Aerospace manufacturers rely on aerospace welding processes such as arc welding to efficiently assemble large, intricate end products. Because of the complexity of aerospace design, major challenges including low unit production, high unit costs, high safety standards, and severe operating conditions consistently drive new welding technology and innovations in the field.
Manufacturers in the aerospace welding industry must follow strict quality standards to ensure strong, safe, and reliable parts for all their aircraft components. Stringent regulations set by the National Aerospace and Defense Contractors Accreditation Program (NADCAP) govern aerospace welding.
To comply with these regulations while delivering the most efficient products possible, aerospace manufacturers have adopted four main manufacturing techniques in their facilities:
- Laser beam welding
- Laser-arc hybrid welding
- Friction stir welding
- Electron beam welding
Trends in Aerospace Welding Processes
In recent years, magnesium alloys have seen massive growth as a durable replacement for aluminum in aerospace products. This recent explosion in the use of magnesium results from several developments in the arc welding field to improve process efficiency.
More recent research indicates that solid-state friction stir welding and high-energy density lasers are the most promising joining techniques for magnesium alloys. These techniques reduce and, in some cases, eliminate defects that occur during conventional arc welding processes and are discovered during weld inspections.
Arc Welding
Conventional arc welding operates by forming an electric arc between the workpiece and a consumable wire electrode, heating two metal elements to their melting points so they can fuse together. This process creates strong, solid joints once the metal cools.
Arc welding has many different forms, including metal inert gas (MIG) welding, which uses a consumable electrode, and tungsten inert gas (TIG) welding, which uses a nonconsumable electrode together with a filler metal to join different alloys. Both techniques use various shielding gasses to prevent contamination.
Similar to TIG welding, plasma arc welding techniques such as variable polarity plasma arc welding construct airframe structures and fabricate external space shuttle tanks. This technology is also known as friction technology, further discussed below.
Laser Beam Welding
Also known as keyhole or deep-penetration welding, laser beam welding (LBW) requires relatively low heat input. This makes it ideal for welding components that require minimal thermal distortion.
Aerospace manufacturers typically use LBW to weld aircraft fuselage panels as it works with a number of different materials including steel, aluminum, and nickel alloys. LBW also boasts high weld quality, low weld distortion, and high volume production.
LBW produces a concentrated heat source that allows for more efficient welding processes and safe production even in open environments. Because it reduces corrosion and is lighter, cheaper, and considerably stronger than traditional rivets, LBW is particularly beneficial for Airbus A318 and A380 design.
Laser Arc Hybrid Welding
Laser Arc Hybrid Welding (LAHW) incorporates arc welding and LBW, resulting in faster welding speed and penetration depths to improve weld stability.
MIG, TIG, and plasma arc welding are the three main types of LAHW. In particular, NASA values MIG welding for its ability to perform well in both high- and low-pressure environments.
Friction Technologies
Friction welding offers a melt-free alternative to traditional welding techniques. This solid-state process heat treats engineered materials to produce high-strength end products; because it expends less heat energy, it requires less preparation to join pieces. These benefits also make it a safer welding technique than other methods.
Because friction stir welding (FSW) efficiently joins dissimilar materials, it is an optimal way to weld high-strength steel to light-weight aluminum. FSW can also be used with thermoplastics, adding to its versatility as a welding process, and is the preferred welding technique for the construction of space shuttles.
Boeing has invested more than $15 million in FSW. High-end business jets such as the Eclipse 500 saved up to $7,000 per lb. after incorporating FSW, whose ability to work with lighter material also increased their range by 4%. FSW also manufactures A380 planes, making them stronger and faster while experiencing less corrosion and wear and tear.
Electron Beam Technologies
Recent improvements to the electron beam welding (EBW) process, which operates using a concentrated heat source, have increased its popularity for the large-scale fabrication of steel structures. However, the process must be conducted in a vacuum.
Aerospace manufacturers primarily use EBW to weld low-alloy grade F22 steel and titanium.
Welding Specialization to Increase Efficiency
New advances in aerospace welding techniques have significantly expedited the manufacturing process and moved beyond the capabilities of basic welding methods, creating increasingly specialized manufacturing sectors to enable more efficient mass production.
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