CO2-optimized aviation applications
Joining forces for an improved climate footprint
The aviation industry faces an immense challenge: to improve its climate footprint, it must drastically reduce its carbon emissions. Even if the largest CO2 savings lie in sustainable aviation fuels (SAFs), more efficient drive systems and aerodynamic optimizations, the potential of selecting the right materials is often underestimated. Lightweight and sustainable raw materials play a significant role in reducing emissions and improving efficiency - making them an important element of more environmentally friendly aviation.
Aluminium is essential in this context. Thanks to its low weight and high strength, it has become the material of choice for structural and fuselage components in aircraft. Aluminium offers excellent recyclability, which makes it possible to further reduce its carbon footprint in the value chain.
High quality, safe - and sustainable? Conflicting demands in material selection
The aviation sector has strict and highly specific requirements regarding material quality. High-strength aluminium alloys with high damage tolerance are used to meet these strict safety and performance standards. These materials are characterized by strict tolerances with regard to their chemical composition. Above all, the iron and silicon content of these alloys is strictly limited to ensure their longlife fatigue strength and reliability. This is why, traditionally, lower proportions of recycled material has been used in such alloys. Instead, aviation alloys have relied on a very high proportion of primary aluminium and alloying materials - far higher than in products for other industries. However, primary aluminium production is energy-intensive: it consumes around 20 times more energy than aluminium recycling. It is, therefore, essential that we find resource-friendly ways to deploy recycled alloys without compromising on strict requirements regarding material properties, which are directly linked to product safety. The central challenge lies in resolving the conflict between the high material requirements in the aviation industry and the urgent need to increase recycling rates. So, how can we master this balancing act?
Joining forces: Creating solutions through expertise and partnerships
The answer lies in the sub-heading of this article: joining forces - which also describes AMAG’s philosophy in addressing the complex requirements related to aluminium recycling. In Ranshofen, AMAG casting and AMAG rolling have pooled their expertise to produce high-quality (aviation) alloys from aluminium scrap. AMAG is now able to recycle almost any kind of aluminium scrap by drawing on state-of-the-art sorting and smelting technology along with specialist expertise developed over decades. However, improving sustainability in the material chain calls for more than just internal expertise. Instead, close collaboration with customers is essential, as the sources of scrap have a significant influence on its quality. The majority of aluminium semi-finished products supplied to customers in the aviation industry undergo machining. This resulting recyclable waste primarily takes the form of metal chips, which are often contaminated with moisture and oil residues from the machining. These chips are rarely collected or stored separately by material. This hampers recycling because retrospective sorting and separation is not cost-effective.
Did you know?
Even with a maximized proportion of scrap material, primary aluminium and alloying elements (e.g. Zn, Cu and Mg) must be added to the melt to achieve the target composition of the alloy.
The alloy’s carbon footprint can be further reduced (subject to purity requirements) by adding primary aluminium produced through low-CO2 smelting.
The perfect closed-loop process between AMAG casting, AMAG rolling and AMAG components: Examining the case of 7475 alloy aviation plates
The closed material loop encompassing AMAG casting, AMAG rolling and AMAG components is an outstanding example of how to achieve outstanding resource efficiency. It starts with the rolling slabs, which are produced in AMAG casting’s ultra-modern plant using special smelting and casting technologies. These technologies ensure that the material properties essential for aviation products are precisely monitored.
The resulting rolling slab is then transported to one of the rolling mills on the Ranshofen site. It might be rolled, for example, into high-quality plates made from the high-performance 7475 alloy, which then undergo heat treatment, stretching and intensive quality testing. Scrap is inevitably produced during the rolling process. It is particularly important to recycle such scrap on site. Thorough scrap separation and short transport routes make it possible to recycle material and conserve resources at the casting plant, which effectively closes the material loop.
In order to guarantee maximum consistency in material properties while minimizing deviations and defects, AMAG provides 100% ultrasonic tested rolled plates to all its aviation customers (Figure 1), as well as to AMAG components. This valuable raw material is then cut into its final shape through machining with milling machines. In the process, 90-95% of the plate is turned into chips, with only 5-10% of the plate by weight ending up as the finished component. This means that, by weight, the process produces 10 to 20 times more chips than components. In addition, coolant is applied during the machining process. The more chips are produced, the more coolant is required, which complicates the subsequent recycling of these chips and also reduces yields.
Due to the different cut geometries and cutting speeds, machining produces chips of different shapes and sizes, including tiny particles with a large reactive surface area. This leads to material losses of up to 10% during smelting. In an effort to counter these losses, AMAG precisely sorts, cleans and briquettes these chips before returning them to the casting plant (Figure 2). This significantly reduces the use of primary aluminium.
The recycled material is turned back into rolling slabs, which continue their journey through the closed production cycle. Despite the extremely high requirements regarding the alloy’s damage tolerance, 7475 alloy plates can also be supplied with an AL4® ever certificate. The optimized material quality and short transport routes in the loop ensure a smooth, disruption-free supply chain. A perfect cycle.
