Aluminum is a relatively soft metal in its pure shape. It has various uses but requires alloying to enhance its structural stability. In addition, since the characteristics of aluminum differ substantially from steel, dealing with the material might bring out some issues such as distortion and heat input sensitivity.
Despite these obstacles, MIG welding aluminum isn't precisely rocket science as long as you have the suitable equipment and use the appropriate method.
What Makes Aluminum Welding Complicated?
Aluminum is an excellent thermal conductor that quickly distributes heat that might lead to undesirable deformation or fracture of the object. In addition, aluminum is famous for its blow-through susceptibility, where the metal breaks down under a high-pressure arc.
Also, when exposed to the environment, aluminum oxidizes quite fast, which lends it a critical capacity to resist corrosion and makes it necessary to clean your aluminum workpiece thoroughly before striking an arc.
What to Consider Before You MIG Weld Aluminum
You can use a MIG welder on aluminum with a spool gun. However, it's a frantic procedure that generates a lot of sparks. To get the best results, take these things into consideration before beginning.
Working with a Spool Gun
A spool gun reduces the wire’s travel distance to the weld pool. You need a spool gun because the aluminum wire is considerably softer than steel wire and will not go through the machine as smoothly.
Examine your welder's settings for how to convert to a spool gun. First, you must unplug your MIG gun and reconnect it to your spool gun. Typically, the machine will have a button that you press to notify the machine that you are switching welding modes.
Choosing the MIG Wire
To weld metal, you'll need an aluminum wire, usually the alloys 4043, 5356, and 5554. Make sure the wire grade matches the grade of aluminum you're welding with and that you're familiar with your alloys. For example, 5356 can withstand high amounts of stress. Meanwhile, 4043 has better wetting action and is widely compatible with other aluminum alloys.
Cleaning the Work Metal
The metal needs to be clean when you’re welding aluminum. Remove any oil or impurities from the surface, including the thin coating of aluminum oxide that rests on the metal's surface. We advise using a stainless steel wire brush to scrub the workpiece metal.
Controlling the Speed
Because aluminum has a far more excellent conductivity than steel, it requires higher voltage settings. As such, you'll need to adjust the wire speed settings accordingly to avoid messing up your weld. Instead of tugging the bead, use a pushing motion.
Getting the Shielding Gas
Pure argon or a combination of argon and helium is a good shielding gas in MIG welding metal. Despite the high cost and low efficiency of helium, it is necessary if you're working on thicker metals, which require more heat. Because the CO2 will oxidize the aluminum, you should not utilize your CO2 gas cylinder or combine it with argon for MIG welding metal.
How to MIG Weld Aluminum
You can MIG weld aluminum if you configure your equipment (e.g., a plasma cutter or multiprocess welder) to direct current and reverse polarity. You can also perform this welding in any position; however, if you’re not an experienced welder, avoid more difficult positions.
Before you start the welding process, ensure that you have a sufficient tank of shielding gas. Plain argon gas is suitable since it produces a very smooth, steady arc. However, an argon/helium mixture will also be a great alternative.
The significant benefit of argon/helium gas is in its greater penetration capacity, although it warrants caution when working with thinner workpieces. If you opt to use an aluminum MIG welding gas that is a mixture of both, 75-percent helium and 25-percent argon should offer you the best of both worlds.
To prevent jamming the machine with the filler wire, a push–pull mechanism of wire feeding might be more suitable. If you're working in confined locations or awkward positions, a spool gun should be your first choice.
First, strike the electrode an inch from your weld. Afterward, swiftly move it to the starting point of your weld. As you progress along the weld, use a string bead approach without modifying the angle of the electrode. It would be best if you were moving quite rapidly, but try to pick up the pace as you reach the end of the weld. Doing this will limit the amount of cracking by reducing the size of the weld pool. Also, when welding horizontally, aim the gun upwards.
Can you weld aluminum with a MIG welder? Yes, but it is clear that aluminum welding is more challenging than other materials like steel. Nonetheless, all of the extra time and money spent on specialized equipment will pay off since the results will look and feel truly professional. In addition, aluminum is a terrific material to deal with. That’s why it's a must-have talent for anybody serious about welding.
- Can you weld aluminum with a flux-core MIG welder?
The short answer is no. It's not going to turn out well. To begin with, it is difficult at best to MIG weld aluminum. You can occasionally get away with passing the aluminum wire through your gun if it's in a good straight run and you have a slick liner, but in general, you'll need a spool gun.
For the shielding gas, you'll need 100-percent argon. With flux, you're probably running DC electrode negative, which is excellent because it allows for light penetration, but aluminum generates an oxide that you must remove using DC electrode positive.
2. Can you weld aluminum with a gasless MIG welder?
Here too, the short answer is no. Because the only filler available for aluminum is solid, outside shielding—often argon gas—is necessary.