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Welding Aluminum With TIG & MIG

Posted in How To: Tech Qa on December 18, 2017
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Welding. There’s something almost supernatural about being able to melt metal and use it to glue other pieces of metal together. It’s an experience you must have if you’ve never done it before.

Welding requires skill, knowledge, and equipment. Some 15 or 20 years ago just a handful of 4x4 hobbyists were dabbling with metal inert gas (MIG) welding in their home shops, mostly welding steel. Since then, with advancements in welding technology and with more less-expensive MIG welders available on the market, just about everyone and their brother has picked up the stinger of a MIG welder to liquefy steel. Whether it’s to build rollcages, winch bumpers, or maybe even a full-tube-chassis 4x4, MIG welding steel outside of a full fab shop is fairly common nowadays.

Still, MIG and steel are not the only welding process or metals that the average off-roader is thinking about using as part of a 4x4 build. Aluminum is everywhere and can be built to be as good as—if not better than—steel in some applications, given the lighter weight. And while MIG is very versatile for steel and aluminum (with the addition of a spool gun), TIG (tungsten inert gas) welding is becoming ever more popular in the 4x4 hobby. That’s once again due in part to technology and more less-expensive TIG machines.

So if you’re like us and have fully immersed yourself in MIG welding steel, you’ve probably wondered what it would take to gather the tools and knowledge to weld aluminum. Would adding a spool gun and a tank of 100 percent argon to your welder satisfy your hunger for melting the lightweight metal, or do you need to buy more equipment and spend some time learning how to TIG weld? What are the pros and cons of each? What makes the most sense functionally and economically?

With a little help from our friends at Miller Electric we are going to delve into liquefying aluminum to answer these questions. Follow along as we take our first steps into TIG and MIG welding aluminum, discuss the pros and cons of each, and try to answer our own questions with a little help from our friends who actually know what they are doing, namely Rob Bonney of Rob Bonney Fabrication and Eric Eickhoff of Geiserbrothers.

I’m not an experienced TIG welder, but I do have lots of experience MIG welding and understand the TIG process. Still, like any new welder, I have a lot to learn, muscle memories to form, and experience to gain. With the excitement of a kid on Christmas morning, I assembled the Diversion 180 and Miller Electric Welding cart. The Diversion 180 comes with a gas regulator and hose, a foot-control remote (foot pedal), an 8-foot power lead with plugs for 110V and 240V, a 12-foot ground cable with clamp, a 12 1/2-foot Weldcraft A-150 TIG torch that is loaded with a 3/32-inch collet and collet body, and one 3/32-inch 2 percent ceriated tungsten electrode. We also have a Miller Electric Digital Elite welding helmet, a Tungsten specific mini grinder, a stainless steel wire brush we dedicate to cleaning only aluminum (or we could use Scotch-Brite pads), TIG-specific welding gloves, and a bottle of 100 percent argon shielding gas. We also bought 1 pound of ER 4043 1 1/6x36-inch welding rod.
The Miller Diversion 180 is easy to set up and has just a few selections you have to make before striking an ark. The first is an on/off switch. The second is a button to select which material you’d like to weld: “DC” for steel, stainless steel, and chromoly steel, or “AC” for aluminum. The third is a knob to set maximum amperage depending on the thickness, material, and type of welding you are doing. The machine does lots of thinking for you, which is good in this case since the machine knows way more about TIG welding than just about any new hobbyist welder. The foot pedal allows you to fine-tune the amount of amperage that is sent to the tungsten electrode. Lots of amperage is needed to start a weld and less to keep it flowing as you add welding rod.
With little guidance and plenty of ignorance and exuberance to try the new welder, I decided to build a few aluminum boxes, miniatures of fullsize parts I might build once I’m more experienced with aluminum. The plan was to build boxes with MIG and the spool gun and TIG using the Diversion 180.
Yeah, the welds on this cube cup made of a combination of 1/8-inch (0.120 inch) and 11-gauge (0.090 inch) aluminum aren’t perfect, but they give you the idea of how difficult this process is for someone untrained on a new machine. The specifics of TIG welding are very intricate: material thickness, specific material properties (there are several different types of aluminum), torch angle, weld wire diameter, amperage, tungsten grind, proper grounding, tungsten stick-out, arc length, and more all have an impact on how strong the weld is. TIG welding lessons are a good idea, but remembering all the fundamentals and practice, practice, practice are key to “getting” TIG welding. Mastering TIG takes a lot of hard work. We’ll consider this first half of a cube a decent first attempt.
MIG-welding aluminum requires a MIG-compatible welder (we have a Millermatic 190) 100 percent argon shielding gas, a welding helmet, MIG gloves, and a spool gun (we have a Miller Electric Spoolmate 100 Spool Gun). Aluminum is coated with a very thin layer of oxidation, so, as with TIG, cleaning the aluminum with an aluminum-dedicated stainless steel brush is a must.
The Spoolmate 100 comes with this nice protective carrying case and everything you see here, including a few 0.030-inch contact tips, a spool gun with a 12-foot cable, and a nozzle. Wire is not included, although there is a spot for an extra spool in the carrying case. Connecting the spool gun to the welder is simple. Loading the 1-pound spool of 0.030-inch ER4043 wire to the spool gun took a bit of care and practice. The reason for this, and the reason why the spool gun is necessary, is that wire like this is thin, relatively soft, and easy to kink while loading or while being spooled out by the welder.
As a comparison we decided to make another aluminum cube cup using the spool gun and MIG as a test and thicker 3/16-inch (0.188) plate. Experienced aluminum welders will notice one glaring issue with this and the TIG image earlier due to our inexperience. We should be grounding the aluminum directly rather than relying on the welding table as an adequate ground. Still, the welds turned out OK for a first attempt.
MIG-welding aluminum with a spool gun (cube on the right) is a fast-moving process. We were pretty happy with our first MIG beads, but you can see some issues with these welds specific to a MIG setup like this with a spool gun. When we started the weld bead, the materials were cold and the weld bead piled up (forming a convex mound). The middle of the weld looks pretty good, but the end of the bead is too hot, causing the weld puddle to drop down and create a small crater. You can also see the soot, spatter, and porosity that is associated with MIG-welding aluminum. Generally these welds are dirtier than properly done TIG welds.
In our nonscientific test we also MIG-welded a thinner cube as a comparison to the cube we TIG-welded earlier. Generally TIG-welding aluminum is better for thinner materials and MIG is better for thicker materials. This cube (like the TIG cube) is made out of a combination of 1/8-inch (0.120) and 11-gauge (0.090-inch) aluminum. These welds are ugly and share some of the issues with the 3/16-inch (0.188) cube with soot, porosity, and hot and cold areas.
Here are our three aluminum cube cups. On the far left is the MIG’d 3/16-inch (0.188) cube. In the middle is the MIG’d 1/8-inch (0.120) and 11-gauge (0.090) cube. On the right is the TIG’d 1/8-inch (0.120) and 11-gauge (0.090) cube. Some welds are adequate, others bad, but they’re all good enough for our purposes. Welding is not a skill you’re born with.
The last nonscientific test of our new aluminum welding was to fill each cube with a little water to see if they would leak. Because of aluminum’s properties and oxidation, porosity in aluminum welds is common. We were pleasantly surprised with the results, even though two of our cube cups had small leaks.

