The Role of Welding in Aerospace Manufacturing

January 11, 2024 · Leave a comment · Red-D-Arc
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Welding plays a key role in ensuring the safety and airworthiness of all aircraft. A single weld failure can lead to fatal crashes, carbon monoxide poisoning, loss of control over an aircraft, and the inability to land or take off. That’s why numerous institutes and legislative bodies demand adherence to some of the most stringent welding codes and standards in the welding industry.

While codes and regulations require exceptional weld quality, there is an inexhaustible number of welding challenges when working on aircrafts. From sensitive alloy welding to the issue of tight spaces, achieving what codes demand in a productive manner is anything but easy. Add in a massive demand for aircraft manufacturing and the skilled labor shortage, and it becomes increasingly more challenging to meet the code criteria and client expectations.

Welding Applications In the Aerospace Industry

Welding is applied to every aircraft, whether commercial jet airliner or rocket. Helicopters, airplanes, unmanned drones, space vehicles, military jets, and guided missiles all require extensive welding applications with the utmost weld quality. 

Everything from the aircraft’s structural elements to engine parts, exhaust system, hydraulic and fuel lines, and fuel tanks requires the application of various welding processes. Even composite elements of an aircraft rely on welding for making and repairing molds. Aircraft and spacecraft use some of the most challenging to weld materials, including titanium, aluminum, magnesium, specialty steels, tungsten, beryllium, copper, and specialty nickel alloys. All of these materials are difficult to weld and require a specialized approach, especially considering the need to meet code criteria.

Aerospace Welding Standards

Aerospace welding codes and standards require impeccable weld quality with minimal tolerances for weld discontinuities and no tolerance for critical discontinuities. For example, AWS D17.1 Specification For Fusion Welding For Aerospace Applications requires welds (class A, B, and C) with no cracks, overlap, incomplete fusion, and incomplete penetration (groove only), and specifies strict acceptance criteria for other discontinuities like porosity, inclusions, and undercut. It’s extremely difficult to produce welds that meet AWS D17.1 requirements, but exceptional weld quality is one of the reasons why it’s safer to travel by plane than by car. 

Aerospace manufacturers usually have to meet many codes and standards and receive certificates and accreditations from various bodies to get the best jobs and provide exceptional weld quality. The most important aerospace welding codes are:

NADCAP also plays a critical role in aerospace manufacturing. The National Aerospace and Defense Contractors Accreditation Program (NADCAP) is administered by The Performance Review Institute (PRI). NADCAP is an industry-managed approach to conformity assessment that brings together technical experts to establish requirements for approval of suppliers using a standardized approach. Being an approved NADCAP welding facility is vital for access to the aerospace manufacturing market. However, passing NADCAP reviews and audits requires exceptional performance and produced quality. NADCAP doesn’t just audit the end result, but every employee at every touchpoint, including the process of X-ray radiography, liquid penetrant testing, material selection, outsourcing, documentation, operator consistency, and other hands-on and abstract elements of the production process.

You will likely need NADCAP approval, even if you aren’t running a large manufacturing facility. Any business that provides parts or services to aerospace manufacturers who are NADCAP subscribers may require NADCAP audits. 

Other prominent organizations and agencies in the aerospace industry are:

Likewise, if you are a supplier to large aerospace manufacturers like Boing, Airbus, Aston Martin, Rolls Royce, and similar brands, you may also need to meet their specific criteria. 

Welding in the aerospace industry is challenging because welds have to pass stringent testing and meet the requirements of many stakeholders. This cannot be achieved with subpar welding equipment, especially not at the scale required by the industry today. Considering the task’s difficulty, using highly specialized, feature-rich, and reliable welding equipment is critical for achieving the needed weld quality and productivity goals.

Welding Processes Used In Aerospace Manufacturing

Aerospace welding is mainly performed using the TIG, MIG, resistance, laser, and friction welding processes. These welding technologies have many differences, advantages, and disadvantages. So, choosing a suitable welding process requires meticulous research, planning, and analysis in order to achieve the most efficient production. The three primary deciding factors are the productivity goals, required weld quality, and the specifics of the welded aerospace parts. 

TIG Welding In Aerospace

The TIG welding process is critical for high accuracy and high purity welds on exotic alloys like titanium, aluminum, magnesium, and nickel alloys. Since the tungsten electrode never touches the welded part, the process is extremely clean. The welding arc melts and fuses the material, and there are no slag or electrode inclusions in the process. 

