Practical AM applications

Additive Manufacturing for the Aerospace Industry

Following our HotKaSt project, we now present the next insight into practical applications of Additive Manufacturing: AMB2S (Additive Manufactured Blisk to Sky) – a project that explored the use of AM for the production of aerospace components.

The aerospace industry demands the highest standards of material quality, weight reduction and efficiency. Components must be able to withstand extreme conditions, while at the same time being economically and ecologically optimized. Additive Manufacturing (AM) offers new opportunities to reduce material usage, increase production efficiency and allows components to be designed purely on the basis of their functionality rather than being constrained by traditional manufacturing limitations.

What’s on the horizon: The AMB2S approach

AMB2S has developed a holistic process chain for the additive manufacturing of BLISKs (Blade Integrated Disks), with each step tailored to the specific requirements of the aerospace industry. This includes:

• Design & Modeling: Development of optimized BLISK geometries for additive manufacturing
• PBF-LB/M Production: Manufacturing the components using a near-net-shape approach
• Heat Treatment: Enhancing material properties to meet aerospace standards
• Post-Processing: Machining of critical surfaces with optimized vibration characteristics
• Quality Control & Certification: Ensuring compliance with aerospace regulations

Using this process chain, a BLISK has been successfully manufactured using laser powder bed metal fusion (PBF-LB/M), rather than the traditional method of machining from a solid block of metal.

Why is this important?

Conventional BLISK manufacturing is material intensive and time consuming. The so-called buy-to-fly ratio – the proportion of raw material that ends up in the finished part – is often less than 20%, meaning that a large proportion of the material is wasted.

AMB2S investigated and validated the integration of additive manufacturing into aerospace certification processes using a BLISK as a case study. A heat treatment process in accordance with AMS5662 was developed to achieve mechanical properties comparable to those of conventionally manufactured components. In addition, various reference bodies were integrated for alignment and quality assurance, as well as reinforcement structures for subtractive post-processing.

Special support structures are the key to optimised finishing

BLISKs are made up of delicate structures, whether they are produced conventionally or additively. In subtractive finishing, special milling strategies are used to machine individual blocks from solid material. The near-net-shape production in AM allows for material savings. However, the thin-walled geometry of turbine blades can lead to vibrations during milling, which negatively affects dimensional accuracy and surface quality.

A key solution developed in AMB2S was to integrate optimised support and reinforcement structures directly into the additive design process. These structures stabilise the part during AM and act as vibration damping elements during mechanical post-processing. This significantly improved both dimensional accuracy and surface quality.

Furthermore, the focus was on designing support structures that reduce tool loading. Research showed that tool wear and machining time were significantly influenced by the support structures used. By optimising the structural design, supports were developed that were easier to remove and machine, making the milling process more efficient. More

What does this mean for Additive Manufacturing?

The optimisation of support structures plays a crucial role in additive manufacturing as a whole. These structures not only influence process stability during manufacturing, but also have a significant impact on post-processing efficiency. The targeted design of supports for vibration damping and tool relief is a major achievement with implications beyond the AMB2S project.

Almost every additively manufactured component requires some form of post-processing, whether by milling, grinding or other subtractive methods. The methods and insights developed in this project for optimising the support structure can be applied to other AM processes, offering a way to improve production quality and economics.

At the same time, the AMB2S results show that the mechanical properties of additively manufactured BLISK are comparable to those of conventionally manufactured components. This paves the way for the long-term establishment of AM in the production of safety-critical aerospace components. In addition to an optimised process chain with an improved buy-to-fly ratio, entirely new design approaches could become feasible – approaches that were previously limited by traditional manufacturing constraints.

Consortium

• Fraunhofer-Institut für Produktionstechnologie IPT, Aachen
• RWTH Aachen Lehrstuhl Digital Additive Production DAP
• PRÄWEST PRÄZISIONSWERKSTÄTTEN Dr.-Ing. Heinz-Rudolf Jung GmbH & Co. KG, Bremen
• BCT Steuerungs- und DV Systeme GmbH, Dortmund
• Innoclamp GmbH, Aachen
• MMB Maschinen, Montage & Betriebsmitteltechnik GmbH, Velbert
• Oetzbach Edelstahl GmbH, Velbert
• TPW Prüfzentrum GmbH, Neuss

This project is funded by Bundesministerium für Wirtschaft und Klimaschutz (BMWK).