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ESAB is a brand known for welding equipment. Being one of the leading suppliers of welders, it makes machines capable of many things, including aluminum welding. So the quick answer to the question is yes.
TIG Welding Aluminum with ESAB Rebel Welders
Multi-process machines don’t always come with the capability to weld aluminum, which is quite a challenging material for welders. ESAB is well-known for its multi-process welders, so we’re really talking about welders that can do MIG, stick, and TIG. These multi-purpose machines are portable and versatile, and that’s why hobbyists as well as professionals buy and use them.
The ESAB Rebel welders are jack of all trades with AC/DC outputs and, therefore, can TIG weld several materials, including stainless steel and aluminum.
Is Aluminum Difficult to Weld?
There are challenges when it comes to welding a material with a low melting point. Pure aluminum melts at 660 degrees Celsius, much lower than steel, for instance. That makes it easy for you to burn holes through a sheet of aluminum, instead of doing actual welding.
The properties of aluminum make it more difficult to weld than other metals. It conducts heat quite efficiently. That also causes it to distribute heat fast. That means a sheet of aluminum requires a great deal of heat during welding despite its relatively low melting point.
Some aluminum alloys are also prone to hot cracking. Hence, choosing the right filler is an important consideration to avoid fissures that compromise the integrity of the welded joints.
The reactivity of this metal means it readily forms an oxide layer on its surface. This oxide layer has a much higher melting point (1370 degrees Celsius). Hence, you need an initially higher temperature to melt the thin oxide film. Still, you need to wash the workpiece with acetone or a strong acid or alkaline to remove the oxide layer prior to welding.
Another reason to remove the oxide layer before welding is because aluminum oxide is heavier than pure aluminum and tends to mix into the pool and affect the strength of the joint.
Working Around These Challenges
GTAW or TIG is a slow welding process, which is why you don’t see welders in high-production shops resorting to it. It does have its advantages, though. A slow, more controlled process is definitely something needed when welding aluminum. In this case, we’re more concerned about quality more than speed and productivity.
Some welders would MIG weld aluminum, but it’s a tricky, if not a problematic, process. With MIG, you have to feed the filler rod into the weld pool just as soon as you hit the gun trigger. No preheating is done. Without preheating, you run a risk of poor fusion and penetration.
With TIG, however, you can ensure good penetration because you can control the timing of melting the tip of filler metal into the puddle. Nonetheless, a skilled welder can use TIG or MIG for welding aluminum. It’s just that we all want to choose the more convenient option. And if you have a multi-process machine like an ESAB 205ic or 215ic, there’s no reason to not use its TIG function to work with aluminum.
Proper heat distribution is crucial for welding aluminum properly. Again, the material conducts heat efficiently, distributing heat throughout itself during welding. Preheating aluminum seems counterintuitive since it has a low melting point compared to other metals. There are a number of ways to preheat an aluminum workpiece. You can use an oxy fuel torch or a propane torch.
Aside from preheating the entire workpiece, you also need to preheat the joint before adding the filler material. The heat from the arc should burn away the oxide layer. This stage is quick. Once you’ve burned through the oxide skin, a puddle forms — and this is when you add the filler material.
When burning the oxide layer away, you don’t want to be so aggressive as to create a runny puddle or melt holes through the sheet. You can avoid this by using a shorter arc to focus the heat to the needed area. Using a longer arc raises the arc voltage and heats up a larger area but creates a runny puddle.
The Right Polarity Matters!
As mentioned earlier, cleaning the workpiece before welding is an important step to remove the oxide layer. However, this layer reforms quickly. This is why it’s important to use AC polarity when TIG welding aluminum.
Welding with AC creates a current flow that changes as you run the bead. The electrode positive portion of the cycle removes the oxide layer, while the electrode negative part melts the base metal and allows you to incorporate the tungsten into the weld pool. Depending on the set frequency on the machine, this cycle happens 50, 60, or 120 times a second.
Most ESAB Rebel welders run at 50/60 Hz, good starting frequencies for buildup work. For general welding, you’re looking at a range of 80-120 Hz, but fillet weld application demands full penetration and a higher frequency (i.e. 200 Hz). Fortunately, the 205ic and the 215ic have a TIG range of up to 400 Hz (1).
What About the Amperage?
There’s a simple rule for TIG welding aluminum: 1 amp for every thousandth of an inch of material thickness. So if you’re welding a 1/8” (0.125”) thick aluminum, then you need 125 amps. This rule is good until you get to a quarter of an inch of material thickness, which would require about 250 amps. After that, the rule no longer applies.
If you’re welding a 3/8” material, you’re all right with 280 amps. Anyway, you don’t need to worry about higher amperage for light welding operations, which you can do with the ESAB Rebel EMP 205ic or 215ic. If you’re doing industrial fabrication stuff, you need to invest in something like the 235ic or even the 285ic.
The Bottom Line
We’ve pretty much laid out that the ESAB Rebel multi-process welders can TIG weld aluminum. Basically, it’s a matter of choosing the right settings and technique as well as preparing the material beforehand.