Aircraft Maintenance

You want to hold the torch at the proper angle. If the torch is perpendicular to the work piece, it will be difficult to view the welding process.

The angle of the torch relative to perpendicular should be about 15 to 20 degrees. If this angle is exceeded too much, it can lead to less penetration, poor shielding gas coverage, and general arc instability.

In regards to travel direction, the torch should be pushed away from (ahead of) the weld puddle. This ensures proper gas coverage of the weld puddle and offers the welder a good view of the weld puddle.

Start Clean

Properly cleaning the area you will be welding is critical to a good weld result. Mike Sammons, sales and marketing manager for Weldcraft, points out, “Cleaning aluminum before GTA welding is essential to avoid contaminates, which can lead to lack of fusion, inclusions or porosity.” Be sure to wipe the base metal to remove any dirt, oil, grease or other contaminates.

Remove Oxides

When welding aluminum it is especially important to remove the oxides that naturally form on the surface. Aluminum oxide is the result of aluminum wanting to return to its natural state. Bare aluminum will oxidize as soon as it is exposed to the atmosphere, creating aluminum oxide.

Aluminum oxide is very hard (the only thing harder is a diamond). Its melting point is about three times that of aluminum. If not removed, it can lead to contaminated weld puddles or even prevent a weld puddle from properly forming.

Sammons discusses removing oxides from aluminum. “If you choose to remove the oxides mechanically, remember to designate the scraping tool or wire brush for that purpose only — using these tools for multiple jobs could cause contaminants to be introduced to the aluminum.