What type of current cleans the surface of aluminum when welding?

When welding aluminum, AC (alternating current) is the preferred choice because it possesses unique qualities that effectively address the challenges associated with welding this material. One significant advantage of using AC current is its ability to clean the oxide layer that forms on the surface of aluminum. This oxide layer can hinder the welding process by preventing proper fusion and penetration.

The alternating nature of AC current allows the welder to benefit from a cleaning action during the positive cycle of the waveform, where the aluminum anodizing is reduced and cleaned off. The negative cycle provides effective penetration. This dual action is especially crucial when working with aluminum, as it helps ensure a strong and clean weld.

In contrast, other types of currents, such as DC current, lack this cleaning feature and tend to struggle with aluminum due to the persistent oxide layer. Pulse current can have specific advantages in controlling heat and concentration, but it does not inherently provide the same cleaning effect as AC. Static current is not applicable in the context of welding altogether. Consequently, AC current remains the essential choice for effectively preparing aluminum surfaces in the welding process.