Alu TIG - How to TIG Weld Aluminum Masterclass video

NEW!!  Free Guide on How to TIG Weld Aluminum

Clean your metal (if it needs cleaning)
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Most welding textbooks state that you absolutely must clean all aluminum prior to welding. 

This ideology simply does not match up with real world practice. 

While I do agree that if aluminum is dirty, it should be cleaned using a method that is appropriate for the intended result. 

But there are many situations that do not permit wire brush marks on the finished product and brand new clean aluminum does not require wire brushing or other cleaning anyway.

Aluminum should be clean prior to welding but that does not always mean it needs wire brushing, abrasives, or other type of cleaning. 

Often a simple wipe down with a solvent like acetone is sufficient and sometimes that is not even required. It depends on the most wanted result. An aerospace weld test that will be X-ray tested has different requirements than a tread plate truck box.

Get Your AC settings Dialed in
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The main 2 settings For TIG welding aluminum are 

1. AC balance

2. AC frequency

Some tig welding machines have many more settings like waveforms but the main 2 settings that make the most difference are ac balance ad ac frequency.

The ac balance setting adjusts the level of cleaning action and should be set with enough cleaning to provide a clean puddle that is free from dots of oxides.

AC frequency is more of a preference setting but a good starting point for machines that have this setting is 60-100 hz.

Use the Right Tungsten type, diameter and Prep
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The best 3 choices of tungsten For TIG welding aluminum are 2% lanthanated (blue), CK LaYZr (chartreuse), and E3(purple).

A 3/32” diameter 2% lanthanated usually works well up to around 200 amps or 3/16” thick aluminum. 

There are several ways to prep the tungsten tip For TIG welding aluminum but a blunt tapered tip  usually works fine. If you find that the tip mis shapes at a certain amperage, you can round a freshly tapered tip a bit using a high cleaning setting on the ac balance or by switching polarity and rounding the tip on DCEP just a bit.

Use the Right Cup & gas flow rates

There are a lot of opinions on what cup is best For TIG welding aluminum. Some people prefer standard collet body cups while others prefer gas lens cups. You can easily browse instagram and see awesome looking welds done with both collet body cups and gas lens cups.

It's mostly the weldor behind the hood making the biggest difference ..not the Cup

However, I do recommend using a #4-8 size cup for aluminum.

Cups larger than #8 tend to create a lot of extra cleaning action and wasted energy in all those ions pinging around.

The most common and versatile shielding gas For TIG welding is pure argon.  For aluminum 1/8” and thicker, an argon helium mix or specialty gas like STARGON AL from praxair can be helpful.

Flow rates depend mostly on cup size and a good rule of thumb is 2 to 3 CFH per cup size.  Using a factor of 2.5 CFH here is a down and dirty chart for argon flow rates for each cup size

Argon Flow rate chart based on 2.5 CFH per cup size

What amperage do I use for TIG welding aluminum?

Amperage For TIG welding aluminum depends on several factors like thickness of metal, joint type, chill factor, shielding gas used, and a few other factors. While there is no way to accurately list the amperage that will work on every situation a rule of thumb is 1.2 amps per one thousandths of thickness up to around .190” thickness. 

After that the rule starts to drift a lot.  But when you are using a foot pedal, you might want to set the machine a bit higher and just control the amperage using the foot control.

Arc length and angle

Arc length and torch angle are two important variables For TIG welding in general but especially with aluminum. while a tight arc length helps, You may learn that lengthening the arc length while dabbing filler metal prevents contaminating the tungsten.  The puddle tends to grow in height while you add filler rod on most welds and sometimes that causes the electrode to sputter in the puddle and get contaminated. A simple adjustment in technique can save you lots of time cleaning tungsten.  torch angle should be limited to around 15-20degrees but torch angle can be very forgiving if arc length is good.

How do I know what Filler Rod to use?

Here is a great page on aluminum filler metal selection

4043 and 5356 are the 2 most frequently used filler metals for tig welding aluminum and will work for many different applications.

So how do you know which one will work better for the job at hand?

And when would other aluminum filler rods like 4047 or 4943 or other filler metal would be a better choice?

First lets use one of the most welded aluminum alloys…6061 aluminum as the first example.

6061 can be welded with either 4043 or 5356 and a few other filler rods.

But filler metal choice for 6061 aluminum depends on a few key factors.

There could be other questions that guide your choice but here are 3 main questions to answer 

Will the part be anodized after welding? 

If the part will be anodized, realize that welds made with 4043 won’t respond well and will be dark.

Will the part be subjected to temperatures above 150f during service? 

Welds made with 5356 can be crack sensitive when exposed to temperatures above 150F.

Is the weld a fillet weld or butt weld?

while 4043 flows better, 5356 filler metal is stronger and tends to hold up better for fillet  welds.

Filler Rod Feeding and Timing

Addition of filler rod at the rightly timed intervals is how you get uniformity. when you are first learning you should strive to add the filler rod about once per second and you can easily count seconds in your mind.  Thousand one…thousand two…thousand three.  

As you get more seat time and become more proficient your travel speed will probably get faster in most cases but dont be in a hurry to increase travel speed while you are learning.  Speed will come soon enough. Concentrate on uniformity before speed.

Most modern inverters have pulse capability.  while pulse is not necessary for tig welding aluminum, a Pulse setting of 1 pulse per second with background of around 50% and pulse width of 50% can help you develop your filler metal timing.

Pedal control or torch amp control

In the USA foot pedals are common.  But torch mounted amperage controls have their place too and can help a lot for certain situations like large projects where you have to kick the pedal around to make a bunch of tack welds.  A torch mounted amperage control comes in handy for those situations. But for situations where you need the utmost precision and can not afford the slightest torch movement while adjusting amperage, a foot pedal rules.

Practice drills for Building Skill for beginners

I am personally a big fan of practice drills.  It makes no sense to try to weld lap joints, corner joints, and tee joints if you can’t weld a uniform bead yet.

The main practice drill I suggest is what I like to call the “aluminum drill” where you pad beads on a piece of aluminum that is around 1/8” thick.

It is the best and cheapest practice you can get and it even works better if you alternated welding on aluminum and carbon steel.  

The reason is because by alternating metals, the brain doesn’t get complacent and learning plateaus are avoided.

Troubleshooting

Troubleshooting requires a good working knowledge of process fundamentals.

Taking the time to Learn the fundamentals of tig welding aluminum will pay dividends and help you diagnose and troubleshoot problems.

We know that all aluminum has an oxide layer that is broken thru by the electrode positive part of the alternating current. 

We call that cleaning action.

We also know that the cleaning action tends to only go where there is argon shielding.

We also know that aluminum needs to be clean before welding to prevent mixing in any contamination like coatings, oil, grease, paint, etc.

We also know that an electrode that is contaminated with aluminum will not make a clean weld.

So when things start going wrong tig welding aluminum,

Make sure the metal is clean, make sure the tungsten is clean, and look Make sure argon flow rates and AC balance settings are correct.