Although not as widely used as MIG and stick welding, TIG welding is still applied in a variety of manufacturing and repair operations. With the necessary expertise and equipment, TIG welding can solve multiple manufacturing challenges. It is a precise method, which allows for higher quality welds compared with MIG and stick. TIG welding can be performed on a variety of the more difficult metals to work with, including stainless steel, nickel alloys, magnesium, titanium and copper. Aluminum, in particular, is where TIG shines.
“One of the reasons TIG welding is becoming more popular is because of the growth of aluminum in everything from aerospace to automobiles,” says Jason Mahugh, director of engineering and technical service, Forney Industries. “In the last 10 years or so, the price of aluminum has come down significantly and more products are being made of aluminum. Repair shops and fabricators have to learn how to fabricate and weld aluminum. Stick welding aluminum is terrible at best and MIG welding aluminum is difficult. TIG welding is excellent for aluminum. Anyone would choose TIG for aluminum over MIG or stick – if they could.”
The TIG welding process is complex. It takes an increased level of skill and knowledge to perform over MIG and stick welding. It can be particularly intimidating for beginners and smaller shops.
“It’s difficult to do, and there is a bit of a long learning curve,” Mahugh says. “You’ve got to put in some hood time. The minimum time to learn to TIG weld is probably around 40 hours and that’s just becoming OK at it. I can teach someone to MIG weld in a couple of hours and stick weld in about 6 or 8 hours and they would be passable. Also, TIG welding is something you need to do on a fairly regular basis. If you don’t TIG weld a few times a month, you’re going to you lose that skill. If I have to TIG weld something, I actually practice for an hour or so to get my feel again. I wouldn’t do that with MIG or stick.”
Specifically, the operator must hold the welding torch in one hand and feed a filler rod into the weld puddle with the other hand. The tungsten electrode delivers the current to the welding arc, and the tungsten and weld puddle are protected and cooled with an inert gas, typically argon. The operator uses a foot-operated amperage control pedal to slowly initiate and reduce the heat after the weld is complete.
“Controlling those three at once isn’t easy,” Mahugh says. “At the same time, you’re also trying to control how the puddle is flowing and making sure you’re getting good penetration. With TIG welding, you have about six or seven things going on at one time, and that can be difficult to control.”
Reasons why
The greatest benefit TIG welding offers is precise heat control and penetration. Heat control is important because typically the base material is 1/8 in. or thinner with TIG welding. MIG and stick welding typically would be used for thicker materials where heat control is not as important.
Another benefit is no spatter creation. “If you’re producing spatter while TIG welding, you are doing something wrong,” Mahugh says.
With MIG and stick welding, the arc is between the filler metal and the base metal, which naturally produces more spatter. With TIG welding, the arc is between the tungsten electrode and the base metal, so it doesn’t create spatter. This is the same reason there tends to be fewer inclusions, like porosity, with TIG welding.
TIG welding works well in all positions, including overhead work. The puddle control prevents the molten metal from dripping down. Another nice feature of TIG welding is that it produces fewer fumes.
TIG welding does have some drawbacks, however. For starters, it’s slow because of the low deposition rate and the precise heat control.
“I can MIG weld 10 times faster and stick weld five or six times faster,” Mahugh notes.
TIG welding equipment and parameter controls are also more complicated than the equipment that’s used for MIG and stick welding.
“You have to know how to set the machine properly,” Mahugh says. “With stick welding, you typically have one parameter to change, which is amperage. For more heat, turn it up, for less heat, turn it down. With MIG welding, you have two parameters to control, wire feed speed and voltage. With TIG welding, I’m controlling anywhere from five to 12 parameters. If you don’t understand how those parameters work, you can definitely create some poor welds.
“In the last few years, I have noticed engineers are focusing on making TIG welding machines easier, especially for beginners,” he adds. “By removing some of the complexity around those parameters, the operator is now concerned with maybe only four or five parameters instead of 10 or 12.”
That is a design philosophy at Forney Industries, as well. The company focuses on making things easy to use and shortening the learning curve.
High costs are another drawback to TIG. The equipment tends to be more expensive than MIG or stick welding equipment and inert gas is required. (MIG and stick welding can use reactive gases. The higher skill and amount of knowledge required by the welder can result in higher labor costs, as well.
Best practices
That higher skill and knowledge comes in handy when it comes to avoiding TIG welding mistakes. For instance, experienced TIG welders would know not to use MIG welding gases when TIG welding.
“Argon is the go-to gas for TIG welding,” Mahugh says. “You need an inert, or nonreactive, shielding gas to protect the tungsten from the atmosphere. MIG welding sometimes uses a little bit of a reactive gas, say argon mixed with something else, but in TIG welding, that would be disastrous. Helium is an inert gas and can be mixed with the argon to get a little bit of extra heat to help with penetration, but that is about it as far as TIG gases are concerned.”
Another thing to keep in mind is that TIG welding should only be performed on clean metals to avoid poor looking welds and a lot of frustration.
“I like to clean the filler metal, as well,” Mahugh adds. “I use an alcohol-based wipe to wipe down to my filler metal, make sure make my tungsten is perfect and then make sure my base metal is nice and clean. I usually wipe down the base first and then remove the oxide layer. If you don’t, and there’s a little bit of dirt or oil, you can actually wire brush it right down to the base metal when removing the oxide and then it becomes a problem. So I clean my base metal first, then remove my oxide layer, then I go to town.”
As for polarity, proper TIG welding on aluminum requires an AC output machine. For welding on steel or stainless steel only, DC output is fine.
“On an AC machine, I want to be able to control pulse, frequency and balance, which is polarity,” Mahugh says. “Those are the minimum parameters along with amperage. If you’re going to TIG weld on stainless, all you need is a DC machine, and I prefer to have some pulse control especially when working on thin material. But if you’re buying a DC TIG welding machine to weld aluminum, that is not going to happen.”
Mahugh’s final bit of advice is to choose your filler metal carefully, particularly with aluminum and stainless steel.
“Be sure to choose the right one for the base metal or you will absolutely get cracking or other problems,” he says. “There are hundreds of filler metals and five or 10 of those are the most common. It can get pretty tricky. That is where you get a welding engineer involved, if you have access to one. If not, there are some nice guide charts available from the filler metal manufacturers.”
