Welding aluminum with a Lincoln MIG welder opens up a world of possibilities for both hobbyists and professional fabricators. This versatile metal offers excellent corrosion resistance and a clean finish, but it demands specific settings and techniques to achieve strong, clean welds. Understanding the nuances of your Lincoln machine is the first step toward mastering this rewarding process.
Preparing Your Lincoln MIG Welder for Aluminum
Before you strike an arc, proper setup is critical for success with aluminum. This metal has a high thermal conductivity and a low melting point, which means your equipment needs to be dialed in precisely to avoid issues like burn-through or lack of fusion.
Essential Equipment and Consumables
You cannot weld aluminum with a standard MIG gun designed for steel. The process requires a specific setup to ensure proper shielding and smooth wire feeding.
Spool Gun: This is non-negotiable. The driving rollers in a standard push-pull system are too aggressive for the soft aluminum wire, leading to bird-nesting. A spool gun places the drive rolls near the weld puddle, eliminating friction and feeding issues.
Shielding Gas: Pure Argon is the standard gas for aluminum MIG welding. It provides the best arc stability and penetration. Do not use carbon dioxide or CO2 mixes, as they will cause excessive spatter and porosity.
Contact Tip: Use a contact tip specifically sized for aluminum wire, usually one size larger than steel wire. For example, if welding .030-inch steel, use a .035-inch tip for aluminum.
The Technical Side of Lincoln Settings
Lincoln welders often feature intuitive controls, but translating dial settings to aluminum requires precision. You are looking for a balance between heat input and travel speed to prevent the metal from melting away before the filler wire can join it.
Voltage and Wire Feed Speed
Aluminum requires lower voltage settings compared to steel of similar thickness. Start with a voltage setting that produces a tight, focused arc cone rather than a soft, flickering one. The wire feed speed must be high; you will likely be running at the maximum or near-maximum feed rate for the machine to maintain a stable arc. Adjust in small increments until you find the "sweet spot" where the wire melts smoothly into the puddle without popping or stubbing.
Gas Flow and Liner Considerations
Set your gas regulator to approximately 20-25 cubic feet per hour (CFH) for adequate coverage. It is also vital to use a plastic liner in your cable assembly rather than a steel one. Aluminum wire is soft and can easily groove a steel liner, creating friction that disrupts the smooth feeding of the wire.
Technique and Handling
Even with the perfect settings, the welder's technique dictates the quality of the bead. Aluminum demands a specific approach to heat management and travel pattern.
The Weave Pattern and Travel Speed
Unlike steel, where a slow "puddle" technique is often used, aluminum requires you to keep the weld moving. Hovering in one spot, even with the current turned down, will cause the base metal to melt rapidly and sag away from the filler wire. Use a slight side-to-side weave pattern to create a wider heat-affected zone while keeping the overall heat input moving quickly across the joint.
Managing Heat Input
Aluminum does not retain heat like steel; it dissipates it instantly. This means you need to maintain a consistent travel speed. If the weld begins to look colorless and shiny, you are moving too fast. If it turns brown or blue, you are moving too slowly or the voltage is too high. Practice on scrap material to calibrate your speed to the amperage of your specific project.
