Flying into tomorrow - digital design and manufacture of composites
Peter Giddings, Chief Engineer of the iCAP Programme at the UK’s National Composites Centre, discusses the benefits of digital composites manufacturing.
Moving to digitally enhanced production, involving controlling parameters on the fly, is challenging. Change of this magnitude involves risk and, for many companies, risk equates to cost and uncertainty.
As part of the High Value Manufacturing (HVM) Catapult, the National Composites Centre (NCC) in Bristol, UK, is a testbed for composite design and production, allowing industry to validate solutions to complex engineering challenges so they have the confidence to invest and scale.
The opportunity to pioneer digital R&D was realised early in aerospace. The sector-shaping capabilities of wing and aeroengine design have sustained UK aerospace supply chains for generations, delivering £34.2bln in exports annually, but remaining competitive is critical. In 2016, the aerospace industry, the Aerospace Technology Institute and the HVM Catapult recognised that next-generation aircraft needed next-generation manufacturing. If this challenge could be met and we could reimagine how aircraft are designed and built, the UK could gain a vital competitive advantage. Paradigms would need to shift in a similar way to the changes introduced by CNC machines and computer-aided design.
There is no better way to speed up the development process than to ensure that design and manufacturing processes are developed hand-in-hand, so that all of the supply chain is working together towards the same goal – a greener future of flight.
While partners such as Airbus, Spirit Aerostructures, GKN Aerospace and Rolls-Royce have focused on radical and forward-looking product designs, the NCC has looked to develop the equally transformative manufacturing techniques the programmes need. The result is the Digital Capability Acquisition Programme (iCAP) – a £36.7mln initiative to conceive, design and create ‘beyond state-of-the-art’ composite manufacturing capabilities.
A sea of possibilities
The qualities of composites are well known. They can provide higher specific stiffness and strength – stiffness divided by density – to reduce weight and improve resistance to both chemical corrosion and mechanical fatigue. Modern digital and processing routes help us expand what is possible with composites beyond these well-trodden paths. By exploiting the design freedoms of composites, manufacturers can reduce assembly time through component integration and adjust the material’s local properties in specific areas to achieve performance improvements.
For some structures, such as the next generation of offshore wind turbines, these additional benefits are required just to withstand the loads. Other applications, such as the Airbus-led Wing of Tomorrow (WoT) programme, benefit from cost reduction in component assembly to enable performance improvement at the lower price-point demanded by smaller aircraft.
In composites, the material microstructure and composition are designed at the same time as the component. Fibre and matrix combinations within a layer, and the sequence and ratios of different layers within the laminate, provide countless permutations even before designers begin modifying component geometry. Finding the best solutions from this sea of possibilities has allowed NCC and its partners to create structures that are more readily tailored to loads than their metallic counterparts, saving material and reducing processing time. Digital technologies are at the heart of this shift.
While a close partnership with aerospace has led to iCAP, the NCC is looking to transfer the technologies to other sectors, including wind energy, the hydrogen economy and future land transport. This means every piece of equipment created for the new programme has to enable open, yet secure, communication with a range of Internet of Things (IoT) platforms and have physical flexibility to accept the widest range of products and materials.
Underpinning everything is the ability to gather, store and analyse data so teams can quickly optimise processes and be sufficiently agile to pivot between different projects by applying concurrent engineering principles – digital gives engineers unparalleled opportunities to ‘do it better’.
Two common themes run throughout the work – the requirements for digitisation and the need for major upscaling in all stages of manufacturing to meet cost and production rate targets.
The toolkit
The NCC’s Braider, for example, has a highly flexible machine architecture. The process is simple to control, but it remains hard to measure key parameters. In contrast, Automatic Fibre Placement is a complex process with hundreds of control options, but has well-known methods to measure many, though not all, key parameters.
By combining our expertise with the machine manufacturer’s teams, both technologies now have state-of-the-art sensors capturing key process data communicated directly to the NCC IT network ready for analysis. Both these machines have required bespoke add-ons so the machines can be networked, despite widely adopted standards like OPC Unified Architecture. With this digital plumbing in place, data can flow seamlessly from the process to the engineers who will extract the information and insights to push modifications back into the machine.These two examples are indicative of the benefits of digitisation to manufacturing – there is, as yet, no one-size fits all for getting the data out of the machine and into the engineering office.
