Boeing looks to carbon recycling for weight reduction

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Boeing is nearing the implementation of a carbonfibre recycling effort for its 787 programme, aiming to reduce waste and use scraps to develop secondary aircraft structures.

The airframer is planning to collect uncured carbonfibre scrap used in the manufacturing process to build items such as brackets, clips and cured material for interior parts and passenger seat backs.

This may reduce the weight of a widebody aircraft interior by as much as 450-900kg (990-1,980lb), said Boeing's programme manager of composite recycling, Bill Carberry, who also serves as deputy executive for the Aircraft Fleet Recycling Association.

"We're beyond concept, we're doing it," said Carberry.

Prior to curing in autoclaves, scrap carbonfibre strips accumulate, and following curing certain structures requires precision cutouts for windows, cargo and access doors - resulting in unused carbonfibre panels, in which Boeing sees significant future potential.

"For the pre-production ply lay material that's been cured, we are already able to scrap cured carbonfibre, recycle it [and] bring the fibre back into manufacturing applications. We've made proof-of-concept parts, we're now working on a strategy to make proof-of-concept assemblies," Carberry explained.

It is easier to take an assemblies-driven strategy combining an array of carbonfibre parts, rather than to swap existing parts with recycled carbonfibre ones, due to the complexity of existing engineering drawings.

"If we can get whole assemblies that are made out of recycled material then it's easier to get that incorporated in the airplane. We've cracked that nut," said Carberry of the design ability.

He added: "We don't have whole assemblies designed yet. We're working on strategies of which ones to do this fall, and I think you're going to see that soon."

In addition, by working in conjunction with a British consortium that is partnering with the UK-based University of Nottingham's affordable recycled carbonfibres project, Boeing is developing techniques to use the discarded pre-cured chopped carbonfibre strands.

Carberry said the key to full industrialisation, for uses in secondary structure, is increasing the carbonfibre density from today's 10g/m3 to 200-250g/m3.

The target for "figuring that technology out" is roughly a year away, said Carberry.

He said: "Right now fibreglass is cheap, right now fibreglass is available and when we put a technology like [recycled carbonfibre] on an airplane it's all well and good to do it with a good environmental message. You have to earn your way on to the airplane."

Boeing's vice-president for environment, health and safety, Mary Armstrong, said carbonfibre scrap could have a second life as composite tooling for interior parts.

"We hope to expand that to a much wider range of aerospace tooling," she said.

Traditional metal construction affords clear opportunities for recycling, as metal scraps are compiled, melted down and reused, however, the widespread application of carbonfibre on the 787 is viewed as holding untapped potential for reducing production cost.

"We've always recycled metals in our processes, but we're just working now on the quantification on the carbon," said Armstrong, of the potential economic benefits.

"It's a technology that's new and it is building its place. It is not at the cheapest operational level as it could be, where metal recycling is at a more mature form," said Carberry.

"We still have some technologies to develop to make carbonfibre really competitive in terms of revert content going back on the airplane," he added.

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