Qu'est-ce que le soudage MIG de l'aluminium ?

If your aluminum welds keep cracking or look dirty, you’re probably using the wrong method—or the wrong settings.

MIG welding aluminum is a process that uses a wire electrode and shielding gas to create strong, clean welds quickly, especially on thicker aluminum parts.

Most people assume welding aluminum is the same as welding steel. But it’s not. Aluminum behaves very differently. Its melting point is lower. It conducts heat faster. And it’s more sensitive to contamination. If you want to avoid weak joints, poor penetration, or messy finishes, you need to understand how MIG welding works specifically for aluminum.

How does MIG welding differ for aluminum?

If you’re using the same MIG settings for aluminum as you do for steel, you’re likely wasting wire, burning through material, or making porous welds.

MIG welding aluminum needs higher voltage, faster travel speed, and pure argon shielding gas to work effectively.

Aluminum is much more thermally conductive than steel. That means heat spreads quickly, which can make it hard to get proper fusion. To deal with this, I always increase voltage and wire feed speed when switching from steel to aluminum. Also, while steel often uses a CO2/argon gas mix, aluminum needs 100% argon to avoid oxidation and porosity.

Key Differences Between Welding Steel vs. Aluminum (MIG)

When MIG welding aluminum, cleanliness is crucial. Oxides on the surface melt at a much higher temperature than the base metal. That’s why I always brush the surface with a stainless steel wire brush and wipe it with acetone just before welding.

What equipment is needed for MIG welding aluminum?

If you’ve ever struggled with bird-nesting wire or inconsistent arc starts, chances are your setup isn’t made for aluminum.

To MIG weld aluminum properly, you need a spool gun or push-pull system, 100% argon gas, aluminum-compatible wire, and a machine with high amperage capacity.

Welding aluminum with a standard MIG welder can be frustrating. The soft aluminum wire tends to tangle inside the liner—this is called bird-nesting. I learned early on that using a pistolet à bobine, where the wire is fed just a few inches from the arc, helps avoid this issue completely. Alternatively, high-end setups use pistolets à tirer et à pousser to keep consistent wire feed even through longer cables.

Essential Equipment for MIG Welding Aluminum

Another thing to consider is transfert par pulvérisation. Unlike steel, short-circuit transfer doesn’t work well with aluminum. It creates a cold weld with poor fusion. So I always set my machine for transfert par pulvérisation, which gives smoother and stronger welds, especially for aluminum over 1/8 inch thick.

What are common problems when MIG welding aluminum?

If your aluminum welds look porous, cracked, or dirty, you’re not alone. Even experienced welders face these issues.

Common problems include porosity, cold starts, lack of fusion, wire feed issues, and oxidation from poor surface prep.

I’ve made all the classic mistakes when starting out. One of the most frustrating is porosity—tiny holes in the weld bead caused by contamination. It often comes from moisture, dirty base metal, or the wrong shielding gas. I always triple-check gas flow (20–30 CFH) and clean the metal right before welding.

Another issue is wire feed inconsistency. Aluminum wire is soft. If the liner or rollers aren’t designed for aluminum, it will jam or slip. That’s why using a Teflon liner et U-groove rollers is non-negotiable in my setup.

Troubleshooting MIG Welding Aluminum Issues

It’s also worth mentioning that humidity and ambient air can affect aluminum welding more than steel. I’ve found that even slight condensation on the material can cause major weld issues.

Is MIG or TIG better for welding aluminum?

If you want clean, strong, and fast welds on aluminum, choosing the right process matters a lot.

MIG is faster and better for thicker aluminum, while TIG gives more control for thinner parts and cosmetic welds.

When I’m working on high-volume jobs like structural parts or thick aluminum panels, I always go for MIG. It’s faster, easier to automate, and more forgiving with fit-up. But when a project requires precision—like visible joints on furniture or thin tubing—TIG is my go-to. It offers full control over heat and filler.

MIG vs. TIG for Aluminum Welding

One downside of MIG is that it’s harder to weld very thin aluminum (<1.5mm) without burn-through. On the other hand, TIG needs both hands and sometimes a foot pedal, so it’s not great for long production runs. I often recommend MIG for structural strengthet TIG for cosmetic quality.

Conclusion

MIG welding aluminum takes special equipment, clean prep, and a good understanding of how aluminum behaves. With the right approach, it’s a fast and effective method, especially for thicker parts.