Weight reduction through 3D printed lightweight seats

How can lighter aircraft seats contribute to enormous cost savings? Andreas Bastian, research scientist at Autodesk, a company specialising in software for digital 2D and 3D designs, addressed this question. He developed a prototype of an aircraft seat frame that could not only save airlines millions of euros in fuel costs, but also significantly reduce CO₂ emissions. This prototype was realised using modern 3D printing technologies in combination with traditional casting processes.

3D printing and investment casting: a glimpse into the future of aviation?

At Pier 9, Autodesk’s 27,000 square metre technology centre in San Francisco, Andreas Bastian and Andy Harris from the Autodesk Advanced Consulting Group worked together on a new type of seat frame for aircraft. Their aim was to reduce the weight of the seat structure without jeopardising the safety-relevant stability requirements. The seat frame was optimised digitally using Autodesk’s Netfabb software. The stable basic structure of the frame was replaced by a lattice structure, which saved both material and weight. However, this complex structure posed particular challenges in terms of manufacturability, which were ultimately mastered with the help of additive manufacturing.

Why conventional 3D printing methods were not enough

Although direct metal laser sintering (DMLS) – also known as selective laser melting (SLM) – is a popular method for manufacturing metal parts, Bastian and Harris decided against using it for several reasons:

Installation space limitations: current DMLS systems do not have the installation space required to manufacture the seat frame in one piece.
Material restrictions: Magnesium, an ideal light metal for the seat frame, cannot currently be printed using DMLS due to its reactivity.
Cost: The production and preparation of metal powders is expensive and significantly increases production costs.

Instead, they opted for a combination of 3D printing and casting to produce the seat frame. ‘Although additive manufacturing holds great promise for the future of manufacturing, it is still very new to many product developers. Casting, on the other hand, has been around for thousands of years and is incredibly well known. There are hundreds of thousands of engineers, foundries and factories that are very familiar with this process. That’s one of the reasons why I’m looking for a bridge between the two processes,’ explains Bastian.

The path to an innovative prototype

To realise their vision, the researchers worked with the renowned investment casting foundry Aristo Cast in Almont, Michigan, which has a VX1000 3D printer from voxeljet. This printer enables the production of large models from polymethyl methacrylate (PMMA), a plastic that is ideally suited to the investment casting process. In the so-called binder jetting process, the powder is bonded with a liquid binder and built up layer by layer to form the model.

Once the printing process is complete, the PMMA model is prepared for investment casting. It is repeatedly immersed in a ceramic bath so that a ceramic shell is formed. This shell later serves as a mould for the metal: after the 3D-printed plastic part has been burnt out in the oven, the empty shell can be filled with liquid metal. The advantages of this approach were obvious: components could be produced at a third of the price compared to DMLS using a certified process and in the desired alloy.

Light metals for aviation: a comparison of aluminium and magnesium

Aluminium was used for the first prototype, making the seat frame 21% lighter than the conventional design. Another prototype made of magnesium even reduced the weight by 56%, as magnesium is significantly lighter than aluminium. These weight savings offer the aviation industry great potential for reducing fuel consumption and therefore considerable cost savings.

Andreas Bastian and his colleague Rhet McNeal calculated that Airbus could save over 206 million dollars in fuel costs alone by using the new seat frames in 100 A380 aircraft with an average service life of 20 years. This would also mean a reduction of around 126,000 tonnes of CO₂ emissions, which is equivalent to the annual emissions of around 80,000 cars.

Advanced technologies are revolutionising the aerospace industry

‘The purpose of this project was never to sell seat frames,’ explains Bastian. ‘Rather, it was to show how powerful Autodesk’s advanced technologies in the field of generative design and additive manufacturing are in combination with a much more widely used manufacturing process: casting.’ The seat frame is a flagship project that impressively demonstrates that the aerospace industry can benefit from this technology in the future. However, other sectors such as the automotive industry or medical technology can also benefit from the use of modern additive manufacturing processes and casting in the future.