There are several types of metals that can be TIG welded, but aluminum is the metal most commonly used with this process. It is usually more efficient when metals of small thickness are used. Along those lines, aluminum is a soft and lightweight metal that isn’t very strong and can be easily be forged, machined, cast, formed, and welded.
It’s also suitable when used on low-temperature applications and can be readily joined by various processes, such as welding, soldering, and brazing. However, TIG welding aluminum is considered to be one of the most versatile type of welding that is efficient for professional welders. This is mostly because TIG welding offers precise results, which is a big plus for when you’re welding aluminum.
To TIG weld aluminum, you’ll need some specific equipment, which we cover in the next section.
Equipment you need
You are required to have a TIG welder. This can be difficult, however, since these welders tend to be fairly expensive. Even buying one of the cheaper units requires some decent cash. Although, keep in mind that these more expensive units are well worth the price and are usually high quality, which makes your life a whole lot easier when welding. These welders are able to make neatly welded joints as compared to the poor quality produced by the cheaper units, which in most cases are charred and poorly formed.
It really helps if the welder has a foot control for current; this is to ensure the heat is kept constant as it moves towards the weld from the electrode. Using an alternating current (AC) will help you get better results when used at high frequency.
Having a torch nozzle is also an essential element to be used on aluminum. Using a wide heat range input is needed as you move at different metal size thickness. Argon gas is also needed to ensure that molten metal is shielded from outside air to prevent contamination.
Another item you need is an aluminum-welding rod, which can be hard to decide on which type. We’d highly recommended the 4403 type of alloy, which will enable you to deliver better results.
For cleaning the work surfaces, you keep a stainless steel brush around which should be dedicated only for use on aluminum and nothing else. This is to prevent contamination. Along these same lines, you should also keep a squirt bottle handy which should always have water in it. This will be useful for cleaning the work surface and cooling the metal after welding.
For safety purposes, it is crucial to have good welding gloves to prevent getting painful blisters. In addition, having a welding helmet that is in good condition. I can’t tell you how annoying it is to have an old helmet that is always falling off your head all the time. Make sure the helmet has a good size window for you to easily see the working area through. Ones that are too small can make it hard to see what you’re doing, as well as your surroudnings, which is important for on-site jobs in busy work areas.
First, cleaning the aluminum is vital no matter how it may look initially, either clean or dirty. If you’re arc starts wandering, then you know you have dirty aluminum. The arc might also start curling away from the edges when trying to fix two pieces or may even have trouble with your filler when trying to blend it in the puddle.
To fix this, start by spraying the metal with acetone to get rid of any excess residue, and then rinse with clean water to remove the acetone. You should ensure that every bit of the aluminum is completely dry before starting to weld again. Also, don’t forget about your stainless steel brush. Use it to scrub the aluminum until it becomes shiny.
Before you start welding, I’d recommend clamping your work to an aluminum heat sink, allowing you to manage higher heat transmissions during welding. At this time it’s also a good idea to make the parts fit together better by using a die grinder or file, thus making the weld joint much easier to deal with.
Another common annoyance is cracking. To prevent it, I’d advise you to preheat the work piece. This way the metal doesn’t experience a huge swing in temperatures, which is a big cause of cracking.
Make sure you monitor your tungsten gas closely and make adjustments any time you see evidence of the arc starting to become unstable. It’s important to fit all parts of the TIG welder tightly leaving no gaps. This will help prevent you from applying heat on only one side of the metal. Since heat from these welders are localized, any gaps in the shielding gas will lead to metal pooling to the side that the heat is being applied, which then leaves other parts of the metal in a solid state and giving you a poor quality weld.
On your machine’s main amperage control, set the desired amperage and start the arc by pressing the torch. It is recommendable to set the amperage a bit higher than that which you’d expected due to the high thermal conductivity of aluminum. This is much different than with steel, so most beginners have to learn this through experience.
To start the arc, press down the foot pedal about half way. This will ensure that the set amperage travels to the head of the torch and tones it. To actually start the weld, extend the tungsten electrode to a length that is less than the torch nozzle diameter. Thereafter, the electrode tip should be tapped to your work piece and then pulled away only about 3 milimeters. This tapping will create the electrical arc.
After this, start creating the puddle with your arc. You should melt your work piece until you get an adequate puddle size. To actually fill the joint, add some filler rod and move to the other remaining portion of the weld. Repeat the same process until you properly weld the entire joint. Push the puddle forward slowly, ensuring the torch creates a joint and as you do this, you need to be adding filler to the puddle. Maintaining an even pace will help you keep the size of your puddle consistent, giving you a better looking weld.
The Dos and Don’ts
It is vital to clean the aluminum and the weld surface before starting the TIG welding. Make sure you’re very thorough with this. Working on an impure or dirty surface will hinder you from getting the desired outcome. The tungsten should be grinded well and be similar to the tip of a pencil when finished. To keep the tungsten in position, use some gas lens, this will enable you deal with current transfers.
When converting from alternating current to direct current it is important to use an inverter power source.
You should avoid subjecting your welding work to windy conditions. This will help prevent cases of porosity and pinholes on your weld. Using too much torch gas when dealing with aluminum A/C can be dangerous and it is advisable to minimize its use for your own safety.
Additionally, welding without safety equipment should be avoided at all costs to prevent damages. I’ve seen cases where UV radiation from TIG welding acutally burned the operator’s skin, with blisters and peeling skin. It doesn’t take long to get these kinds of burns, so always make sure you wear long-sleeve clothing at all times.
Aluminum TIG welding has a lot of advantages, ranging from no slag, to no spotter and high efficiency. Additionally this method gives very high quality welds, which is really what we’re all striving for at the end of the day.