Additive manufacturing (AM) is rapidly developing into an important tool for making aircraft parts for all kinds of applications, including some safety-critical components. Lufthansa Technik is taking the technique, also called 3D printing, a step further, using AM to make special tools for aircraft maintenance.
Every aircraft, once it enters service, comes with a long list of special tools that maintainers must have on hand. Some are as simple as a unique wrench designed to loosen that hard-to-reach or specially designed nut, while others are sophisticated and precisely made devices needed for making accurate and repeatable repairs efficiently. Lufthansa Technik has found many tools that it can build in-house using AM equipment, and this saves the company money and time, especially if the one tool needed for a particular job is not available when needed.
Lufthansa Technik created its Additive Manufacturing Center in Hamburg in early 2018 to consolidate AM activities, which include making flying parts and prototyping for both developing and producing new parts, as well as crafting specialized tools.
“The AM Center serves as a collaborative hub for the experience and skills that Lufthansa Technik has gained in additive manufacturing until [the expertise] then is bundled and further expanded, to increase the maturity of the technology and to accelerate the development of new products,” according to Aenne Koester, head of the AM Center.
The consolidation of activities at the AM Center means that Lufthansa Technik can design and manufacture tools and parts, perform quality control on the products, seek necessary approvals, and put the products to work. To accomplish this, the AM Center formed three clusters: prototyping, tooling, and flying.
Prototyping creates parts or tools that are designed for mocking up and fit-checking. The AM processes employ materials such as low-temperature polymers, flame-retardant materials, and high-temperature-resistant, high-strength nickel-based or titanium alloys, depending on the application.
The tooling cluster replicates special tools needed for aircraft maintenance, using all of the above materials. An example of such a tool is a socket wrench for loosening the bearing cap on hydraulic landing gear actuators. The original tool wears out relatively quickly due to the high torque levels on the caps, and delivery time for this socket wrench is usually eight weeks, according to Lufthansa Technik. The tooling cluster can make one in a week, and the in-house manufactured socket is lighter and features stronger teeth that last longer.
Other tooling cluster examples include a dual gas-value tool, which improves on the tool’s original design. Using AM, Lufthansa Technik engineers were able to build in channels to conduct inert gas to the area being welded. The gas also cools the tool during the welding process, making for a better outcome. Inert gas channels are also built into an expander jaw, used to help maintain the shape of a combustion chamber during weld repairs.
Flying parts can be even more complex, not just in the actual manufacturing, but in the regulatory approval processes, including qualification of manufacturing processes.
In developing and expanding the use of AM, Lufthansa Technik respects the intellectual property rights of the original part or tool manufacturers. “According to this principle,” Koester told AIN, “Lufthansa Technik cooperates with other companies when necessary when it comes to the reproduction of components. In addition, Lufthansa Technik has a strong supplier and partner network for the development of new parts and tools.”
The actual savings in manufacturing costs and lead times that Lufthansa Technik realizes with its AM Center are not just directly financial. “The advantages that AM offers, such as higher design freedom of parts, faster production, or weight reduction of components can be translated into resulting savings,” she said. “On the other hand, additive manufactured parts allow savings in the downstream processes: savings in turnaround times due to tailor-made tools or savings in operation due to weight reduction within the aircraft.”
Lufthansa Technik will continue exploring ways to make the best use of the AM Center. “All the developments and work carried out in the AM Center have a strong product focus,” Koester concluded. “The goal of all activities of the center is the best possible utilization of the AM technology for Lufthansa Technik, today and in the future.”