What current type should be used for TIG welding aluminum?

TIG welding aluminum typically requires the use of alternating current (AC) due to the unique characteristics of aluminum as a welding material. When using AC, the current alternates between positive and negative polarity, which serves a dual purpose in the welding process. The positive half of the AC cycle provides cleaning action, effectively removing the oxide layer that forms on the surface of aluminum, thereby ensuring a clean weld pool. The negative half of the cycle provides the heat necessary for melting the aluminum and forming a solid weld joint.

This alternating characteristic is essential because aluminum oxide has a much higher melting point than aluminum itself, so maintaining a clean weld area is critical for achieving a strong, high-quality weld. Therefore, using AC allows for optimal welding conditions and successful fusion of the aluminum materials.

Other current types, such as direct current straight polarity or reverse polarity, are generally not suitable for aluminum. These methods do not provide the necessary cleaning action and may lead to poor weld quality and issues related to oxide contamination. Consequently, AC is the standard choice for TIG welding aluminum to achieve effective and efficient results.