Aluminum is undoubtedly one of the more difficult materials to weld. Due to the difficult nature, Forney receives a surplus of questions regarding aluminum welding. Read on to discover more about TIG welding aluminum.
Let’s be honest, aluminum welding can be a pain in the butt when it comes to making aesthetically pleasing welds. However, when it’s done correctly it can make your project last longer, reduce weight, eliminate distortion and make some really beautiful welds.
Generally, two processes are used for aluminum welding: GTAW (TIG) and GMAW (MIG). Most welders in the business will say TIG is the better option for welding aluminum because it allows for better results on lighter gauge materials.
When done correctly, TIG welding aluminum can produce quality welds. This process also allows more control over tricky welding variables like heat, penetration and overall aesthetics. In addition to those benefits, aluminum TIG welding makes working with thinner materials a breeze!
Welding aluminum takes a lot of time and patience, so it’s more common in applications where efficiency isn’t as important as quality and appearance. But once you get it down, rest assured you will have some great looking welds.
Now that you know the basics, here are more helpful tips to help you master aluminum!
Clean Your Materials
Those who aren’t familiar with welding aluminum might not realize that this material generates an oxide layer. If the oxide layer is left on the surface of the aluminum, it could prevent adequate penetration. To avoid this, you can clean the oxide layer with a dedicated stainless-steel wire brush or brass brush before you begin welding. To avoid contamination use the same brush for every aluminum project (or thoroughly clean the brush you use), remember to only clean in one direction.
Hand and Torch Placement
When TIG welding aluminum, it’s best to hold the torch by bracing it from your wrist to the tip of your pinky finger. Placing your hand flat against the table, keep the torch steady and move in a forward moving position. You only need a slight backwards tilt to the torch.
Use the Correct Polarity
Even after you clean your material, the oxide layer immediately begins to reform which can block affect your weld quality. That’s why it’s crucial you use alternating current (AC) polarity when TIG welding aluminum. This polarity provides a cleaning action that helps remove and break up the oxide layer on aluminum, creating a nice flowing weld puddle.
Use a Shorter Arc Length
It’s important to use a shorter arc length while welding aluminum, so that you can help localize or focus the heat to a small area.
Add Filler Metal
If you add filler metal to your weld when working with aluminum it’s easier to achieve that “stacked-dimes” look on a weld. Adding more filler rod causes a cooling effect on the backside of the weld puddle. This effect adds a smooth appearance to the weld, causing it to look like stacked dimes.
Storing your base materials and filler metals properly can help avoid contamination. If possible, store your sheets of aluminum inside. If you must store your materials outside, stand sheets of aluminum vertically to prevent the entrapment of water.
So many TIG welding issues can be blamed on contamination whether from the atmosphere or environment. To avoid atmosphere contamination, use gas lines or hoses in new or good conditions and make sure air or atmosphere isn’t sneaking into the lines.
Adjust the Balance Control
When you have the right balance control, you can adjust the ratio between an EN (electrode-negative) and EP (electrode-positive) current. A good rule of thumb is about 70% electrode-negative. The EN current is considered the welding side of the AC waveform, whereas EP is where the cleaning or oxide removal occurs. balance control simply allows you to adjust the ratio between the two polarities in response to what you’re seeing in the weld puddle. If you notice your weld is peppering (when small black flecks appear in your weld puddle), it’s a good indication that your balance control is not set properly. If this does occur, try turning the balance control down so there is less EN.
Set the AC Output Frequency
The higher the AC output frequency, the more stable or focused your arc is. Turning down the AC output frequency to 80 or 90 Hz can provide a wider arc cone, which can be helpful when welding corner joint located in a difficult position.
Believe it or not, preheating your aluminum work piece can help avoid weld cracking. Preheat can help slow the cooling rate and solidification. Typical preheats are in the 100-200 degree range. The temperature of your material should not exceed about 230°F. If you place tack welds at the beginning and end of your welding area it might help the preheating process.
GTAW stands for gas tungsten arc welding, meaning that TIG welding requires the use of tungsten electrodes. Older transformer machines used pure tungsten, although nowadays newer inverter machines usually recommend 2% ceriated or 2% lanthanated. Find out more information about tungsten here.
You should keep two words in mind when aluminum welding; fast and hot. If your travel speed is too slow you could have excessive burn through or melt through, especially if you’re working with a thinner gauge aluminum sheet.
A weaving technique can be used with many base metals, but it should not be used with aluminum. A better alternative is a stringer bead. A stringer bead helps with proper penetration and fusion. Be sure to use higher heat inputs and a fast travel speed to stay in front of the puddle, especially when you’re TIG welding.
The size of your nozzle can affect a weld. If your weld has porosity try a gas lens, or a larger cup. This will help prevent contamination and improve gas flow.
Safety is a Priority
Like welding any other material, aluminum welding comes with some risks. To stay protected, make certain you’re wearing a welding helmet, safety glasses, a welding jacket or sleeves and welding gloves. Aluminum is a highly reflective material, and it takes a great amount of energy to weld. This can cause the arc to have an even higher intensity, and possibly burn your skin.
With the help of these guidelines and a little bit of practice aluminum welding can be just as simple as steel welding. Now get out there and show aluminum who’s boss!