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ScraPping cArbon Reinforced ThermoplAstic.

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Obsolete aircraft composites get a new lease of life

EU-funded researchers demonstrated a recycling process that can derive composite waste from aircraft production and use it as raw material to produce new aircraft parts.

Climate Change and Environment icon Climate Change and Environment
Industrial Technologies icon Industrial Technologies

Composite materials are increasingly used in aircraft design owing to their very distinctive properties, including low weight, very high mechanical strength and ease of production. Inevitably, the amount of composite waste is also growing, and, therefore, researchers are working on methods for repurposing end-of-life composite parts. Thermoplastic materials are highly recyclable as they can easily be reheated and remoulded for new purposes. "Current recycling methods aiming to extend the end-of-life composite parts can recover around 80 % of the thermoplastic fibre and retain the mechanical properties of the recycled carbon fibre,” notes Pablo Ferrer Pérez, coordinator of the EU-funded SPARTA project.

Turning worthless scrap material into valuable raw materials

SPARTA project introduced a novel, eco-efficient method of scrap recycling aiming to improve the current management of thermoplastic structures reinforced with carbon fibre at the end of the product life. The process aids in considerably reducing the environmental impact of all operations related to aviation systems: virgin material production, composite manufacturing and recycling. Typically, the recycled parts stemming from aeronautic or other transport devices are large and thick (exceeding 4 mm). Conventional technologies such as compression moulding are limited in their ability to treat and reuse the complex resulting scrap material. “Our new composite cutting concept replaces the rotary movement between the cutting tool and the workpiece with a linear one to obtain chips of uniform thickness. The main advantage of the SPARTA technology is its ability to process laminates in any direction to obtain thin tapes containing long fibres,” states Ferrer Pérez. The ultimate goal is to get flat scraps so that they can be easily moulded. “Our thermoplastic composite cutting tool can generate chips measuring 50x6x0.15 mm3 and produce chopped tapes up to 32 kg/h, consuming less than 4.6 kWh/kg,” adds Ferrer Pérez.

Recycling raw materials for profit

“Accurate calibration patterns and methods are crucial for obtaining precise measurements of the unidirectional chopped tape positions. These should also help avoid high labour costs, high equipment investment and lay-up defectology,” remarks Ferrer Pérez. The SPARTA solution tackles these challenges by leveraging a collaborative robot automating the lay-up process and material consolidation. A tailor-made head deposition with a gripper places each tape in the compression moulding equipment according to the CAD pattern to obtain a consolidated panel. Ultimately, a fully aligned recycled panel made of long and continuous fibre unidirectional tapes is produced. “The automation advantage allows us to reduce the labour cost and manual defects. The estimated cost per kg of the scrap material is EUR 0.37 a truly cost-competitive alternative to virgin carbon fibres that exceed EUR 30 per kg,” notes Ferrer Pérez.

A step closer to the manufacture of sustainable aircraft

To ensure that the mechanical properties of the recycled material are comparable with those of commercial composites prepared with unrecycled carbon fibres, researchers streamlined certain design concepts, such as the fibre volume, size, weight and distribution. “The use of scrap allows us to reduce the time to market of new aviation products as it eliminates dependence on raw material availability and storage, and price fluctuations. Compression moulding also has a very fast processing time. Addressing concerns regarding the environmental impact not only during aircraft operation but also of composite material production, SPARTA’s environmental impact aligns with the European Union’s initiatives and ambitions towards a circular economy,” concludes Ferrer Pérez.

Keywords

SPARTA, composite, scrap, thermoplastic, carbon fibre, compression moulding, circular economy

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