Welding in aircraft maintenance applications is rarely easy. In addition to joint complexity, there is also the matter of the specialized metal alloys that are used. Materials like stainless steel, nickel alloys, and titanium offer excellent corrosion resistance and extended service life; however, their highly reactive nature makes completing high quality welds challenging. Typically, welding procedures specify the GTAW (gas tungsten arc welding) process for the job, as it minimizes heat input to help protect against distortion or burn-through, and also offers precise control over the welding arc.
To achieve the benefits offered by these materials and to ensure the best weld quality, it is critical to have the right GTAW accessories. From the torch and tungsten to the proper personal protective equipment, the proper tools improve the success of the application, as well as the welding operator’s comfort and safety.
The GTAW torch carries the welding current and directs shielding gas to the weld. On complex joint configurations with varying angles that are commonly found in aircraft assemblies, a torch with a modular design is an excellent choice. These torches allow for customization of a single torch body into multiple configurations by adding a flexible neck and/or different head designs. Modular torch designs also help minimize downtime for torch changeover and lower costs for purchasing multiple GTAW torches for each weld station.
A water-cooled torch design is preferred for higher amperage applications or those that require welding for long periods of time – they stay cooler than air-cooled models, making them more comfortable for the welding operator. These torches are also small, light, and easier to maneuver, which is advantageous when welding small components, thin sections, or in difficult-to-reach locations. Water-cooled designs require a separate cooling system, so their use is generally limited to shop applications. When portability is a factor, welding operators can instead rely on an air-cooled torch.
Both air- and water-cooled torches are typically available with flexible necks to ease joint access and positioning.
Cables, hoses, and leads
Welding operators can choose between vinyl or rubber compound hoses and cables. Vinyl cables and hoses are less expensive and are practical for light-duty GTA welding repairs; however, they are less flexible, making it difficult to maneuver the torch when out-of-position. Braided rubber compound hoses and cables provide better heat resistance and resist kinking, which prevents shielding gas disruptions and makes them more flexible and comfortable to use. The braiding adds to the durability of torch hoses and when color-coded, helps simplify connections and changeover.
Welding operators should use the shortest cable possible to help prevent voltage drop in the welding circuit and maintain the most consistent weld parameters. A 12 1/2-foot torch package is good for welding within a weld cell, provides more consistent arc starting, and keeps excess cables from cluttering the weld area. A 25-foot torch package is good for longer welds or for applications requiring greater movement; these cables are not ideal in a weld cell, since they may coil, kink, or cause a tripping hazard.
Having a good work lead and work clamp is also important. Welding operators should check regularly that the components are in good condition. Poor work connections disrupt the welding circuit, hinder arc starts, and create unwanted arc marking of the part that can lead to scrap or rework.
Front- and back-end torch consumables
Collets and collet bodies create the electrical connection between the torch and tungsten electrode to generate the arc, and they also distribute shielding gas around the electrode to the work surface. Look for consumables that can withstand the heat of the application without failing prematurely or creating an unstable arc. Avoid lower quality consumables – they may be less expensive, but they are often less heat resistant and their shielding gas ports may not hold the tolerances necessary for good gas coverage, leading to weld defects like porosity or atmospheric contamination (oxidation).
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...