How to Troubleshoot Aluminum Welds

Clean the aluminum thoroughly if it is not welding properly. Contaminants interfere with the metal's welding ability. Wipe aluminum down with a solvent or an alkaline solution and rinse it. Scrub any oxide buildup off the aluminum with an aluminum-exclusive wire brush. Never use a brush on aluminum that has previously been used on steel.

Check your shielding gas that the torch uses. Argon gas usually works most effectively with aluminum, but add 25 percent helium if the aluminum is more than a half inch thick. This increases the temperature of the torch's arc and creates a stronger weld with thicker pieces. The lack of helium on thicker aluminum results in weaker welds that may not hold.

Look for black marks on the weld. This indicates the arc was too long or the torch was held at a bad angle. A healthy aluminum weld usually has a slight bright strip on either side of the welding point where the welding arc removed oxides.

Pull at the weld carefully after it has cooled and set. The weld should be tight and not brittle. A brittle weld indicates improper welding procedure and the adjacent parts might not have been adequately clamped during the weld.

Inspect the weld for warping. This indicates the aluminum got too hot, which can occur if the torch is kept in one place for too long or the torch made too many passes in a short period of time. This didn't give the aluminum enough time to cool so it started to melt, resulting in warping.

Add more filler material if the two aluminum objects being welded are heavier and the weld appears unstable or has cracks in it. The weld needs more support to hold.