Carbon footprints: Inside Bristol’s National Composites Centre

A major investment in world-leading production equipment has positioned Bristol’s National Composites Centre at the forefront of composites manufacturing. Andrew Wade reports. 

Bristol's national composites centre
The centre’s new braider can automatically weave up to 288 strands of carbon fibre material into elaborate hollow 3D geometries

Located on the outskirts of Bristol, the National Composites Centre was conceived in order to help UK industry push technological boundaries, forging a path for new manufacturing techniques. It is a testbed for the latest in composites technology, a proofing ground for machinery not yet mature enough for the frontlines of industry, yet with the potential to bring about major production step-changes.

iCAP is the NCC’s most recent programme of investment. A sort of factory-laboratory hybrid, the 10,000m2 space features 10 new machines, purchased under a two-year acquisition project that came in at £36.7m. With almost every component across the new portfolio of machinery made bespoke, the price tag is no surprise.

“There is one half of one piece of the smallest bit of kit – so about 0.2 per cent of the programme value – that’s off the shelf,” Peter Giddings, chief engineer for the iCAP programme, told The Engineer. “Everything else was built bespoke for us. In all 10 cases there is at least one thing that’s new to the company, in seven of the ten, it’s new on Earth.

“These specifications have been turned right up. Everyone has been stretched really hard because if I buy a machine that does what a normal machine does, I’m going to have a really hard time doing things that people haven’t thought of.”

The new cohort of equipment includes Europe’s largest carbon fibre braider, which can automatically weave up to 288 strands of the material into elaborate hollow 3D geometries for things like aircraft propellers. A new overmoulder is demonstrating how composite components can now be produced at scale, paving the way for automakers to incorporate more of the material into new lightweight vehicles.

The jewel in iCAP’s crown, however, is a massive new dual-robot cell for automatically laying huge swathes of carbon fibre. Known as the Ultra High Rate Deposition Cell (UHRDC), the two robots – weighing 45 and 24 tonnes – measure, cut, lift and place plies of carbon fibre fabric with sub-millimetre accuracy. When operating at its full potential, the machine could reduce the number of carbon fibre pieces needed for aircraft wings from 100,000 to just 150. What currently takes Airbus a week could be done in a day.

Bristol's national composites centre
The centres’s new Ultra High Rate Deposition Cell (UHRDC) uses twin robots that fire ultrasonic waves through jets of water in order to measure the accuracy of the structures produced within the cell

But making these kinds of leaps brings a unique set of challenges. For a start, the 2.5m carbon fibre plies required for the first stage of validating the new machine simply didn’t exist. Giddings and his colleagues had to take their plans to suppliers and convince them that this was where the market was headed.

“When this succeeds later this year,” he said, “we’ll be in a position to go back and challenge the materials supply chain and say, ‘we can do 2.5m, we can go twice as quick if you can get me a 5m roll’. And that’s the level of ambition that’s gone into pretty much all (iCAP) equipment.”

Even arriving at the original specs for the machinery was tricky. Manufacturing equipment is usually purchased in order to to produce a specific component at a specific rate. You bring those requirements to market and someone builds you a machine to do the job. But the NCC’s needs are different.

“A normal industrial machine is bought for what it does,” said Giddings. “Our machines are bought for how they do it and how broadly we can use it.”

If the UHRDC proves successful for wings, it will be reprogrammed to take on a range of other jobs. This flexibility is essential to justify that initial, taxpayer-backed investment.

“I need to be able to make Airbus’s wing this year and an enormous wind turbine next year,” Giddings explained. “Then later next year I need to be able to build a bridge. So we have to be designing for a huge range of products…we have to make machines that are incredibly flexible and can do a huge number of things in an industrially representative way.

“We need to get (customers) to the line of making their components, without sacrificing the flexibility for us to be able to spin round and help the next person. So we design at a target, and also other targets that we’ve defined that come next. And that’s quite difficult to do.”

To come up with the specs for the iCAP equipment, the NCC looked at the goals of major R&D projects across the UK and beyond, working backwards to figure out the type of machinery required. For the UHRDC in particular, everything from operating temperature and volume, to height from the floor, speed and power delivery, was up for grabs.

“We dragged in a huge amount of expertise from Airbus and GKN, and we sat in a room and we argued for about two and half months,” said Giddings.

Once agreement on the parameters had been decided, the specs then went out for tender, where more tough conversations took place.

“We provided a functional description of what every part of that machine needed to achieve,” said Giddings.

“It was a very big change to how we specified. And to be honest, it’s been very difficult for the manufacturing community…it’s a bloody good job people have been on our team, because it has not been easy.”

Bristol's national composites centre
The NCC’s UHRDC could revolutionise the manufacture of composite wing parts

Since its inception more than a decade ago, the NCC has worked hand-in-hand with founding members Airbus, AgustaWestland, GKN Aerospace, Rolls-Royce and Vestas, as well as on ad-hoc projects like the composite airbrakes for Bloodhound. One of its key roles is to absorb the initial risk and investment associated with completely novel equipment, testing and validating it, then helping to refine the ultimate production needs of the OEMs. For particularly complex products, multiple rounds of iteration and refinement may be required, in close collaboration with customers.

“A great example of that is the fan blades that go in the front of (Rolls Royce’s) UltraFan,” said Giddings. “We’ve done a huge amount of the development of deposition and pinning and curing of those fan blades here in the centre.

“Now that the Rolls Royce Filton facility is open, the balance has shifted, where they’re doing much more of the final production work and they’re really scaling up.”

In 2013, the NCC became part of the High Value Manufacturing Catapult, and the centre is constantly looking for new opportunities for UK industry to benefit from its work. In March 2019, it launched NCC Connect, a business unit designed specifically to support the needs of SMEs, giving them access to specialist engineers and composites technology that could help transform their business. As well as providing a gateway for smaller companies to begin exploring how they could begin using composites, it will also potentially open up sectors where the technology has previously been overlooked.

Due to the obvious lightweighting benefits, aerospace has been leading the charge for composites for a long time, alongside high-end automotive applications and offshore wind. Lighter turbine blades made from carbon fibre in turn require less robust turbine and tower components, and the resulting savings and efficiencies can more than make up for the material’s higher cost. What’s more, new techniques like those under development at the NCC could completely transform blade production in much the same way that Airbus hopes to do with wing manufacture.

Bristol's national composites centre
Another view of Europe’s largest carbon fibre braider

Other sectors have been slower with uptake, but interest is now growing as the range of benefits of composites becomes more clear and manufacturing techniques catch up with industry demands. One currently niche area with potential for future growth is nuclear fusion, where the unique material properties of certain composites – rather than simply weight – are the driver behind its adoption.

“We’re currently looking at a composite demonstrator for UKAEA (UK Atomic Energy Authority),” said Giddings. “There are applications for some types of composites in a tokamak. Applications of ceramic matrix composites, where fibres reinforce the matrix of silicon carbide ceramic. That can stand huge temperatures and would be in the tritium blanket.”

Other sectors set to benefit include oil & gas and the wider energy industry, with composites playing a role in pipelines, pressure vessels and perhaps even the enormous towers for wind turbines. According to Giddings, there is certainly no shortage of work for him and his colleagues at the NCC, and that’s not likely to change any time soon as composites become more widely adopted outside the usual industry strongholds. “We’re really fortunate that we have these exciting challenges coming in from very cool projects,” he said.

“And that breadth is what comes next really. It’s a big part of our mission over the next three years. We’re not going to be the National Aerospace Composites Centre. We’re the National Composites Centre.”