Mastering TIG welding aluminum takes some practice because it’s more challenging to weld than other metals like steel. But with the right techniques and a few tricks of the trade, you can seamlessly fuse pieces of aluminum together.

TIG welding technique allows for precise control and produces strong, low-porosity welds. It’s easy for aluminum to burn during welding. Also, the final products could have defects if you can’t manage variables, like heat input and using the correct electrode.

We’ve suggested 10 crucial tips for aluminum TIG welding. Following these best practices will help you create strong, clean welds, which are free of cracks and pores. 

What is TIG Welding?

TIG welding uses an arc between a non-consumable tungsten electrode and the metal pieces being joined to melt and fuse them together. In this process, it’s possible to control the location and size of the weld precisely. 

This precise control makes TIG ideal for welding thin metal materials that require accurate welds with little distortion. So, it’s great for welding in precision machining services. Parts welded with TIG often don’t need much grinding or finishing work after as the process leaves a smooth, clean weld bead. 

Comparing TIG vs MIG welding, the latter is used for welding thicker materials. It’s also faster and less expensive than TIG, suitable for mass production. 

While it takes more skill to use than other welding methods, TIG allows for welding of both ferrous and non-ferrous metals, like aluminum and stainless steel. The process is commonly used in industries like sheet metal fabrications, auto manufacturing, aerospace and medical device production where you need high quality, defect-free welds for advanced precision machining components. 

10 Tips for Tig Welding Aluminum

TIG welding aluminum can be tricky because it cools down so fast and its heat conductivity makes it hard to keep a steady bead. But with some practice and know-how, you can get great welds every time.

These 10 tips will help you overcome aluminum’s challenges and improve your welding skills. 

1. Keep Everything Clean

Aluminum is very reactive and even tiny amounts of contaminants can cause problems. So, it’s worth taking the time to thoroughly scrub all materials before welding.

Even oils from your hands or tools can cause issues, like porosity, in the weld. So, use a good degreasing cleaner and cloth to wipe down all surfaces. Check the welding rod carefully because it can look shiny but still have residue. 

Don’t forget to clean off any paint, rust, or anodizing. Use sanding or wire brush but do so after degreasing, so you don’t drive contaminants deeper into the pores. For heavy deposits, a non-woven abrasive disc works well.

Just before welding, give the joint area a final going over with a dedicated wire brush. Use separate brushes for different metals to prevent any cross-contamination when switching materials. 

Following these simple cleaning steps will make a clear difference in your weld quality. 

2. Preheat the Aluminum

Warming up the metal will make the process smoother. Some types of aluminum need to be preheated more than others, such as the high-density alloys. On the other hand, it’s possible to weld the low-density alloys without preheating.

However, preheating is the best practice to TIG weld aluminum because it makes the arc easier to control and produce cleaner-looking welds. 

If the metal is cold, you may find it difficult to get the welding machine settings just right. The arc might bounce around more or dig into the aluminum too much. When preheated, the welding current can flow smoothly without damage.

3. Choose the Right Filler Rod

Want to learn one of the best tips for aluminum TIG welding? Pick a filler rod that matches the aluminum alloy you’re joining! Different alloys have varying chemical makeups, so using the wrong filler can lead to problems. 

Some alloys and their correct filler rods are:

• For 6xxx series alloys, like those used in plates and extrusions, use a 5356 filler rod. 
• A 1100 filler will provide a strong bond on the 3003 alloys, used for body panels on cars and bikes.
• You can use both 5356 and 4043 rods for 5XXX series alloys.
• Alloys used for cast parts usually contain silicon, so a 4043 rod is a safe choice in most cases.

Apart from the correct type, you have to pick a filler rod with the correct thickness. For example, for thin aluminum under ⅛-inch, a rod near that diameter will provide good penetration.

And don’t use scraps of the base metal as filler, even if it seems logical. Some alloys like 6061 could crack if re-welded with themselves as filler instead of a proper rod.

4. Use the Correct Tungsten Electrode

The type of tungsten electrode you choose for TIG welding aluminum makes a big difference. Tungsten carries the electric current to create the welding arc. But some types work better than others on different metals.