Some commonly TIG welded aircraft parts are the exhaust system, heat exchangers, manifolds, fuel and oxidizer tanks, bleed air ducts, landing gear, motor casings, and various lines of pipes. 

The TIG welding process is one of the best arc welding processes you can use to meet stringent aerospace code requirements. For example, AWS D17.1 permits only one in-process correction attempt before the weldment is submitted for acceptance inspection. It can be very challenging to meet such criteria with highly specialized alloys and complex weld geometries. However, advanced TIG welding power sources can help reduce rework, increase inspection pass rates, and amplify your productivity.

Welding thin gauge aluminum and titanium alloys poses a risk of distortion, which is one of the biggest problems when making high-precision welds on thin sheets. This is again where high-end TIG welding power sources come to the rescue. Aerospace fabricators can significantly cut rework and failure rates by using pulsed TIG from reliable power sources that output a waveform precisely as set.

The prime example of a top-of-the-line TIG system is the Miller Dynasty 400. This machine is not just a workhorse of a welder, but one of the most sophisticated TIG machines in the industry. Engineered to provide reliability, accuracy, and unparalleled adjustability, aerospace fabricators often rely on the Dynasty TIG machines. 

The Dynasty 400 supports pulsed DC and AC TIG with an extreme pulse range (up to 5000 PPS), giving you maximum heat input control to dramatically reduce distortion and weld oxidation (discoloration) on sensitive alloys. AWS D17.1 asks for the rejection of stainless steel and nickel alloy welds that are black or titanium welds in a range from violet to white. One of the reasons why this happens is excessive heat input, which causes oxide buildup and discoloration. Excessive heat input can also lead to negative metallurgical changes in the HAZ and PMZ of the weld, which is why controlling your welding heat input is critical for safe and sound welds that can pass the inspection. 

Besides heat control, Dynasty 400 lets you modify AC frequency, AC balance, individual amperage output of DCEP and DCEN when doing AC TIG, and the AC waveform type. With this many settings, you can fine-tune your welding arc to meet many critical aerospace welding needs. For example, if you weld very thin aluminum sheets, you can use the triangular AC TIG wave coupled with a high PPS pulse to minimize distortion and maximize your chance of success.

The goal is to minimize discontinuities and defects and maximize productivity. However, achieving this goal requires a different approach for various alloys, joint types, and thicknesses, which is where advanced TIG machines like the Dynasty 400 come in. Extreme adjustability ensures you can adapt your TIG arc to almost any application and achieve high productivity.

Orbital TIG Welding In Aerospace

While welders often need to perform manual TIG welding on aircraft parts, orbital TIG is critical for the aerospace industry. Orbital TIG welding is used to join critical pipes and tubes like fuel and hydraulic lines. This is an automated welding process where the orbital head travels around the pipe circumference as it fuses the two pipes together. 

An airplane can have thousands of joints in its high-pressure systems. These pipes and tubes are exposed to extreme cyclical mechanical and thermal stresses as the airplane takes off, lands, and maneuvers in the skies. When you are flying with a commercial airliner, for example, hydraulic systems work hard whenever the plane needs to bank to one side, alter its bearing, or change its altitude. The pressure in the hydraulic lines forces the fluids to move the landing gear, flaps, spoilers, pitch control, and other critical maneuvering elements. Whenever there is a loss of pressure in the system due to a weld failure or other reasons, the pilot could lose control of the plane, depending on different factors.

Since aircraft tubes and pipes are so critical for safety, their welds must be as close to perfection as possible, and orbital TIG welding is the best way to achieve this goal.

Welding pipes and tubes manually is a significant challenge due to operator fatigue, minimal clearances, and difficulty achieving code criteria. However, automated orbital welding solves all of these challenges. Operators can weld during their shifts without fatigue being a factor, as they never have to weld in difficult positions. The orbital weld heads can be quite small, and fuse tubes in the tightest clearances. Most importantly, orbital welding provides exceptional weld quality and accuracy consistently.

MIG Welding In Aerospace

The MIG welding process also plays a significant role in the aerospace industry, especially in automated welding configurations. While TIG offers maximum weld accuracy and purity, MIG is far more productive and can produce similar results when using the right equipment.

