Metal-inert-gas (MIG) welding is a type of arc welding that uses a metal electrode that matches the alloy of the work piece and an inert gas to displace oxygen from the weld area. MIG welding is the most appropriate welding technique for aluminum, with the exception of extremely thin aluminum sheeting. MIG welding aluminum requires more experience and finesse than welding steel.
Things You'll Need
- Aluminum parts to be welded
- Wire brush
- MIG welding machine
- Aluminum filler wire
- Argon shielding gas
- Welding safety equipment (mask, gloves, clothing)
Prepare the surfaces of the aluminum parts by cleaning the surfaces with a solvent, then using the wire brush to remove any oxides. This removes any particles and impurities and prevents them from becoming trapped in the weld.
Hold the electrode at a 10- to 15-degree angle from the vertical, pointed toward the direction of the weld. It is important to use the push method when MIG welding aluminum. The pull method would prevent the argon gas from adequately covering the weld, resulting in an inconsistent weld.
Create a pool of molten aluminum with the electrode and slowly push the electrode forward. Adjust the voltage of the welding machine to achieve spray transfer of the aluminum electrode. In spray transfer, the electrode releases small droplets of the metal into the weld. This method results in a smooth weld and the droplets do not interfere with the electrode arc.
Adjust the movement rate of the electrode as the aluminum work piece heats up to maintain a consistent weld width. If a large fillet weld is required, make several thin passes as opposed to one thick pass, which has the potential to burn through the material.
Tips & Warnings
- The filler wire used for MIG welding aluminum must match the alloy of the aluminum parts to be welded. The parts of the welding gun that contact the filler wire must be sized to match the diameter of the filler wire.
- MIG welding is a hazardous activity. Welders must wear protective equipment, including a mask, gloves and flame-resistant clothing to prevent eye damage and burns.
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