The real crux of digital engineering though is the engineer’s understanding of the process so that the right questions are asked in the right way – this is what makes the data valuable. Artificial intelligence, machine learning and data analytics are powerful tools, but they will not produce the right results without the guidance of experienced and data-literate manufacturing engineers.
Industry firsts
Digital is also about collaboration. This presents new challenges for ownership and intellectual property, but it is critical to delivering results. The WoT programme shows how collaboration can result in better products. The aim was to change design and production to meet the projected demand for replacing the ageing, A320, single-aisle aircraft fleet. That posed three key challenges – ramping up production rates of composite structures by a factor of four (equating to 60 planes per month), delivering near-term fuel-saving performance gains and paving the way for new types of propulsion. Within that list, a critical step-change has been identified – each of the primary structural components of the wing-box must be manufactured in a day rather than a week.
The NCC’s response is the new Ultra High Rate Deposition Cell, an entire value chain in a single manufacturing unit. The system reduces the number of individual pieces of material required to make a wing cover, from over 100,000 to just 150. This machine is a first for the industry. It automates the entire production process, from the rolls of raw, non-crimp fabric, through to ply-cutting and onto carefully laying out delicate final pieces to complete the lay-up. The finished forms can be as big as a 20m wing for single-aisle aircraft, or sections of the largest turbine blades.
It has been a herculean task requiring the NCC team and a network of suppliers to re-think every part of the manufacturing process. For example, UK company Loop Technology has helped to create high-rate material lay-up technology that does not exist anywhere else in the world, which is flexible enough to adapt to any industry’s requirements.
The cell comprises two 7m-high bridges that move up and down a 26m track at up to 1m/s, positioning two robotic arms to within 0.2mm accuracy. Carbon or glass fibre fabric is laid out on a 20m-long table and cut into shape using an ultrasonic knife. The material can then be laid onto a shaping tool in two ways.
The fibre form tool has 270 suction cups mounted on flexible ‘splines’, each able to position and provide suction on command. It can pick up a 1.5m x 4m piece of material and carefully manipulate it into a 3D shape and then place it on a specially shaped tool. To deposit material even faster, the fibre roll head rolls-up plies of up to 5m x 20m and then lays them across the tool surface.
New software, a combination of machine vision and laser scanning, allows the machine to auto-correct its motion to account for small deviations from desired material placement. These adaptive processes are key to enabling high-rate processes at acceptable cost, reducing the need for laborious checks and corrections that can add hours or days to manufacturing schedules.
By connecting to the network, so any sensor output, drive or data stream can be read by NCC engineers, the new process can scale and mature in tandem with the developing designs it is making.
Automating wing production meant engineers had to repeatedly break down actions into their simplest components, then work out how to recombine them into one precise, seamless movement – a ballet of machines and code. In the engineering process, the design of material, machine, process and component are no longer siloed – instead, they flow into one another to optimise the outcome. It’s a new way of working, but one that has seen this deposition process go from ‘it can’t be done’ to acceptance testing in a little over two years.
As 2020 unfolds, there will be a far greater challenge for NCC – the need to find the most cost-effective ways to help the companies we work with get back on their feet quickly, while maintaining the digital momentum. Now more than ever there is real power in working together and sharing lessons, so we can build collaborative, digitally-enhanced methods to help people recover and then progress.
Elaborating on the equipment
The NCC has explored new ways of combining carbon fibres with the resin that binds them. The Large Scale Resin Infusion (LSRI) equipment, developed with Composite Integration in Cornwall, UK, scales up a process, already used in aerospace, to the capacity required to manufacture wings and enables curing in an oven to allow cost savings compared to autoclave-cure methods.
High Temperature Resin Transfer Moulding (HTRTM) enables infusion of polyimide and bismaleimide (BMI) resins that can withstand high temperatures, allowing composites to be applied in areas where traditional resins would soften or degrade.
Inspection and validation of manufacturing, during the process as well as afterwards, is critical to cost-effective production. Laser scanning and machine vision are used to inspect dry fibre preforms during manufacture across several applications and ultrasonic non-destructive testing is applied.