For aluminum, you need a pure tungsten or zirconiated electrode. These form a small ball on the tip during welding and that ball transfers heat well to melt the metal.

The most common electrodes for welding steel and stainless steel are thoriated and lanthanide for their strength and arc stability. However, they will create a fuzzy tip for aluminum, resulting in not properly heating up the metal. 

5. Keep Close Distance Between Electrode and Puddle

The closer you hold the tungsten electrode to the molten aluminum, the more control you will have. TIG welding uses an electric arc to heat the materials, and this arc comes out in a cone shape from the tip of the electrode. 

If you hold the electrode too far away, the arc spreads out too wide. This can cause the aluminum puddle to get too big. When the puddle is too large, the liquid metal may fall out and make holes in your weld. 

Staying close, maybe about 3/16 of an inch or less away, lets you direct the heat better. It helps prevent gaps or excess buildup in the weld that could weaken the joint. Of course, being too close risks accidentally touching the hot electrode to the puddle. But with practice, you can learn to watch the puddle carefully and move the torch precisely for clean, strong aluminum TIG welds.

6. Don’t Direct Feed the Filler Rod

One common mistake that the welders make is holding the rod too close to the welding arc. The arc’s intense heat melts the metal quickly. If the rod touches the arc, it can contaminate the electrode and destabilize the weld.

You must keep a small consistent gap between the electrode and base material for better welding results. Doing this lets the arc melt the base metal first before adding new material. Move the rod slowly into the welding puddle as it forms.

Be careful not to rush. Precision is important for strong aluminum welds. Go slowly to avoid messy results.  

7. Use an AC Polarity

One challenge when TIG welding aluminum is the forming of a thin oxide layer. The good news is that using an AC polarity on your welder can help eliminate this oxide as you work.

With AC polarity, the current flow alternates between positive and negative cycles. This constantly breaks down and removes the oxide so it doesn’t build up. The negative cycle cleans off the layer while the positive one welds the material.

It’s also important to set the balance control on your AC welder to adjust the length of each cycle. For many aluminum materials, lowering the negative cycle time a little can provide extra cleaning of the oxide layer.

8. Use Proper Shielding Gas

Unlike some other welding methods, TIG welding needs a gas to protect the electrode and the aluminum from external contamination. For example, cracks and pores in the weld are the result of hydrogen and nitrogen gasses in the air contaminating the molten aluminum.

Aluminum works best with inert gasses, such as argon or helium, which don’t react with anything. These gasses provide excellent protection and keep everything clean while welding. 

Don’t use carbon dioxide, like you can with MIG welding. In rare cases, a little oxygen or nitrogen can be added for things like stainless steel, but usually you want a pure shielding gas for aluminum.

9. Controlling Heat Input

Aluminum melts at a much lower temperature than other metals, so it’s easy to overheat it. It can cause problems, like melting too much away or warping the material. Fortunately, there are heat control options in TIG welding, making it a great choice for welding precision machining parts.

The best way to control the heat is by adjusting the amperage on your welding machine. Start with a low setting and gradually increase it as needed based on the thickness of the aluminum. Finding that correct setting is key, where it’s hot enough to weld but not too hot. Using a foot pedal also lets you fine tune the amps while welding.

Heatsinks made of copper or aluminum can help too. They absorb extra heat to prevent it from going into the aluminum. 

10. End Your Welding the Right Way

Making it all the way to the end of TIG welding aluminum without issues takes some care. Aluminum expands a lot from heat, so stopping too suddenly can leave an ugly crater behind. But it’s even worse if you see tiny cracks starting there and those cracks might grow over time under stress. To prevent problems, take your time finishing up.

As you work on the last inch or so, slowly dial back the heat from your torch. This lets the metal cool in a more controlled way instead of from hot to cold all at once. Also, keep adding short bead sections right to the very end. Piecing them together seals up the surface.

Conclusion

With practice following these ten tips, your aluminum TIG welding skills will greatly improve. Be patient and focus on consistency with your techniques. Soon, you’ll be creating strong, clean welds that look as good as they perform.

Do you need flawless TIG welding services? Contact Zintilon. We have top industry experts to provide you all types of sheet metal welding and metal fabrication services. 

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