How to Weld Aluminum with a Spool Gun – Learning to Handle the Softer Aluminum

The use of aluminum as a fabrication material has become widespread. It is being used in numerous industries to design various objects, from household items to vehicles. With the widespread use, the need for aluminum welding has also seen a massive boost.

Aluminum attracts industrial designers for a number of reasons. The material is not only extremely light in weight but has exceptional corrosion resistance. For these very reasons, aluminum is fabricated into all sorts of shapes and sizes. However, people who have significant experience with welding would know how challenging it is to weld aluminum.

Challenges of Aluminum Welding

Aluminum welding is not as simple and straightforward as steel welding. Aluminum is much softer than steel, which makes feeding it through a liner extremely difficult. The equipment that is used for aluminum welding should be specifically adapted to handle this softer metal. The machine settings that are used for working with normal steel also need to be adjusted to suit aluminum. Moreover, aluminum wire is so soft that it can easily break or get damaged while it is being fed. This is where a spool gun makes a big difference.

What Is A Spool Gun?

A spool gun is a specialized piece of welding equipment. It is a self-contained gun that is used to feed aluminum wire from spools that are mounted on the gun. These spools weight 1 pound in case of aluminum and are about 4 inches in diameter. The feature that makes spool guns suitable for aluminum welding is that the distance between the wire and the contact tip is fairly reduced, typically less than 12 inches, which makes feeding the soft aluminum much easier.

Spool guns are recommended for softer wires and smaller diameters. It is very convenient and cost-effective for people who frequently switch between aluminum and steel welding.

A Spool Gun versus a Conventional MIG Setup

The primary benefit of using spool guns is that the aluminum wire has to be fed only a short distance as compared to a conventional MIG setup in which the liner is a good 8 to 10 feet long. Pushing aluminum through such a long distance is virtually not doable. The spool gun eliminates this challenge and ensures that aluminum is fed efficiently for welding.

Another benefit that a spool gun has over conventional MIG setup is that 1 pound of aluminum wire is loaded into the gun that ensures a steady supply of the feed. Although a spool gun is comparatively less maneuverable as compared to conventional MIG, it is one of the most efficient ways to go about aluminum welding.

Aluminum Welding

To be successful at aluminum welding, there are certain considerations that are to be taken into account. Other than the length that the aluminum feed has to be pushed through, numerous other factors may impact the smoothness and durability of the aluminum weld. You may find this blog post particularly useful if you’re struggling to find an authentic guide on how to MIG weld aluminum using a spool gun.

Setup Techniques

Aluminum welding is contrastingly different from steel welding. The first and foremost consideration when welding aluminum is bringing about changes in the machine to make it suitable for handling softer aluminum.

Liner

A helically wounded steel liner is used for steel welding, but this type of liner is not suitable for aluminum welding. This is because this type of liner will scratch and scrape shavings off the soft aluminum. When you’re welding aluminum, you’ll need a liner that’s made of nylon or Teflon. These materials reduce friction significantly and prevent the aluminum from getting scratched or shaved off.

Wire Guides

Just like the liner, the wire guides suitable for steel welding need to be changed when you’re welding aluminum. Wire guides made of nylon or Teflon are recommended if you’re looking to reduce the friction and avoid the shaving of the aluminum.

Drive Rolls

The use of drive rolls with a v-shaped groove is a common practice in steel welding. However, you need to have a u-shaped groove in the drive rolls for aluminum welding. This is because drive rolls with u-shaped grooves do not have any sharp edges that might shave or scrap aluminum off. The tension on the drive rolls should also be reduced because aluminum is too soft to withstand this much tension during feeding.

Contact Tips

The contact tips of the welder also have to be changed for aluminum welding. The expansion of aluminum upon heating is greater than steel. Therefore, a nozzle with a larger hole in the contact tip is needed for aluminum welding.

Brake Tension

The brake tension should also be set loosely as compared to what is set for steel welding. This way, lesser force is needed to pull the aluminum wire off the spool.

Gun Cables

The column strength of aluminum, when compared to steel, is much lower. Therefore, the gun should be kept as straight as one possibly can to ensure that the aluminum wire does not tangle and is pushed smoothly through the distance of the liner.

