Aluminum TIG/MIG Welding

Owned by Luke Sinka
Jan 31, 2022
2 min read

For whatever applications, most likely a cheaper and lighter replacement for copper, welding aluminum is tricky. So here is some research on the challenges and solutions.

  • Oxide layer

    • You need an AC TIG or MIG welder to penetrate the aluminum oxide layer which naturally forms on aluminum within seconds of being exposed to air

    • Clean the surface before welding with either a wire brush (used exclusively for aluminum) or an acid/base (such as acetone). If you use any liquids always dry the part before welding

  • More prone to impurities/porous welds

    • While molten, aluminum attracts impurities more than steel including hydrogen gas. The gas is then released when the aluminum solidifies making the weld porous

    • Use soap or the like to remove oil/dirt before welding

    • Use proper shielding gas and don’t make unnecessarily long arcs

  • Cracking

    • Preheat the piece (<110ºC or 230ºF) to help prevent weld cracks

 

AC welding itself is part of what makes welding aluminum difficult. Here are some things to consider.

  • Electrode

    • A pure tungsten electrode is most commonly used for aluminum

    • Use an electrode ~0.5 mm (0.02 in) larger in diameter than the filler metal you’re using

  • Frequency

    • Not that important, especially for standard/simple welds

    • Somewhere around 70 - 120 Hz should work well

  • Balance/Cleaning/Penetration

    • This is important

    • The % of the time the electrode is negative

    • While a lower balance (more electrode positive) increases the amount of oxide the arc can get through (cleaning), the tungsten electrode will split, lose its point, and/or spit if it is positive for too long

    • A higher balance (more electrode negative) lowers the time it takes to melt the aluminum, increases how deep into the metal the weld goes (penetration), and keeps your electrode in one piece

    • Probably keep between 80 - 90%

 

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