Aluminum has a long, successful history in the aircraft manufacturing industry. Back in the 19th century, it was first used by Ferdinand von Zeppelin, a German general, to make the frames of his rigid airships. It demonstrated aluminum’s strength, lightweight, and high corrosion resistance. It has become one of the most used metals in the aerospace industry, especially in the aviation welding process.
The aerospace industry has become increasingly demanding in material requirements over the years. The increased aircraft size and the introduction of long-haul international flights meant major improvements in the materials being used. It required the shell and engine parts of an aircraft to be highly durable and resistant to fatigue, so different aluminum alloys have been developed for this purpose.
Aluminum has certain properties, which make it an ideal metal for use in the aircraft manufacturing process. However, despite its unique nature, aluminum has its own set of challenges. You have to select certain techniques for its welding and the right filler material, storage space, and thorough cleaning of the base material.
Read this blog to find out more about the challenges of aluminum welding and aluminum alloys commonly used in aircraft part manufacturing, and the various welding techniques for a good quality weld.
Challenges Of Aluminum Welding
Low Melting Point
Aluminum has a low melting point of 660.3 degrees Celsius which means that it has a higher likelihood of warping, cracking, and breaking during the welding process. This can pose a significant threat to the stability of the aircrafts components.
Oxide Layer
As mentioned earlier, aluminum’s melting point is very low, especially when compared to steel that has a melting point of 1370 degrees celsius. This is because aluminum has an oxide layer on it that makes its melting point much higher. It acts as insulation making it difficult to weld the aluminum properly, resulting in holes in the lower layers of aluminum. Only expert aviation welders can ensure this does not happen.
Porosity
Although hydrogen is absorbed by aluminum very quickly, it gets separated when aluminum solidifies, leaving bubbles on its surface. These bubbles, as a result, might give the final product a porous appearance that can weaken the aluminum.
Discoloration
During aluminum welding, magnesium oxides can collect at the weld on its base, leading to discoloration. Using the wrong filler metal and incorrect handling by the welder can add to this issue, such as more buildup of magnesium oxides and major discoloration.
Impurities
Improper storage and long arcs without proper protection can cause aluminum to become contaminated. As a result, the aluminum’s strength, ductility, and some of its welding properties are affected. Additionally, hydrogen can make its welding weak and hinder its performance. Therefore, you must ensure proper care and storage for successful aluminum welding.
Thickness
The varying thickness levels of aluminum can make it quite challenging for welders to ensure a good quality weld. Therefore, welders must have enough welding experience to avoid damaging the inner material.
Some other challenges of aluminum include its thermal conductivity, chemical composition, and feedability.
Alloy Series Used In Aircrafts
Each type is classified by a four-digit number according to the 1xxx to 7xxx classification system.
1xxx: Purest alloy with 99% aluminum
2xxx: Made from copper with aluminum cladding, used for aircraft fabrication.
3xxx: Good for new welders using aluminum with 1.5% manganese.
4xxx: Contains silicon, lower melting point.
5xxx: Corrosion-resistant series.
6xxx: Contains magnesium and silicon.
7xxx: Contains magnesium and zinc.
7075 aluminum alloy is most commonly used in aircraft manufacturing. The main alloying material here is zinc that increases its strength, making it suitable for aircraft part production. It is mainly used for wings and fuselages due to its corrosion-resistant property.
Welding Techniques To Use
Tungsten Inert Gas or TIG, also known as Gas Tungsten Arc Welding or GTAW, is the most common welding technique used for welding aluminum. It uses a non-consumable tungsten electrode that prevents any oxidation and contamination from occurring during the process. Even though TIG or GTAW does not require a wire filler, the process is still very complex.
Another technique employed for aluminum welding is Metal Inert Gas or MIG, also known as Gas Metal Arc Welding or GMAW. Other methods used for aluminum welding include laser beams (using a narrow beam for deep, concentrated welding), resistance welding, electron beam welding, and Shielded Metal Arc Welding or SMAW.
Acorn Welding is a trusted and highly qualified aviation welding company in Edmonton. We have the latest product designs and manufacturing capabilities required for safe aircraft welding. Contact us to get the most reliable and best services related to aviation welding.