Cost to Liquefy Aluminum

So what does each of our two welding set-ups cost? This is assuming you have a welding helmet, general tools (like a stainless brush for cleaning aluminum), welding gloves, and so on. Sheilding gas, gloves, welding helmet are a financial wash because you need them for both processes.

Method 1
Miller Electric Millermatic 190 $969
Miller Spoolmate 100 spool gun $305
1 lb of 4043 0.030-inch aluminum welding wire $12
Total $1,286

Method 2
Miller Electric Diversion 180 $2,139
Miller Electric rebate on the 180 ($700)
Dedicated grinder for tungsten $30
1 lb 4043 1/16-inch aluminum welding rod $15
Total $1,484

Tips for Welding Aluminum

People have spent years mastering welding aluminum. Here are a few things to remember that should help you weld aluminum better using either TIG or MIG and a spool gun.

TIG
• Use pure argon for shielding gas.
• Use 2 percent lanthinated tungsten.
• Filler rod and tungsten size must be sized.
• Arc length and arc angle are critical.
• Use a dedicated grinder for your tungsten.
• Pencil-grind the tip with the wheel spinning towards the point. The point will ball.

MIG With Spool Gun
• Welding will go fast, so be ready. Increase travel speed, make shorter welds.
• Push the weld rather than pull it.
• Hold the stinger at 10-15 degrees.
• Use a longer stick-out length than with steel.

Both
• Check YouTube for tons of good videos from WeldingTipsandTricks.com.
• Clean the aluminum with a dedicated stainless steel wire brush or clean Scotch-Brite pads.
• Clean aluminum with acetone (and be sure to let it evaporate before welding).

Aluminum Welding With Professionals

Our pal, general automotive fabrication expert Rob Bonney, is a self-proclaimed “decent TIG welder.” Here he shows some fundamentals that we have already screwed up: the “pencil” grind on the tungsten, tungsten stick-out less than the diameter of the opening of the cup, and proper torch angle for welding a 90 like this. Also, he has the ground clamped directly to the aluminum and both pieces of aluminum are firmly held in place. Bonney also frequently uses Silicon Bronze rod to TIG-braze thin steel sheetmetal on bodywork. This method is not as structurally strong as TIG-welding steel but yields great results when modifying body parts.

Sources

Miller Electric
Appleton, WI 54912
920-734-9821
www.millerwelds.com

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