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Friction stir welding revolutionizes aerospace industry

What is Friction Stir Welding?

Friction Stir Welding (FSW) involves a rotating tool with a special geometry – consisting of a shaft and a shoulder – pressed into the joint line of the workpieces to be joined. The friction between the tool and the material generates heat, which plasticizes the material (it becomes soft without melting). Under high pressure and the rotation of the tool, the material is stirred along the seam line, forming a solid bond.

The Process of Friction Stir Welding:

Immersion: The tool is immersed into the weld seam.
Stirring: The rotating tool moves along the seam, stirring the plasticized material.
Cooling: The tool is removed, and the material cools down, forming a solid bond.

Reibschweißen - Source: Wikipedia

The Friction Stir Welding Tool

The tool for the friction welding process typically consists of a rotating pin or needle configuration that is inserted into the material to be joined. The geometry of the tool is crucial for the welding process, as it influences the frictional heat and the plastic deformation of the material. A typical tool for friction stir welding has a conical tip that allows for good mixing of the materials to be welded.

The materials used in friction stir welding can vary and include aluminum, steel, titanium, and magnesium alloys. Since these materials often have high strength and/or specific properties, it is essential that the welding tool is both robust and heat-resistant. Additionally, the tool's geometry must be designed to ensure a strong bond between the materials while preventing defects such as voids or cracks. By optimizing the tool design and selection, high-quality weld joints can be achieved that meet the requirements of various industries.

Friction welding enables the joining of a wide range of materials. This includes metallic materials such as aluminum, steel, copper, and titanium. Additionally, plastics like polyethylene, polypropylene, and PVC can also be joined using friction welding. The high temperatures and pressure generated during the process allow even materials that are typically not weldable to be successfully fused.

In the aerospace industry, friction stir welding is primarily used for aluminum and titanium.

Materials

Advantages of Friction Welding

Friction Stir Welding Offers Several Advantages Over Conventional Welding Methods, Especially for Materials Like Aluminum Alloys, Which Are Often Difficult to Weld:

No Melting and Less Distortion: Since the material is not melted, there is less thermal stress and distortion.
High Strength of Weld Joints: Because the material is joined in a solid state rather than being melted, the result is pore-free, homogeneous connections with high strength. This is crucial for the durability of aerospace components.
Environmentally Friendly: No shielding gases or filler materials are required, making the process more environmentally sustainable.
Broad Material Compatibility: Particularly well-suited for lightweight metals like aluminum but also applicable to copper, titanium, and magnesium.

Friction Stir Welding in the Aerospace Industry

For decades, rivet connections have been the standard for joining lightweight structures in the aerospace industry. However, they come with several disadvantages: high material consumption, additional weight, and increased costs. This is where friction stir welding (FSW) presents an innovative alternative.

Using a rotating tool, the metal sheets to be joined are plasticized and seamlessly fused without material overlap or melting. The result is high-strength, pore-free joints that surpass rivet connections in both strength and lightweight design— a crucial advantage for aerospace manufacturers.

Source: Fooke GmbH

Application Areas of Friction Stir Welding in Aerospace

Aircraft Fuselage:
Aluminum alloys, commonly used in aircraft construction, can be reliably joined using FSW. This enables the production of lightweight yet robust fuselages, improving both structural integrity and fuel efficiency.

Fuel Tanks and Wings:
FSW's dense, pore-free welding technology is ideal for pressurized components such as fuel tanks and aircraft wings. The high-strength, leak-proof joints ensure long-term durability and safety.
Satellites and Space Technology:
In the space industry, complex material combinations and stringent strength requirements are common. FSW has gained prominence in this field due to its precision and reliability, making it a preferred welding method for spacecraft structures and satellite components.

Challenges and Disadvantages of Friction Stir Welding in Aerospace

Despite its many advantages, friction welding also has some challenges that need to be addressed:

Material Limitations:
Not all materials are equally suitable for FSW, requiring specialized adjustments.
High Investment Costs:
Expensive machinery and tooling can be a barrier, especially for smaller manufacturers.
Automation Complexity:
Integrating FSW into automated production lines demands technical expertise and process optimization.

Source: FOOKE GmbH (MICADO - SPANNVORRICHTUNG)

Conclusion – A More Sustainable Future

Since friction stir welding (FSW) operates without melting, it requires less energy and helps reduce CO₂ emissions in manufacturing. This process promotes more sustainable production and supports the aerospace industry's transition to eco-friendly technologies.

By implementing FSW, aerospace companies gain new opportunities: the technology not only enables the production of stronger and lighter aircraft but also optimizes manufacturing processes both economically and environmentally - a significant advancement over traditional rivet connections.

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