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How to Weld Quarter Inch Aluminum... in the wind.

 

 

Today's project involves compounding levels of difficulty and how we can do our best in the face of uncertainty. When we strive for excellence, the fear of doing a bad job can cause stress, especially when the work is challenging. It's important to trust that proper preparation, practice, and a good faith effort will yield good results in the vast majority of fabrication projects.

 

A client contacted me with a problem: The aluminum hinges on his flatbed truck were separating from the heavy fold-down panels. The panels were heavy duty extrusions and the kit was well-designed, but every single one of the eight hinges had cracks along the welds. The aluminum welds were clearly inadequate as they were the failure point. 8 hinges is not a huge task, but the flatbed had heavy equipment permanently mounted on it that prevented it from clearing the shop entrance.

 

Tig welding is hard. Tig welding aluminum is hard. Tig welding quarter inch aluminum outdoors when it's 10 degrees and windy was a little too Spartan for my taste. When you have a project with multiple factors contributing to its difficulty, it's best to figure out which of these multipliers can be eliminated or controlled.

 

For this project, that meant bringing the truck as close to the shop as possible, as the heavy amperage required to fuse 1/4" aluminum necessitated access to a 220v outlet or a generator that could provide adequate power. Additionally, working out of the shop provided homefield advantage with its familiar atmosphere.

 

I had the pleasure of working with the Miller Dynasty 280, which ran beautifully on 220. Quarter inch aluminum requires a lot of amps and an AC TIG process to ensure that the cleaning action of the alternating current can penetrate through the high-melting point oxide layer (1930°C). I'm sure some would say that DC TIG or even MIG would get the job done. For a welder who's #1 priority is upholding a good reputation, this was no time to take chances, especially not with someone else's work truck. Besides, the manufacturer already tried cutting corners on these welds, so that option had already been tried.

 

Preparation involved practicing lap welds on a 12 foot long flat bar of 6061. Aluminum is tricky, but I found it more forgiving than mild and stainless steel. It conducts heat exceptionally well, but its melting point is reached very suddenly and if you blink, you might miss it and wonder where that joint you were welding went. It's a beautiful metal.

 

For electrodes, I started out using 1/8" pure tungsten (green tip). In my experience, pure tungsten electrodes tend to ball up quickly, which is not undesirable. Many tig resources recommend balling up pure tungsten electrodes before beginning to weld. This can be achieved by adjusting your AC balance. In the end, I found rare earth tungsten (purple tipped) to be superior at handling high heat and the occasional dip.

 

Ultimately, you've got to do what you've got to do. After finding the right amperage and gas flow rate, the last thing I was fighting against was the freezing cold and persistent wind gusts.

 

 

 

Happy welding!

 

-Adan