Experienced welders know that without the right information, it's easy to sacrifice quality, lose time, and generally become frustrated with gas tungsten arc welding (GTAW), also know as TIG welding. For novices that statement is even truer. So while there's merit in learning to weld by trial and error, if you want to move toward precision GTAW, getting answers to these 10 very basic questions can help ease the transition and get you well on your way to learning how to properly TIG weld. Stay tuned and follow up on this story as we dive deeper into the world of TIG. For more information, contact the companies listed in the Source Box.
1. Should you use an air-cooled or water-cooled torch?
For low-amperage applications, an air-cooled torch cooled by shielding gas works well. These torches are simple to operate and require minimal setup. For high-amperage applications you can still use an air-cooled torch, but the cable and torch must be much heavier and may be cumbersome to manipulate. A water-cooled torch, which circulates water through the torch and cable, works equally well but requires additional equipment and maintenance. These torches use clean, deionized water with filters that prevent contaminants from entering the cooling supply or the inner-diameter tube of the torch. You also may need to use additives to prevent algae growth.
Whether you choose a water-cooled system depends on your willingness to invest in additional equipment, as well as additional time and money for maintenance. Many welders, however, prefer these systems because the smaller torch configuration provides better maneuverability and reduces operator fatigue.
2. What is the proper procedure for cleaning base metals?
The base metal should be free of all contaminants, including dirt, paint, and oil. Wipe the base metal with a cloth or scrape it with a wire brush dedicated for use on a particular material. Before welding on aluminum, in particular, you need to remove oxides with a stainless steel brush manually; using a power brush is not recommended, as it can re-embed contaminants into the metal. You can also use a caustic solution to clean aluminum. If you are considering using this method, your local welding distributor is the best resource to provide you with product options. You can also discuss several scraping methods with your distributor if you do not want to use chemicals.
3. When should you use a gas lens?
A gas lens should be used when your application requires increased shielding gas coverage. The gas lens reduces turbulence and provides lengthier, undisturbed gas flow and allows you to move the nozzle farther away from the workpiece while still keeping the arc or weld puddle in view. Using a larger nozzle with a gas lens (which consequently produces a larger blanket of shielding gas) can help when welding on materials such as stainless steel and titanium. A gas lens also allows more direct and broader gas coverage on tight joints, such as an inside corner, where access can be limited. In critical applications that have potential for atmospheric contamination, a gas lens can help to reduce the likelihood of weld discontinuities.
4. What are the causes of an unstable arc, and how can you remedy them?
Using the wrong size tungsten, whether in AC or DC applications, is one of the more common causes of an unstable arc. If the tungsten is too large for the amperage, the arc may rotate around the end of the tungsten. Conversely, if the tungsten is too small for the amperage, the current can melt the electrode and cause an erratic arc. To remedy either of these conditions, match your welding current to the tungsten size recommended by the manufacturer. Contaminated tungsten (caused by debris on the base metal, oxidation from inadequate shielding gas, or gas impurities from a leak) also can cause an unstable arc in both AC and DC applications. To resolve this problem, replace or regrind the tungsten, make sure the base metal is clean, or increase the shielding gas flow after making sure all your hoses are intact and leak-free.
5. What are the causes and solutions for excessive electrode consumption?
Using too much current on a given application is a major cause of excessive electrode consumption and is most easily solved by increasing the tungsten size, changing the type of tungsten you are using, or decreasing the amperage. Using the wrong polarity also can result in excessive tungsten consumption. During AC welding, for example, using more electrode-positive current may provide more cleaning action, but it also subjects the tungsten to more current and thus consumption. Instead, it is best to set the power source more toward electrode negative on the balance control to minimize the amount of current and time spent on the electrode. Using an incorrect or contaminated shielding gas can lead to high electrode consumption. Be sure to use pure argon, and check for leaks in the hoses, either from cracks or loose fittings.