Actual Process

To learn how to MIG weld aluminum using a spool gun with a welder, all you need to do is follow the simple steps listed below:

  • Once you have a spool gun for your MIG welder, you now need to insert the aluminum wire into your spool gun. For this, you first need to uncover the contact tip and canister cover of your spool gun.
  • Take about 8 inches of aluminum wire and clip it. Once done, thread the cable into the gun. Place the spool of aluminum wire inside the canister of the gun and cover it. Do not forget to close the tension arm present at the side of your spool gun.
  • Choose contact tips that are suitable for the diameter of the wire belt. Attach the contact tip to the gun, followed by the installation of the nozzle. Once the two components are in place, your spool gun is ready to be used for aluminum welding.
  • Adjust the tension of the wire to ensure that the speed at which the aluminum wire is being fed is appropriate and consistent. If it is too loose, the speed of aluminum wire feel will not be consistent. You need to adjust the tension to a point where the wire starts to come out smoothly and at a consistent speed.
  • Make sure that you have cleaned the aluminum surface to get rid of any oxides. You can do this by using acetone and a stainless-steel brush.
  • Always maintain an angle of 1 to 15 degrees while you’re at the welding task. This will prevent the weld from looking ugly and sooty after completion.
  • The nozzle of the gun should not touch your base metal. If it does, it might end up burned.
  • Argon gas is required for this process to shield your weld from atmospheric elements. The spool gun should be connected to the positive end of the compartment.

Tips for Aluminum Welding with a Spool Gun

Now that you know how MIG welding for aluminum differs from MIG welding steel and why the regular MIG welder for steel is not suitable for welding aluminum, we can now move on to some useful tips for aluminum welding using a spool gun.

Metal Thickness

MIG welding can be employed for aluminum of a 14-gauge thickness and more. If you wish to weld aluminum of a thickness that’s less than 14-gauge, you might have to use AC TIG or pulsed MIG welding equipment. To make sure that the aluminum feed isn’t wasted through shaving or scraping during feeding, you should always consider the thickness of the aluminum material.

Cleaning

One of the most important tips that will help you with efficient aluminum welding is the cleaning of the material before welding. The oxide layer should be removed from aluminum after degreasing has been done with the help of a stainless-steel wire brush. Make sure that you clean the wire brush before using it on aluminum. Also, the brush should be limited to use on aluminum only.

Right Shielding Gas

For aluminum welding, 100% argon is used as a shielding gas owing to the fact that aluminum is a non-ferrous metal. The shielding is pumped at a flow rate of 20-30 cubic feet/hour.

The Process Used

For MIG welding aluminum, spray transfer is the desired mode of transfer. The reason for this is that it transfers small molten droplets of metal smoothly from the contact tip to the molten weld puddle. Since it is a fairly high-energy transfer mode, it shouldn’t be used on aluminum material thinner than 14 gauge.

Feeding Options

Although we have only discussed feeding aluminum by a spool gun, there are other feeding options as well, including push-pull systems. The spool guns are an excellent option because they can feed soft aluminum efficiently by locating a fairly small weld puddle on a gun that resembles a pistol. Spool guns also eliminate the possibility of bird-nesting. The push-pull systems, on the other hand, are ideal when welding is to be done far away from a power source.

Related Questions

Why is a spool gun recommended for aluminum welding?

A spool gun reduces the distance through which the aluminum has to travel to reach the weld puddle. Since aluminum is a very soft material, it will get scratched or scraped off if it is made to travel a distance as long as in a conventional MIG welder.

Which type of welding is the most suitable for aluminum welding?

Both TIG and MIG welding can be used for aluminum welding. The primary difference is, to MIG weld aluminum, you need an additional component. That component is a spool gun or push-pull system.

Which shielding gas should be used for aluminum welding?

100% argon gas should be used for aluminum welding as aluminum is a non-ferrous metal.


About Pierre Young

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Hey, I'm Pierre Young a qualified AWS Certified Welder. I got into welding in 2009 as a side hustle. Ever since then, I've been doing all kinds of welds - both for business and pleasure. While immersing myself in this wonderful hobby, I've learned from hands-on experience what welding gear works and what doesn't. Welding Headquarters is the site where I share everything I've learned.

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