When I first started welding aluminum with a MIG machine, I’ll be honest—it didn’t go smoothly. I thought, “Hey, it’s just like steel, right?” Well, not quite. Aluminum has its own set of rules, and if you don’t respect them, it can turn into a frustrating, messy experience real quick.
One of the biggest lessons I learned early on is that getting the wire speed and voltage right is critical when MIG welding aluminum. Too fast, too slow, too much voltage, or too little—and the weld can look ugly or even fail completely.
Photo by mig-welding.co.uk
I want to share everything I’ve learned about dialing in the perfect aluminum MIG weld. I’ll walk you through how wire speed and voltage affect aluminum welding, show you an easy-to-follow chart, and share a few personal tips that made a big difference for me.
If you’re ready to make strong, clean, good-looking aluminum welds without all the headaches, you’re in the right place.
Why Aluminum Welding is Different Than Steel
Before we even touch the settings, let’s talk about why aluminum acts so differently.
Aluminum is:
- Much more thermally conductive than steel. It pulls heat away from your weld faster.
- Softer and more sensitive to heat input.
- Prone to oxide formation, which requires proper cleaning before welding.
- More fluid when molten, making it harder to control the puddle.
Because of these differences, your wire speed and voltage settings need to be hotter and faster than you might be used to with steel.
It’s a little tricky at first, but once you get the hang of it, you’ll love welding aluminum.
Wire Speed for Aluminum MIG Welding
Wire speed controls the amount of filler material being fed into your weld puddle. When you’re welding aluminum, you generally want a higher wire speed compared to steel for the same thickness.
Here’s why:
- Aluminum needs more filler to build a stable weld puddle.
- Faster feeding helps prevent burn-through and maintains arc stability.
- Higher speeds also help reduce porosity by keeping the puddle fresh.
I like to think of it as staying one step ahead of the heat. Move too slow, and the puddle gets away from you.
Voltage for Aluminum MIG Welding
Voltage, on the other hand, controls the length and “softness” of the arc.
With aluminum, you typically want a higher voltage to:
- Keep a wider, smoother arc.
- Prevent a narrow, digging arc that can cause burn-through.
- Help with puddle fluidity for better fusion.
The right voltage gives you a nice, smooth-sounding arc that feels stable—not too hissy or aggressive.
Aluminum MIG Welding Wire Speed and Voltage Chart
Now, let’s get to the part everyone’s waiting for: the chart.
This chart gives you a strong starting point. These are not exact settings for every machine, but they’ll get you close enough that you only need minor tweaks.
| Material Thickness (inches) | Wire Diameter (inches) | Wire Speed (IPM) | Voltage (Volts) |
|---|---|---|---|
| 1/16″ (0.0625″) | 0.030 | 250–300 | 16–18 |
| 1/8″ (0.125″) | 0.030 or 0.035 | 320–400 | 18–20 |
| 3/16″ (0.1875″) | 0.035 or 0.045 | 400–450 | 20–22 |
| 1/4″ (0.250″) | 0.035 or 0.045 | 450–500 | 22–24 |
| 3/8″ (0.375″) | 0.045 | 500–550 | 24–26 |
Always run a few practice beads on scrap material first before committing to your project. Every machine has slight variations.
How to Adjust Settings Based on Your Work
Even with a good chart, you’ll still need to fine-tune a little. Here’s how I like to think about it when adjusting wire speed and voltage:
- If your weld is sitting high and cold, increase wire speed and voltage a little.
- If your weld is sinking and burning through, lower wire speed and voltage slightly.
- If the arc sounds angry or unstable, your settings are probably mismatched.
- Listen for a steady, smooth “hiss”—that’s what you want.
It’s all about small moves. Don’t crank the knobs wildly. Tiny tweaks make a big difference.
Essential Equipment for Aluminum MIG Welding
Welding aluminum needs a few special pieces of equipment to get the best results.
Spool Gun or Push-Pull Gun
Aluminum wire is so soft that it can birdnest (jam up) inside a regular MIG gun liner. Using a spool gun or a push-pull system keeps the wire moving smoothly.
