Fraunhofer ILT focuses on green aerospace with Additive Manufacturing and powder development
November 13, 2024
Fraunhofer Institute for Laser Technology (ILT), Aachen, Germany, reports it is developing aluminium alloy powders suited for use in aerospace hydrogen engines. As part of the TIRIKA research initiative (Technologies and Innovations for Resource-saving, Climate-friendly Aviation) of the Federal Ministry for Economic Affairs and Climate Action, the organisation has also developed Laser Beam Powder Bed Fusion (PBF-LB) Additive Manufacturing processes for commercially available materials and validated them in cooperation with partners.
“Since targeted adjustments have been made in the [PBF-LB] process, we can now achieve a relative component density of over 99.5% and a high build-up rate of more than 100 cm³/h,” shared Luke Schüller, research associate at Fraunhofer ILT.
As well as being lightweight, the high-strength aluminium alloys are resistant to hydrogen, an element that can cause embrittlement and material fatigue at high temperatures and pressures. These properties make aluminium alloys ideal candidates for use in future emission-free hydrogen engines. Moreover, thanks to the uniform laser melting process, Fraunhofer ILT’s special powders make it possible to create complex geometric forms and functional structures that cannot be made using conventional processes such as casting or forging.
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Electronic detection sensor for 0.4 millimetre particles
During the production process, a precise sensor system detects artefacts down to a size of 0.4 mm directly in the powder bed and in the melting process. This minimises time-consuming downstream inspections and significantly increases production efficiency.
Advanced processes not only affect the quality and efficiency of production, but also their environmental impact. Fraunhofer ILT utilises life cycle assessment (LCA) to assess the environmental sustainability of Additive Manufacturing processes. This includes examining the complete life cycle of a component – from raw material acquisition to recycling.
“For us, the life cycle assessment is an indispensable tool for evaluating the environmental impact of products over their entire life cycle and identifying sustainable alternatives,” explains Dr Tim Lantzsch, head of the Laser Powder Bed Fusion department at Fraunhofer ILT. However, in order to design this comprehensive process effectively, research needs to acquire high-quality and meaningful data at an early stage of the digital value chain.
The results of the LCA analyses show that, despite the comparatively high energy consumption during the PBF-LB process, the ecological footprint of Additive Manufacturing is significantly smaller than that of conventional production methods. Additive Manufacturing is, therefore, particularly suitable for repairing components because it minimises material losses and conserves resources.
Additive Manufacturing is also the focus of the EU project ENLIGHTEN (European iNitiative for Low cost, Innovative & Green High Thrust ENgine Project), which was launched in November 2022 and is managed and coordinated by the Ariane Group. Since the start of the project, eighteen partners from eight European countries that work with bio-methane and green hydrogen, among other things. The new eco-engines are intended to power the next generation of European reusable rockets and thus strengthen Europe’s competitiveness in the global aerospace sector.
As part of the project, experts from the Additive Manufacturing and Repair LMD group are developing a process to manufacture rocket components more efficiently and precisely using laser-based Directed Energy Deposition (DED), a process referred to as Laser Metal Deposition (LMD). “The special thing is that we are using LMD to drastically improve the speed and cost-effectiveness of manufacturing new types of rocket nozzles,” stated Min-Uh Ko, group leader of Additive Manufacturing and Repair LMD at Fraunhofer ILT. “Apart from its large installation space, the design under investigation has exceptionally filigree and thin-walled cooling channels that can only be generated with great effort using conventional manufacturing routes.”
The project aims to achieve laser-based DED production of a nozzle for the next generation of rockets in the Ariane programme by October 2025, along with the construction of a true-to-scale demonstrator.
One argument against conventional manufacturing is that no single company can provide all the necessary process steps in a local production facility; the components must be transported to multiple locations. As a result, the production process becomes time-consuming and expensive.
Jochen Kittel, project manager of the ENLIGHTEN project at Fraunhofer ILT, stated, “With our process technology, which saves many individual process steps, we can not only substantially reduce costs. At the same time, we are also significantly shortening the production time of a rocket nozzle.”
A controlled process
The team Fraunhofer ILT is taking an integrated approach to the project. By its end, they plan on developing a reliable, controlled manufacturing process including quality assurance for series production. An inline system will use sensors to monitor the entire process, detect and rectify process anomalies and ensure consistently high component quality.
Min-Uh Ko shared, “Once we have successfully developed the process and the demonstrator, it will mark a breakthrough. With our results, we can enable the industry, as a supplier to the aerospace industry, to produce equally large, complex and filigree structures on their own systems via LMD in the future.”