The Certification, Inspection and Verification Cell (CIVC), from Ultrasonic Sciences Ltd, enables non-destructive inspection of large and complex shaped composite components. That inspection maps anomalies in the component by interpreting the attenuation of ultrasound waves as they pass through the composite between emitting and receiving transducers held either side of the component. This in-built intelligence reduces setup time and enhances signal clarity by automatically adjusting the alignment between the two robots supporting the transducers as they track a programmed scan path to ensure the system creates the highest quality scan.
The NCC has also partnered with Coriolis and Electroimpact to investigate novel ways to deposit fibres at higher rates with enhanced process monitoring. The result for Coriolis was a new, more open controller to allow data to be extracted and used to inform future optimisation, together with advanced filament winding capabilities. Electroimpact has produced the first UK-made Automated Fibre Placement (AFP) and Automated Tape Laying (ATL) machine and, together with Heraeus Noblelight, has incorporated the first industrial installation of a Xenon Flashlamp heat source that uses pulsed light to replace hazardous IR-laser radiation.
Q+A - Enrique Garcia
Composites enable engineers to have far greater freedom in how they design products, and digital enables us to ensure that the designs we select take us down the right manufacturing path from day one.
Please explain what iCAP is?
iCAP is a £36.7mln investment in 10 digitally-enabled, automated, composite manufacturing machines at the NCC. If you walk around our facility, you will see that we have new manufacturing technology, what you don’t see is all of the digital capability development that goes in parallel with the new machines. With composites, you cannot focus on manufacturing alone, you must always have a good marriage of design and manufacturing. It was very clear from the beginning of the iCAP programme that we needed to develop the digital capability around each operational one we were creating.
This a very holistic approach, because this is the only possible way of getting the maximum potential from each piece of equipment within iCAP. By the time the equipment arrives at the NCC, we make sure we have knowledge across design, simulation, inspection and manufacturing, so that our customers can quickly take full advantage of the machine’s capabilities.
Why is digital important?
It is critical, because traditionally there’s so much variability in composites. To take full advantage of their benefits, you need to be able to simulate and capture data on the wide range of possible combinations of materials and design configurations. Composites enable engineers to have far greater freedom in how they design products, and digital enables us to ensure that the designs we select take us down the right manufacturing path from day one.
Digital capabilities allow us to test thousands of configurations and then map and simulate the best manufacturing process to achieve that vision. By then adding digital across the manufacturing process, we are able to collect and feedback data at every stage, greatly reducing the need for costly interventions to improve the product’s performance. We can keep the digital log of all this design and manufacturing data to inform future developments, creating an ongoing feedback loop.
What are the main differences between other manufacturing methods and the ones from iCAP?
Some of the methods are the same. For example, composites companies are already using automated fibre placement (AFP) and automated tape laying (ATL) capabilities. What we have set out to achieve is to add instrumentation to the machinery that enables us to capture data about the manufacturing process in real-time, so that we can feed this data back into our design and simulation models, accelerating improvements in the design and manufacturing process far more quickly. This ultimately improves not only product performance, but also helps customers quickly assess and test solutions that could meet their rate and cost requirements.
We have also introduced pieces of equipment to create three completely new manufacturing cells – the Ultra High Rate Deposition Cell, the Automated Preforming Cell, and the Certification, Inspection and Verification Cell.
Because we’re an R&D centre, our equipment has to be extremely flexible. One day we are working for the aerospace industry, the following week we’re doing something for the construction sector or wind energy. So, we need to make sure when we procure technology, that the pieces of equipment can meet the needs of a wide range of industries.
What will these methods offer companies that are creating new products?
Over the last 18 months, through procuring and installing the iCAP equipment, we have gained a deep understanding of what each of the manufacturing processes can do and how to combine them. So, when a customer comes with an aerospace structure in mind, we know what the advantages, disadvantages and limitations are of those new bits of manufacturing processes. This enables us to help that manufacturer reach a decision quickly on what would be the optimum way of designing and manufacturing the parts that they’re thinking about.
While they all have specific product requirements, in broad terms, many of their challenges are similar – they are looking to achieve lightweight, durable products with long-term structural integrity (stiffness and strength) that are easy to maintain. And they want to achieve this at the lowest possible cost level at optimum speed, which is what makes composites a great fit for both aerospace and, for example, for the production of pipes for the oil and gas industry.
