The Elegant Weld
- October 4, 2016
TIG welding is precise, clean, and even efficient
When I was first introduced to TIG welding, it was explained to me that this was the “Cadillac” of welding. It was a precise, elegant, high end welding process only used by a select few. These claims were a bit overblown, but the fact that TIG welding is precise and elegant is very true. “Fabricators choose the TIG welding process when they need to precisely control fusion and weld bead placement, size and appearance,” says Tom Wermert, senior brand manager for ESAB.
“Numerous welding codes, especially those related to process piping applications, as well as aerospace and motorsports applications, specify the TIG process because a properly executive TIG weld is mostly likely to be a sound weld.”
A great benefit of TIG welding is its ability to weld just about any metal with only a few simple adjustments to the power source. Mild steel, stainless, steel, aluminum, brass, bronze, tungsten–it will do it all.
TIG welding, however, is a slower process. “From all the welding processes we have, TIG welding is traditionally noted as being a slower welding process,” says Andrew Pfaller, CWI, product manager at Miller Welds. “However it does have its own advantages being a more esthetically pleasing process. If done properly, there is no smoke, there are no sparks, and there will be no spatter coming off the process. From a purity process, for food and beverage production, for nuclear power plants, you don’t want the sparks and spatter getting in to contaminate the system or the surrounding are. TIG is generally used to benefit the nice looking welds and where the welds have to have a high purity application that they can’t have and have to blend in with the surrounding material very nicely.” The quality and esthetics of the weld are paramount in TIG welding. High end bicycles will have their aluminum frames welded with TIG. “One of the advantages of TIG welding is the ability to give the weld a very precise, ‘stacked dimes’ appearance,” says Scott Stanley, national marketing manager at Lincoln Electric Co. of Canada.
For the most part, TIG welding is performed manually with a hand held torch, with the tungsten electrode, in one hand, a rod of filler metal in the other and the power controlled by a foot controller or a power setting on the torch itself. It is partly a ballet, with the operator constantly moving the tungsten torch along the workpiece while simultaneously adjusting the power and adding filler material to the puddle.
Making this process more efficient is often a question of better equipment. “TIG welding has changed quite a bit in the past 10 or 15 years,” says Pfaller. “Twenty years ago, when the majority of the industry was using transformer based welding power sources, when they were welding aluminum, they were using an AC wave form that welded at 60 Hertz, or whatever the wall power was.” Transformer based TIG welders passed the frequency of the electricity through to the torch resulting in a less efficient welding process. “With the new inverter technologies in the market today we generally use 100 or 120 hertz output. Most of our products here at Miller are 120 hertz as a factory setting. And what that does is that it focuses the arc into a smaller area.”
Concentrating more heat into a smaller area makes the weld more precise, gives better penetration and is more efficient. “We can drive more heat into a smaller area, if we are trying to achieve the same amount of penetration in the workpiece that means we can get a faster travel speed if we are making a narrower weld at the same penetration,” he says. “With the newer inverter power sources, whether it is with aluminum or stainless steel, we can increase the productivity for hand held applications, somewhere in the area of 10 to 15 per cent and in automated applications you might see double or triple the travel speed as compare to a hand held operation.”
Technique can also help make TIG welding more efficient. “Appropriately preparing the base material before welding can improve TIG efficiency two ways. The first is to incorporate a good pre-weld cleaning procedure into standard production practices in an effort to prevent potential weld quality issues like porosity and lack of fusion. The second is to use the pre-weld cleaning practices to troubleshoot issues if they occur,” said Rob Krause, technical services manager, AlcoTec Wire Corp. “Yes, it is possible to make a quality weld on new, properly stored base material, and yes, we’ve heard all the excuses such as 'I don’t have time for all that weld prep’ and I’ve never done any prep and none of my welds have failed’ top the list. That said, if you’re four stories up on an aluminum catwalk or towing a trailer with a heavy load, there’s a certain comfort factor obtained by knowing the welding professional adhered to well-accepted procedures.”
When using hand held TIG, placing the object in a positioner can increase efficiency. “Many pipe shops or fab shops will, when working on round items, actually clamp the part into a positioner and sit there and hold the torch and have the part spin as opposed to having to weld, stop, spin the part, weld and so on. So they can do one continuous weld and reduce the down time that way,” says Pfaller. “It gives them a more consistent weld because they will always weld in the same position. So from a quality perspective and productivity they see gains there.” SMT