. This flexibility is particularly valuable in achieving high-quality welds in aluminum materials, which often require precise temperature control to avoid warpage or burn-through.

In contrast, sine wave AC does not provide the same level of cleaning action, while modified sine wave AC may not deliver the optimal balance required for aluminum welding. Pulse wave AC can be effective for certain applications, but it is typically not the primary choice for aluminum welding in