Aluminum welding methods

 

Welding aluminum can be a very difficult task.  Aluminum has a higher thermal conductivity and a lower melting point than steel therefore welders need to follow specific guidelines.  Follow the rules of thumb offered here for selecting welding equipment, preparing base materials, applying proper technique, and visually inspecting weldments to ensure high-quality gas-metal-and gas tungsten-arc welds on aluminum alloys.

 

  • To weld aluminum, the welder  must  take proper care to clean the base material and remove any aluminum oxide and hydrocarbon contamination from oils or cutting solvents.

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  • Preheating the aluminum workpiece can help avoid weld cracking.

  • The push technique: With aluminum, pushing the gun away from the weld puddle rather than pulling it will result in better cleaning action, reduced weld contamination, and improved shielding-gas coverage.

  • Travel speed: Aluminum welding needs to be performed hot and fast.

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  • Shielding Gas: Argon, due to its good cleaning action and penetration profile, is the most common shielding gas used when welding aluminum. 

  • Welding wire: Select an aluminum filler wire that has a melting temperature similar to the base material. 

  • Convex-shaped welds: In aluminum welding, crater cracking causes most failures.

  • Power-source selection: When selecting a power source for GMAW of aluminum, first consider the method of transfer -spray-arc or pulse.

  • Wire feeder: The preferred method for feeding soft aluminum wire long distances is the push-pull method, which employs an enclosed wire-feed cabinet to protect the wire from the environment. 


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  • Welding guns: Use a separate gun liner for welding aluminum. 

  • Constant-current and constant-voltage welding machines can be used for spray-arc welding . Spray-arc takes a tiny stream of molten metal and sprays it across the arc from the electrode wire to the base material. 

  • In some shops, welders use the same wire feeders to deliver steel and aluminum wire. In this case, the use of plastic or Teflon liners will help ensure smooth, consistent aluminum-wire feeding.

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  • Use drive rolls designed for aluminum. Set drive-roll tension to deliver an even wire-feed rate. Excessive tension will deform the wire and cause rough and erratic feeding; too-little tension results in uneven feeding. Both conditions can lead to an unstable arc and weld porosity.

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  • Change liners often to minimize the potential for the abrasive aluminum oxide to cause wire-feeding problems.

  • Use a contact tip approximately 0.015 inch larger than the diameter of the filler metal being used - as the tip heats, it will expand into an oval shape and possibly restrict wire feeding.

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