If you’re serious about aluminum, investing in a good spool gun will save you a ton of frustration.
Proper Shielding Gas
For aluminum, you need 100% argon gas.
Using mixed gases like 75/25 (argon/CO2) that work for steel will cause ugly, porous welds with aluminum.
Make sure your regulator is set right, usually between 20–30 CFH depending on how windy your environment is.
Clean Base Material
You absolutely must clean the aluminum before welding.
- Use a stainless steel wire brush that’s only for aluminum.
- Remove any oils or contaminants with acetone.
Even a tiny bit of dirt or oxide can ruin an aluminum weld.
Common Mistakes to Avoid
Let’s talk about a few mistakes I made early on so you can skip them:
- Not preheating thicker material: For thicker aluminum (over 1/4″), a slight preheat (around 200°F) can help a lot.
- Holding too long in one spot: Move fast! Aluminum doesn’t give you much time.
- Incorrect contact tip size: Always use contact tips designed for aluminum wire.
- Ignoring practice time: Aluminum feels different. Take your time getting used to it.
There’s no shame in burning a few pieces of scrap to get that muscle memory dialed in.
Fine-Tuning Your Weld: Sounds, Sight, and Feel
I always tell folks that welding aluminum is about the whole experience. You should be paying attention to:
- Sound: A steady, soft “hiss” means you’re on point.
- Sight: A shiny, flat bead without craters or undercut.
- Feel: A stable arc that doesn’t jerk, stutter, or spit.
Trust your senses. They’ll tell you a lot about what’s happening before the weld even cools.
Quick Troubleshooting Table
Here’s a table I made to help spot issues fast:
| Problem | Likely Cause | Quick Fix |
|---|---|---|
| Burn-through | Too much voltage or slow speed | Lower voltage, increase travel speed |
| Cold weld (no fusion) | Too low voltage or speed | Increase voltage and/or wire speed |
| Birdnesting (wire jam) | Liner issue or too soft feed | Use spool gun, check drive tension |
| Excess spatter | Wrong gas or settings | Use 100% argon, adjust settings |
| Porosity (tiny holes) | Dirty metal or poor gas coverage | Clean base metal, check gas flow |
Keep this handy when you’re setting up or troubleshooting—it’ll save you a lot of headaches.
Final Thoughts on Aluminum MIG Welding
Welding aluminum with MIG is a special skill that takes a little more patience, but once you master the basics, it opens up a lot of possibilities.
Whether you’re repairing trailers, building custom parts, or working in a fab shop, having the right wire speed and voltage makes all the difference.
Always remember:
- Use the proper equipment.
- Clean your materials.
- Start with a good chart.
- Adjust carefully based on how the weld feels, sounds, and looks.
If you respect aluminum, it’ll reward you with strong, beautiful welds. And trust me, there’s no better feeling than laying down a perfect, shiny bead on aluminum. It’s just pure satisfaction.
FAQs About Aluminum MIG Welding Wire Speed and Voltage
What wire is best for MIG welding aluminum?
For MIG welding aluminum, ER4045 and ER5356 wires are commonly used. ER5356 is stronger and better for structural work, while ER4045 offers better crack resistance.
Can I MIG weld aluminum without a spool gun?
Technically, yes, but it’s difficult. Without a spool gun or push-pull system, soft aluminum wire can tangle easily. A spool gun is highly recommended for consistent results.
Why does my aluminum weld look dirty?
Dirty aluminum welds usually happen because of poor base metal cleaning or contaminated shielding gas. Always clean the metal with a stainless brush and use 100% argon gas.
How do I know if my wire speed is too fast?
If your wire is pushing hard against the weld pool or causing spatter, your wire speed might be too high. Try reducing it slightly until the arc feels more stable.
Is it better to push or pull when MIG welding aluminum?
You should always push when MIG welding aluminum. Pushing improves gas coverage and results in a cleaner weld.
