Aluminum is a fine piece of metal with countless benefits and uses.
But can aluminum be welded?
Why, yes you can! However, you can’t weld aluminum in the same way you weld steel alloys.
For one thing, aluminum’s melting point is much lower than other metals, not to mention that it has higher conductivity. Aluminum’s unique properties make it prone to burn-throughs, especially when you’re working with thinner aluminum sheets. Because the feeder wire for aluminum is softer than steel wire, there’s a higher chance of the metal getting tangled up with the feeder.
Simply put, if you want to weld aluminum, you must use sophisticated methods and specialized equipment, not to mention a specific skill-set, to pull it off.
How To Weld Aluminum?
We all know what welding does: to melt two metal pieces and join them. You can carry out this process by using a welding machine. Welding aluminum, however, requires more precision and a stronger bond to be done successfully.
What do I need to weld aluminum?
So, what do you need to weld aluminum successfully? That depends on the arc welding method you’re using. Let’s go over how to weld aluminum for each welding method.
Tungsten Inert Gas (TIG) Welder
A TIG welder uses a tungsten electrode along with an inert gas to provide shielding to the area being welded. TIG welding is the most recommended method for welding aluminum. Why? Because it’s the welding method that not only produces extreme heat but is also able to maintain it for long stretches—something that you need to weld a metal like aluminum. Whether you’re working with thin aluminum sheets or thick ones, TIG welding machines can achieve the precision needed to mold aluminum the right way.
With TIG welding, you need to obtain a filler rod to bond two metal pieces together. That filler rod also needs to use an alloy that’s similar to that of the metal piece you’re welding. As such, you need to use an aluminum filler rod to fuse 2 aluminum pieces. Before you start welding, make sure that the filler rod you’re using is similar in size to that of the tungsten electrode.
Metal Inert Gas (MIG) Welder
Another piece of equipment you can use to weld aluminum is a Metal Inert Gas (MIG) welder, otherwise known as Gas Metal Arc Welder (GMAW). Because MIG welders have high deposition rates, you get faster welding speeds. MIG welders might also require a spool gun to ensure that they’re mechanical wire feeding system is running smoothly. You need to generate more heat when welding aluminum with a MIG welder, which is why it’s always best to use them on thinner aluminum
Just like with TIG welders, MIG welders need a rod that uses an alloy similar to that of the metal piece being welded. When welding aluminum with a MIG welder, you need to use pure argon shielding gas to facilitate the spray transfer process.
Oxy-Acetylene torches use acetylene and oxygen to generate heat. While cheaper than MIG and TIG welders, Oxy-Acetylene Torches are more difficult to control even for experienced welders. Adjusting the heat is also equally difficult, making burn-throughs more common.
The ground clamp is what connects the ground cable to the workpiece. As part of the welding circuitry, the ground clamp ensures that the current can be carried over without overheating.
How to Weld Aluminum
Already have what you need to weld aluminum? Great! Now let’s get to the good stuff. There are many ways to weld aluminum, but only two we would recommend. Those are TIG welding and MIG welding.
Let’s go over the steps for each method one by one.
How to TIG Weld Aluminum
1. Gather your materials
The materials for welding aluminum include:
- TIG (tungsten inert gas) welder. As already mentioned earlier, TIG welder is the ideal choice if you want to achieve precision while welding aluminum. You can buy a TIG welder from a local welding store in your area or your nearest home improvement outlet.
- Aluminum filler rod. You need this tool to fuse two metal pieces. Remember to choose a rod that’s similar in size to your tungsten electrode.
- Can of argon gas. This serves as a shield that will stabilize welder’s arc.
- Protective gear. Choose one that has high resistance to ultraviolet radiation. Long-sleeves are better, obviously. If possible, use one that is made of 100% cotton.
- Safety accessories such as a thick pair of gloves, respirator, heavy welding helmet, and a pair of work boots.
2. Prepare your work area
Aluminum accumulates a thin coating of aluminum oxide over time. As such, you need to clear the aluminum oxide by grinding away at the material with a wire brush or a rough file. Why the need to do this? For starters, melting oxide takes twice the melting temperature as that of aluminum. In other words, you’ll have a hard time melding the joints together if you don’t remove it. You also have to clean the wire brush or rough file beforehand to ensure that it won’t leave metal traces behind.
Next, you need to clean the filler rod with an acetone solution or a scotch bright pad to ensure that it won’t contaminate the aluminum upon use.
Your next step is to make sure that your workpieces are tightened up. You’re bound to struggle with joint gaps if you don’t. To ensure that the workpieces will hold, file them first before clamping them together.
You need to preheat your workpiece to ensure that the welding process becomes smoother. You can put the workpiece in an oven or apply heat on it using a propane torch. The recommended temperature is between 300° Fahrenheit and 400° Fahrenheit. You might also want to put tack welds at both ends of the welding area to better facilitate the preheating process. You can also preheat a thick aluminum sheet when fusing it to a thin one. That way, the welding process can run smoothly and no cold lapping will occur.
