For best results, use a gas lens in place of a standard collet body. Gas lenses minimize shielding gas turbulence and increase shielding gas coverage. They also allow the welding operator to extend the tungsten electrode further out to gain greater access to complex weld joints and improve weld puddle visibility without sacrificing weld quality.
Another important component is the shielding gas nozzle. Nozzles direct the shielding gas to the weld puddle and protect it from contaminants. When access to the joint allows, select the largest nozzle possible for the application – the larger the nozzle, the better the shielding gas coverage. Choose high quality nozzles, too – ones with 95 percent alumina are ideal. Lower quality nozzles can have thinner or inconsistent wall thickness making them less durable and susceptible to cracking, especially at high temperatures.
Next, use the proper back cap – the component applies pressure to the collet in order to secure the tungsten electrode, and seals the back end of the torch to prevent shielding gas leaks and block outside air from entering. To improve joint access, consider using a short back cap or a medium one to access confined welds.
For optimum results on full-penetration welds or highly sensitive alloys, back purge – cover the backside of the weld with shielding gas to prevent contamination from under the joint. For longer welds, trailing shields (elongated components) keep shielding gas over the weld as the torch moves in the direction of travel, away from previously deposited metal, protecting it until it cools sufficiently below its oxidation temperature.
Tungsten electrodes and grinders
For the best results, use 2 percent ceriated and/or 2 percent lanthanated tungsten electrodes. Both offer excellent arc starting at low amperages and can be used in AC and DC applications to weld stainless steel, titanium and aluminum, among other materials. The 2 percent ceriated tungsten electrode can replace pure tungsten when AC welding on aluminum and also provides 30 to 40 percent more current carrying capacity. Both tungsten electrodes have a low rate of erosion and resist tip wear.
Tungsten diameter affects arc starts and arc width so select the smallest that can handle the welding amperage. Too small of a tungsten electrode won’t withstand heat from the arc, causing it to erode or even drop into the weld puddle, resulting in tungsten inclusions. See Figure 1 for recommendations.
Use the proper grinding accessories to prepare the tungsten electrodes. A fine grit-grinding wheel (Borazon or diamond) specially designated for the purpose works to prevent contamination. Using a specialized tungsten grinder, however, provides the best results, as it offers more precise grinding angles, especially if it has machined guides for given grind angles, and is usually capable of accommodating multiple tungsten electrode diameters. Some tungsten grinders offer cutting and facing features, and are available in portable designs.
Wireless remote foot controls
Cords, fixturing and tooling often restrict welding operators who weld in the aircraft maintenance industry. A wireless remote foot control allows for quick repositioning without untangling cords, saving time and reducing operator fatigue. It also eliminates expensive failures and downtime associated with damaged remote cords, and improves safety by reducing potential tripping hazards. Wireless models can typically operate up to 90 feet away from the power source. To simplify installation, some models allow the wireless receiver to plug directly into the same 14-pin connection as a standard corded remote. Advanced wireless technology also allows for uninterrupted communication and eliminates any chance for cross talk between remote controls, allowing them to be used in the same proximity.
Helmets, gloves, and more
Personal protective equipment (PPE) is essential and begins with the welding helmet. An auto-darkening helmet allows the operator to better position the torch for welding and eliminates the need to lift the hood to inspect the weld area. These helmets use an LCD that automatically darkens in the presence of the arc, which they detect through optical sensors. Welding helmets with an “X-Mode”, electromagnetically sense the arc and provide full protection when an arc is present, in the event the sensors are obscured. The “X-Mode” also eliminates interference from sunlight and out-of-position welding angles, such as those found in hidden-cavity welds. For GTA welding on small parts, welding helmets are also available with magnifiers to help improve visibility.
Back to the basics By Joe Escobar Welding is used in many aircraft applications. One of the most popular methods is gas tungsten arc welding (GTAW), also known as tungsten inert gas (TIG...