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How to TIG weld aluminium

It seems everyone wants to TIG weld some Aluminium these days and with a little know how and the right equipment, you can too. TIG welding Aluminium is fun, and it also looks cool. Plus you can make some cool projects that you cant make out of steel or where Aluminium is a better option. You could repair your mates tinny or even build your own. Other projects could be a catch can or custom intercooler piping for your car or ute. The list of projects is endless. Aluminium is an excellent material to work with as it is also soft and easy to cut but welding it is not without its challenges. In this post, we are going to run through some of the basics, keeping it simple with the beginner in mind.

What do I need to TIG weld Aluminium?

TIG Welder

To TIG weld Aluminium, you will need a welding power source that has AC current. You can weld Aluminium on DC, but it won't work very well because of the oxide layer that forms on Aluminium. The AC part of the output breaks apart this layer allowing a clean weld. For starters when TIG welding you want to be using DCEN so the TIG torch goes into the Negative port (unless of course you have a machine that can switch the polarity internally) If you have the polarity around the wrong way as most people will default to having the torch in the positive output terminal your tungsten will burn up, and you will have trouble starting the arc when using High Frequency or HF for short.

TIG Torch

You need a TIG torch preferably with a variable amp control or better still a foot pedal. Because Aluminium is a very good conductor of heat, the amps need to be reduced from the beginning where you need more amps to the end where you will need fewer amps. Without this amp control, Aluminium is very difficult to weld, and you will found your self blowing holes or not being able to get enough heat into the work pierce. The TIG torch should use a high flex cable and depending on the amps needed be a 9, 17 or 26 series or WP20 water-cooled. For thin sections up to 90 amps, a 9 series can be used up to 140 a 17 series can be used. If you are welding for long periods above these amps you will need either a 26 series or water-cooled torch otherwise it will get hot and burn out the flex head. There are workarounds such as letting the torch cool and not letting it get too hot this will prolong the life of it. The 26 series is a big torch and can be hard to use, especially when you are starting out. The 20 series water-cooled is the ultimate option as it allows welding up to 300 amps all day and it will not get hot along with being the same size as the 9 series head. However, the lead will have more weight in it than a 9/17 series flex cable. If you are starting out, we recommend using a 17 series this gives you a broad range of amperage and it nice and easy to control.

What gas to use for TIG welding aluminium

For Aluminium like all TIG welding, you will be using 100% argon, or you can use an argon helium mix for better penetration on thicker sections while not needing as many amps. But Helium is expensive, so it is now seldom used unless it has a specific purpose.

Filler Rod

There are two types of filler rod to keep in mind 4043, and 5356 4030 has a higher silicon content, and 5356 has a higher magnesium content. In short, you want to match the filler to the base metal you will be welding. This can get quite technical, so if you want to dive deeper into this, we recommend you do some googling. In general, a good place to start is some 4043 filler which will weld all the six thousand series aluminium.

Base Metal

Get some scrap! The best way to get some offcuts in 2mm, which is a great place to start is any aluminium fab shop or welding workshop. Most of the time they will have some offcuts that will be perfect to start out with you might even score them for free. Otherwise, if you want a heap of coupons buy a full sheet of 6061 and get it cut into strips around 200 x 50, you will get a huge amount out of a sheet and can practice fillet welds, but welds lap joints and more. By the time you weld a full sheet of these coupons, you should have a good handle on it.

Welding Helmet, gloves and other PPE

Protect yourself and your eyes you only get one body! Find yourself a good auto switching welding helmet that is a quality brand such as speedglas being able to see is essential when TIG welding as you could imagine. Get some TIG gloves or rigger gloves, something with good dexterity don't try and use MIG gloves. And always wear a long-sleeved shirt to cover your arms. Any exposed skin will end with you getting burnt. It's a hard lesson to learn.

Preparing the Aluminium to be welded

Nice new Aluminium needs some prep as there will be an oily residue on it. Use acetone to give the metal a good clean and do the same with your filler rod. For heavily oxidised Aluminium that's been left outside give it a good wire brush and acetone. But for new stuff, a quick wipe will usually be sufficient, especially if you are only practicing.

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