With a TIG welder, you have the opportunity to weld metals that are as thin as 26-gauge. That means you can weld even thin sheet metal effectively when choosing this process.
TIG welding provides you with a high-precision, high-quality weld that will pass any inspection. To weld like this on sheet metal does take some practice and practical advice.
Here are some tips that will help you improve your sheet metal welding prowess using the best TIG welders available today.
Best Tips for TIG Welding Sheet Metal
1. Use the 1-for-1 rule whenever you’re welding thin metals.
When estimated the heat input that is required for your project, use the rule that 1 amp should be used for every one-thousandth of an inch of thickness for your metal. Carbon steel performs extremely well with this ratio. If you’re using a nickel-based metal, then reduce the ration by 33%, or 0.67 amps for every one-thousandth of an inch.
You need to make the adjustment for nickel (and stainless steel) because it doesn’t conduct heat as well. If you’re welding magnesium or aluminum, which conduct heat better, the ratio should rise slightly to accommodate.[1]
2. Keep things nice and chill.
If you’re using argon ports, then use copper chill bars with your shielding gas. Both items will draw heat away from where you’re working. Just make sure that you’re not placing the copper in contact with a cobalt alloy, since the zinc in the copper could create problems for you. Use a nickel-plated chill bar with cobalt alloys instead.
3. Shield the backside of your weld.
When you’re welding sheet metal, you should always shield the backside of the weld. That will prevent sugaring (oxidation) from occurring because it reduces the heat input. At the same time, you’ll notice an improvement in the quality of the weld because it eliminates the surface imperfections which would otherwise develop. It will also reduce the risk of cracking when you’re working with a high-fatigue application.
4. Don’t be afraid of the back-step when working with thin metals.
Welders are taught to keep pushing the weld puddle in a single, continuous direction when welding. You go the entire length of the weld in this way. With a thin metal, back-stepping will break up the seam into sections instead, which allows for more heat to be dissipated. You must begin at one position, welding to the left edge, then move to a second position to tie-in the first weld.
When using this process, the length of each step depends upon the length of the joint. As a best practice, back-stepping should never be longer than 2 inches. Thicker sheet metal may allow you to perform a longer weld.
This is not skip welding. You must plot out each weld to tie it in before you begin to weld the first component.
5. Size matters when talking about your cup.
When you’re working with sheet metal and a TIG welding process, you’ll find that most applications ask you to use a #7 cup when working. If you want a high-quality weld on sheet metal, you’re better off using a #15 cup for the work, or larger if you have it. The larger cup offers you better shielding gas coverage over the weld pool and the zone affected by the heat.
Because the heat inputs are reduced, the quality of the bead improves. You’ll notice an improvement in its appearance too, which reduces the amount of work required after the weld to brush away the oxidation.
6. Take advantage of what a glass lens provides.
If you’re welding sheet metal using a TIG torch, then you should always use a glass lens while you work. The lens is a screen which you can insert inside of the cup. It smooths out the gas flow for you, preventing turbulence which could reduce the quality of your bead. Inserting the lens will widen the area of coverage the shielding gas provides too, which allows you to extend the electrode up to 0.75 inches beyond the cup.
That means you have better visibility of the weld area, and you can reach into the corners that you may not otherwise be able to reach.
7. Get to know the gap rule when TIG welding.
When you’re working on sheet metal, you will find that the parts tend to shrink when they’re welding. If you are creating something to a specific dimension, then you must plan ahead to ensure you meet the final specs. You’ll need to determine how much of a pre-gap is required before you begin working, creating parts that are larger than required instead of cutting the sheet metal to size.
You might also find that some sheet metal parts must be cut apart to gain access to a specific location. Then you re-weld the place where you cut. Each new weld you add to the metal will encourage the shrinkage issue.
8. Make sure you’re getting to the point.
When you work with electricity, it is essential that you remember it likes to come off at a point. If your tungsten is sharp, then your arc is going to be focused and controllable. Using a sharp tungsten will allow you to direct heat with greater specificity, which means you can keep higher temperatures away from the parts which don’t require it.
Make sure that you’re using a clean tungsten when working with sheet metal. If your tungsten is contaminated, or it has suffered from balling, then you’ll need to swap out electrodes or grind it clean. Working with contaminated tungsten is a guarantee that you’ll be doing re-work later.
9. Invest into equipment which provides you with strong directional control.
If you’re using a conventional TIG welder that is marketed for at-home applications, there’s a good chance that it cannot pulse any faster than 10 pulses per second (PPS). That is good enough to control your weld puddle up to the edge. Once you reach the edge, however, it takes great skill to prevent the puddle from wicking over, which would melt the edge of the sheet metal.
Lower PPS requires extra metal to conduct heat that an edge cannot provide. If you’re regularly welding sheet metal, then look for a high-pulse DC TIG welder that can reach at least 100 PPS. The faster rate will narrow and stiffen the arc cone, which improves your directional control. Some of the best TIG welders on the market right now that are featured on this page can reach 5,000 PPS if your project requires industrial-level equipment.
10. Make sure your brushes are ready to start working.
You’ll want to maintain separate brushes in your shop to prevent cross-contamination of different metals. It only takes a little bit to create problems when you’re working with sheet metal. Make sure that you write which type of metal is used on the brush itself. Cleaning a weld with a brush loaded with carbon steel particles means your steel won’t be stainless any more. It also means your aluminum would no longer be non-ferrous.
11. Take advantage of your pedal.
TIG welder offer control through a foot pedal or some other remote mechanism. This setup allows welders to regulate their heat output with greater specificity. When you combine the lower power settings that are available on your equipment with the added control, you’ll find that it is a lot easier to weld sheet metal, aluminum, or even thin stainless steel when compared to other welding processes.
Then keep practicing. There is no substitute for experience when you’re using a TIG welder on sheet metal. Combine your work with these tips to improve the overall quality of your work.
