THE LONG ROAD TO FLYING AM COMPONENTS
Text and Photos: Thomas Masuch — 2019/09/09
Additive manufacturing plays an important role at Airbus, Europe’s biggest producer of aircraft. When it comes to metal components that are relevant to aircraft safety, however, there are significant challenges to overcome in development, qualification, and production.
The aviation industry is another area in which additive manufacturing will be key going forward. By making aircraft lighter, for example, it reduces fuel consumption, which ultimately benefits both the environment and airlines’ balance sheets. »The more improvements are made to a given airplane, the more additive technology is used in the process,« explains Jens Telgkamp, who worked as an airframe research and technology manager at Airbus’s production site in Hamburg (Finkenwerder) until the end of July 2019. He is now a professor in the Faculty of Engineering and Computer Science at the Hamburg University of Applied Sciences.
Numerous 3D-printed components are already being used in updates of existing aircraft (Airbus’s »neo« models), for instance. Although Airbus has not announced any new model series at the moment, it continues to conduct a great deal of research in the field of AM. Much of it relates to the huge amount of lead time required when 3D-printing aircraft components out of metal: Such components have to be identified, designed anew, and optimized for AM processes. A corresponding process chain also has to be established, which entails significant preparations for qualification and close collaboration with suppliers.
Before the next all-new Airbus model takes off in Finkenwerder, »plenty of water will flow down the Elbe«, as they say in Hamburg. Transitions between models take longer in the aviation industry than in the automotive sector, for example, where a new generation rolls off the production line every six or seven years.
While Airbus is already making use of AM in many ways, most of them involve plastic. Telgkamp estimates that some 50,000 to 100,000 plastic components have been built into the company’s planes thus far. Instead of being relevant to safety, however, they see use in areas like cabin furnishings. Fabian Kandels, an AM specialist in production engineering in Finkenwerder, adds that 3D-printed components have also proven useful as auxiliary materials in manufacturing and assembly.
»Airbus’s qualification procedure covers the entire process description, including post-processing«
The number of metal components in use is much smaller – somewhere in the hundreds, as Telgkamp reveals. Metal parts are much more likely to be key to safety, and the manufacturing technology involved is also »simply a lot more complex«. Some examples of 3D-printed metal components that are already in the air include the double-walled fuel pipes in the A400M military transport plane and the nose landing gear mounts on the Airbus A350 XWB.
»process chain that’s much too long«
The fact that so few metal components have been built into aircraft despite AM already having been a topic in aviation for many years has a lot to do with the industry’s high safety requirements. Telgkamp also thinks that a major challenge lies in a »process chain that’s much too long due to all the testing and verification loops involved«. He says the entire manufacturing process – including post-processing (HIP) and quality control (CT) – not only takes considerable time; it also requires very large investments from suppliers. »The whole process needs to be shorter, but to make that possible, we need to know more than we do at present,« Telgkamp admits.
To continue the learning process, Airbus is exploring a series of AM technologies. In its effort to reach series production, the company has adopted most of the Technical Readiness Levels (TRLs) developed by NASA, as well. Research and development, which starts with the identification of components, accounts for TRLs 1 to 6. In the subsequent phase, the march toward series production (TRL 9) begins with the help of corresponding suppliers.
Meanwhile, the Finkenwerder site features the Additive Manufacturing Speed Shop Hamburg, which is where Airbus is conducting R&D on applications of fused layer manufacturing (FLM). The facility is also capable of producing urgently needed individual components that are already seeing use in aircraft. At its reference manufacturing shop in Filton (southern England), Airbus is researching the production of metal aircraft components using powder bed techniques. Kandels is involved here, as well – this time as a project lead whose responsibilities include the qualification of titanium components. Another technology Airbus engineers are experimenting with is wire-based deposition welding, in particular at the company’s main plant in Toulouse, France. The hope is that this innovation will someday replace more expensive components, such as those forged or milled out of titanium.
Airbus follows several process steps to identify components that it eventually wants to produce using AM, as Telgkamp explains. The first step is about using AM as a means of reducing manufacturing costs, which relates to the question at the heart of it all: For which components is 3D printing a more cost-effective option than milling or injection molding, for example? In the second step, geometric shapes are modified, ideally as a way to reduce weight. In the end, the insights gained are to be transferred to the rest of the Airbus group, including its helicopter and aerospace divisions.
Since Airbus is »not a component manufacturer«, as Telgkamp puts it, suppliers like Liebherr-Aerospace and Premium Aerotec have to be involved in the development process and undergo related qualifications. »Airbus’s qualification procedure covers the entire process description, including post-processing,« Kandels points out. Among other rigorous specifi cations, test labs have to be qualified by Airbus, and suppliers are required to source their powder in accordance with the company’s guidelines. These relate to the necessary chemical composition, morphology, flow characteristics, and other aspects.
Premium Aerotec serves as an example of how complex this process can be. A huge supplier that generates around €2 billion in annual turnover, it completed its overall process qualification for 3D-printing titanium components using multi-laser systems in April 2019. As the company itself reports, this required two years of »intensive analysis to understand and master the intricacies of the laser powder bed fusion process, as well as the reciprocal effects that take place in the subsequent steps required (heat treatment and hot isostatic pressing, for example).« In total, Premium Aerotec trialed several thousand material samples in a complicated procedure involving various test programs
The way in which it selects its suppliers is an important topic for Airbus, as well as an ongoing effort – although the aircraft manufacturer does generally have a »very limited number of companies to choose from« according to Jens Telgkamp. After all, he says, the most important thing is to »produce in a pragmatic and reliable fashion. Airplanes are the safest mode of transportation because the safety requirements are non-negotiable.«
Airbus is a world-leading company in aviation, aerospace, and related services. In 2018, its some 134,000 employees generated €64 billion in revenue. Besides offering the broadest range of commercial aircraft, Airbus is the European market leader in aircraft for refueling, military transport, combat operations, and special missions, as well as one of the world’s biggest aerospace firms.