It is vital that customers separate scrap of different alloys, or at least scrap of different alloy families (e.g. 7xxx or 2xxx). Mixing ratios must also be kept as constant as possible to avoid downcycling and facilitate the target use of recycled materials. AMAG advises its customers extensively on these issues so that, together, we can develop economically and environmentally optimized solutions.
AMAG offers its customers a closed-loop process - for which the internal value chain between AMAG casting, AMAG rolling and AMAG components serves as a prime example. In this case, AMAG collects production scrap from customers directly. If customers are unable to dry waste chips, AMAG takes care of this. AMAG can carry out the necessary sorting steps for larger pieces of scrap. The recycled material can then be turned back into high-quality wrought alloys and, ideally, used to manufacture exactly the same components. By closing the material loop, AMAG not only provides innovative recycling solutions but also creates sustainable, long-term partnerships. This is wholly in line with the aim of joining forces and setting common goals.
Customer benefits
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Full service: Sheets, plates, cut plates, finished components and recycling of chips and plate cut-offs.
- Cost efficiency: Better buy-to-fly ratios achieved with contour saws and efficient nesting.
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Reliability: Stable supply chains and reduced risks, thanks to an integrated value chain and optimized production planning.
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Sustainability: State-of-the-art recycling methods and environmentally friendly technologies contribute to a smaller carbon footprint and lower resource consumption.
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Quality: Precise and durable products that correspond to the strict standards in the aviation industry.
Optimizing aluminium cutting
Increasing production volumes combined with strict environmental regulations and limited resource availability calls for constant optimization of production processes. A key metric in this context is the buy-to-fly ratio (BFR), which describes the relationship between the weight of the raw material and the weight of the finished component. The aim is to minimize the BFR, thereby reducing metallic waste, cutting costs and improving environmental sustainability.
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Customized dimensions for maximum efficiency Optimizing plate dimensions and improved targeting of cutting processes is a promising means of increasing material efficiency. AMAG adjusts the dimensions of rolled plates in line with individual customers’ requirements to minimize material losses.
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Precision through modern technology AMAG also offers contour cutting methods that further reduce material losses, thereby improving material efficiency. However, these methods involve more complex production processes and require more precise planning. AMAG has a modern contour band saw capable of cutting aluminium plates with a high degree of precision - in straight lines and along more complex, curved contours. This ensures efficient material use while keeping production waste to a minimum.
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Intelligent nesting for optimal material utilization Neben einer ausgezeichneten Planheit wird AMAG PROCATH® auch durch einen geringen Eigenspannungsanteil charakterisiert. Dies gilt speziell für die entspannungsgeglühten Zustände H34 und H36. Beim Endkunden wird damit einem eventuellen Verzug beim Anschweißen der Tragstangen an das Kathodenblech vorgebeugt.
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Intelligentes Nesting für optimale Materialausnutzung: Another key to material efficiency during machining is “nesting”, which involves strategically arranging components on the base plate to optimize material utilization. AMAG offers different nesting strategies, which can each be tailored to customer requirements:
- Linear nesting: Components are arranged in a fixed sequence in order to simplify production planning. This is suitable in particular for large batches with little variation in the component.
- Free-form nesting: Components are nested in a way that utilizes even small areas of material. This requires complex calculations but maximizes material yields.
- Hybrid nesting: A combination of linear and free-form nesting, combining flexibility and efficiency. This strategy is particularly well suited to medium-sized component batches with varying requirements.
Close collaboration with the customer is vital in this context, as the specifications for component manufacturing are defined down to the finest detail. Other than in exceptional cases, any changes to the nesting strategy - such as changing the orientation of components to be cut from the plate - require prior consultation with the customer (Figure 6 ).
AMAG AL4® ever: A smaller carbon footprint for your product. Guaranteed.
AMAG produces high-quality sheets and plates for the aviation industry, offering maximum efficiency and sustainability in both areas with its innovative AMAG AL4® ever portfolio. The AMAG AL4® ever product line is specifically designed to reduce and guarantee the carbon footprint of AMAG aluminium solutions - without compromising on product performance. AMAG demonstrates the carbon footprint of its AL4® ever products within pre-defined guarantee levels, issuing an AMAG AL4® ever factory certificate to confirm this for every ton of aluminium produced in accordance with contractually defined annual volumes. Our customers can use these AMAG AL4® ever factory certificates to determine the Scope 3 emissions in their supply chains. This provides a well-founded and transparent basis upon which to communicate their sustainability goals.
Thanks to our long-standing expertise in recycling and successful collaboration with customers to optimize scrap quality, AMAG is able to supply aviation plates in 7075 and 7175 alloys in AL4® ever quality with a carbon footprint of less than 4 tons of CO2 per ton of aluminium. This delivers real added value for sustainable aviation products.