3. Practice the welding motion
You need to make sure that you do this correctly, so practice the welding motion before you work on the aluminum. Don’t light up the torch for now. Hold your welder at a 10-degree angle and keep a regular distance (6.4 mm) between the tungsten and the aluminum. Also, make sure the filler is at a 10-degree angle from the tip of the torch. Take care that the torch’s tip and the filler rod don’t make contact or contamination will occur when you start welding.
Now that the welder is in the right position, move it back and forth along the workpiece. To ensure proper motion, move the entire hand instead of your fingers alone.
4. Weld your aluminum
Now before you get to the exciting part, set the amperage of your welder first. For every 0.001-inch of thickness, there should be an equivalent of 1 amp. To be on the safe side, add a few amps to the welder’s amperage settings to serve as a buffer for the preamp output.
Now tap the electrode against the workpiece and draw it back about ⅛ of an inch.
Good so far? Now it’s time to create an electric arc. Do this by pushing the button on your welder. If your torch doesn’t have a button, it should have a foot pedal you can step on instead. If no arc is created, you might need to turn up your amperage. Keep turning it up you see that beautiful arc.
Keep welding until the workpiece creates a puddle that’s almost as wide as your filler’s diameter. When welding aluminum with a MIG, it’s always better to push with your forehand. This is so that the entirety of the weld puddle is covered by the shielding gas. By pushing the weld puddle this way, you can ensure that you’re getting enough shielding gas coverage, reduced contamination, and smooth cleaning action.
Move along the length of the workpiece until all joints are filled up. Next, give your weld several seconds to cool before restarting the weld. Adding some extra filler rod at the beginning of the weld will also help you create a stronger weld. You can then add more filler as you gently push the puddle along the joints.
Are you done welding? Time to stop the arc. Do this by removing your foot off the pedal and then pulling your finger away from the button on the torch.
Next, give the aluminum piece some time to cool off before you test out the finished product.
How to MIG weld aluminum
As already mentioned, using a MIG welder to weld aluminum provides higher deposition rates, which in turn, helps with productivity. But you need sufficient skills, specifically with wire feeding, to pull it off. If you’re feeling worried about getting it right, following the steps below should come a long way in helping you MIG weld your aluminum the right way.
1. Select your welding equipment and tools
When picking a MIG welding equipment, you need to consider the thickness of the aluminum material. For example, a 230-volt welder is enough to weld aluminum with a thickness of 6 mm, or a 115-volt welder to weld aluminum with a thickness of 3 mm.
Next, prepare a shielding gas (preferably pure argon) and your aluminum electrodes. Ideally, the wire should be less than 1 mm in diameter. Check if your regulators are built for CO2. If they are, replace them with ones designed for argon.
2. Use aluminum electrodes
Your electrodes need to have the right thickness for each specific metal. For aluminum, prepare electrodes that have a diameter of 0.035 of an inch. Now the most popular ones are the 4043 and 5356 filler alloys. 4043 is a softer alloy. If you’re concerned about feedability, using the 5356 filler alloy will make the process much smoother for you, though you might need to turn up the current while you’re at it
3. Feed your electrodes with aluminum wire
You can feed your electrodes by using an aluminum feeding kit. Make sure that the contact tips are large enough for the aluminum wires. You may use non-metallic liners to reduce resistance on the wire when it passes through the feeder. Feel free to use U-shaped drive rolls to ensure that the aluminum wire won’t be shaved off. It’s not recommended to use steel feeders or their V-shaped drive rolls for that same reason.
As much as possible, you’d want to avoid “birdnesting” or creating tangling problems with the wire between the drive roll and the liner. If you don’t, you’ll have to cut off the wire and reintroduce new wire to the liner.
4. Keep the MIG welding gun straight
Always keep the gun straight at all times to prevent kinking in the cable while you’re welding. If you don’t, you’ll have a more difficult time feeding the wire. Besides, keeping the gun straight helps in increasing the tension as the wire is being fed into your gloved hand until it’s beyond wire slippage.
4a. Use a spool gun
Since aluminum is more difficult to feed through a liner than steel, using a spool gun might be your best option. Why? Because unlike with typical MIG welders, a spool gun allows you to feed the wire for only a few inches. Sure, the spool gun might be difficult to maneuver, and being able to hold only a pound of a spool of wire electrode is very limiting, but if you can feed aluminum wire without tangling them up every few minutes, then the trade-off is worth it. Better yet, using a spool gun allows you to weld from a power source that is more than 50 feet away.
Welding aluminum can be a challenge at first, but the more you do it, the better your results will be. Aluminum is a great metal, and there are so many beautiful things you can create out of it. Give it the patience and diligence it deserves and you’ll create metalwork that is truly rewarding.