Unlike TIG, MIG uses continuous filler metal wire. As a result, operators don’t have to pause the weld to get a new wire. Likewise, MIG is far faster than TIG in manual and automated applications. So, whenever possible, MIG is used instead of TIG to improve productivity and cut costs. 

However, MIG welding is subject to the same AWS D17.1 code for aerospace applications. So, it’s critical to use advanced process welding equipment to produce quality welds and achieve high productivity.

The Lincoln Electric Power Wave S500 is an advanced multi-process welder with high-end MIG welding capabilities. It includes over 65 welding waveforms for optimized performance for various metals, thicknesses, shielding gases, and wire types. It also supports proprietary Lincoln Electric technologies like STT, Hyperfill, low fume pulse, and highly accurate pulsed MIG performance. In addition, it supports the Lincoln Electric CheckPoint Welding Production Monitoring suite, which allows cloud weld data collection and monitoring. This can help you provide necessary data for customer ISO, statistical process control, equipment effectiveness, and other vital information that demonstrates your welding productivity and process control.

Another exceptional machine for MIG welding aerospace parts is the Miller XMT 450. It’s a multi-process welder with outstanding MIG performance. Its pulsed MIG is complemented with Miller’s SharpArc technology, which gives you total control over the arc cone and bead profile. SharpArc can help you achieve code criteria when it comes to bead profile and weld size when used correctly. Likewise, its advanced pulsed MIG mode can help you reduce average heat input and prevent distortion and burn-through on thin metals. And most importantly, applying the pulsed MIG welding process can achieve weld quality similar to TIG when set correctly. This is especially the case when combining the Miller XMT 350/450 with the Miller AlumaFeed Synergic wire feeding system. Using Miller’s Profile Pulse technology, you can achieve TIG-like welds while experiencing the MIG’s productivity gain.

Robotic MIG Welding

While manual MIG provides significant productivity gain over TIG, using a cobot to MIG weld can drastically improve productivity, weld accuracy, and inspection pass rates. When applicable, welding cobots can significantly improve your bottom line and help you overcome skilled labor shortages.

Red-D-Arc BotX™ is a collaborative robot that works alongside your operators. It’s so easy to set up and use that most shops experience its benefits in just a few hours. Your operators can guide the robot’s hand manually and use a highly intuitive smartphone app to program the weld path and arc settings in just a few clicks. 

BotX can use Millers XMT 350/450 or OTC P402L/505L MIG power sources and output a highly stable arc with multiple advanced configurations to achieve reliable, high-quality welds with minimal operator involvement. As a result, you can almost completely automate repetitive part welding and have your best welding operators focused on the most exciting and demanding applications, like welding aircraft fuel lines, tanks, landing gear, structural components, and other parts where maximum expertise is required.

Weld Monitoring For Aerospace Applications

Since welding codes and standards in the aerospace industry are so stringent and client expectations are so high, fabricators often use advanced weld monitoring systems to see and record the welding process of critical welds.

Weld monitoring allows a real-time overview of the process and lets the operator pick up defects as they occur. It’s possible to see misalignment of seams, undercuts, porosity, shielding gas coverage inefficiencies, welding tip degradation, and other problems as they occur. This can help improve productivity by preventing the problem at its root instead of waiting for the inspection. This is especially important when making a large batch of parts. Finding out that there was an issue with the welding process after completing tens of parts is an unnecessary waste of resources.

Critical welds can also be recorded to provide quality assurance. Likewise, troubleshooting is much easier if you have a high-definition video of the welding arc and the joint. 

Xiris XVC-O Weld Monitoring System is used for open arc applications, like TIG, MIG, Plasma arc, and laser welding in aerospace applications. These systems use sophisticated sensor technology to provide exceptional contrast and clear the image of excessive arc brightness. As a result, you get a clear picture showing how the metal melts and fuses. 

Red-D-Arc – Your Trusted Partner For High-End Welding Equipment

Whether you are a contractor for large aerospace brands or running your shop for private aircraft repairs, Red-D-Arc is here for all your MIG and TIG fusion welding needs. Leverage technologies like robotic welding, advanced power sources, heat induction systems, and weld monitoring cameras to deliver exceptional performance and achieve high productivity. 

Contact us today, and our experts will help you choose the welding equipment rentals for your shop.

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