Carbon fibre composite materials, used in everything from tennis rackets to entire jet airliners, have an impressive strength to weight ratio and are becoming increasingly popular. Carbon fibre is seen as one of the engineering materials of the future, with use expected to increase by 37 per cent over the next four years.
The benefits of the material are huge. The Boeing Dreamliner, claimed to be the world’s most environmentally friendly airliner, consists of 50 per cent carbon fibre composites with only 20 per cent aluminium. This allows it to cut its carbon dioxide output by a fifth compared with its competitors while allowing higher cabin humidity, which improves passenger comfort and reduces the effects of jet lag.
Although carbon fibre is already a success in its present form, attempts are being made to improve manufacturing both the material and parts made from it, to increase its range of applications.
Festo produces electric handling solutions for carbon fibre production and has been carrying out pioneering work with the Textile Composites Group at Manchester University’s School of Materials. The project aims to use Festo’s automation range to cut waste and improve the dimensional strength in carbon fibre products.
Traditionally, the composites are constructed by laying individual, uni-directional or woven prepreg ply over a tool mould, before curing the item with heat in an autoclave. Alternatively, dry fabric plies can be used with a resin infusion process.
However, laying techniques are regarded as inefficient, with material wastage levels of about 40 per cent, which makes the process expensive.
Now, the university group and Festo are working to create machinery and techniques that will allow the distribution and direction of the carbon fibres to be tailored to their application, said Matt Rayment, applications engineer on Festo’s applications team. The industry already offers machinery that can use this process, known as near-net shaped technology, but systems are inflexible and expensive.
‘If there are not as many fibres going in directions that we do not need, then the material could be made lighter,’ he said. ‘If, for instance, you are trying to stop two parts being pulled apart, then all your force is coming from one direction and you need a lot of longitudinal fibres. However, at the moment, the materials are put together like a mat.’
Prasad Potluri, reader in textile composites at Manchester University, said: ‘We’re looking for new ways of laying tow in predefined patterns. For the aerospace industry, we need to develop lab-scale processes for products that can be 3m long and 2m wide, with a height of up to 500mm.
‘So we needed equipment capable of operating on a large scale and with great precision, which can also handle heavy spools of carbon fibre tow. We are also looking for fast operation, so the equipment has to be highly automated.’
The Manchester and Festo team is also designing a second machine that can make tubular carbon fibre structures such as those used by Boeing and Airbus for fuselage structures but at lower cost. ‘At the moment, making such structures is quite laborious,’ said Rayment. ‘With this we will have a spiral weaving machine that can vary the ratio of fibres in one direction as compared to another — it works a little like a circular plait.’
The machinery would be ideal for constructing carbon fibre sails. ‘You could have a lot of fibres in the corners where strength is needed and less in the middle,’ said Rayment.
Away from the research field, developments are also taking place that can improve the automation processes within existing plants. Rockwell Automation’s new PowerFlex 40P AC drive has specific functions added to make it ideal for low-cost fibre and textile applications.
The addition of an embedded Pulse Train Input provides economical and configurable speed control, while drives can also be set up to ratio speed given a single speed reference.
The company offers a range of solutions specifically for fibre and textiles manufacturing, deploying flexible manufacturing strategies so users can manufacture multiple products on a single machine and quickly respond to changing market demands, lowering cost-per-metre. They also provide an automatic ability for tracking and tracing for safety-critical products, such as airbag yarn.
Recently, the company worked with DuPont on its Kevlar line. Five times stronger than steel, Kevlar is perhaps one of the best known man-made materials of the modern age, with its many uses across a wide variety of consumer, commercial and industrial applications such as tyres, ropes, cables, hoses, aerospace, cut-resistant gloves and body armour.
During an update of DuPont’s Maydown Kevlar production plant in Derry, Northern Ireland, Rockwell replaced the existing dated PLC units with Allen-Bradley ControlLogix PLCs, using ControlNet as the communications interface for the remote I/O racks. The ControlLogix units use the newly created code, based on existing ladder diagrams, to control the third-party drives that, in turn, drive all the axes within the radial spinning process.
As well as a new control infrastructure, Rockwell also supplied new communication systems that provided multiple communication lines to different elements within the process and the plant. The global demand for Kevlar products is extremely high, meaning downtime had to be kept to an absolute minimum while exactly replacing the old automation system and also interfacing with several different existing systems, some of which were bespoke to DuPont.
Elsewhere, other products of interest to high-tech and more traditional textile producers include ABB’s newest version of its IndustrialIT cpmPlus Enterprise Connectivity (ECS), which includes enhancements for quicker integration of systems, improved performance, and simplified user interface. ECS provides a streamlined, single-point interface for vertical integration between plant and enterprise business systems for improved productivity, flexibility, quality control and reduced order-to-cash cycle.
It helps customers become more competitive by providing one standard interface that connects automation and business systems. Another new ABB product is the IndustrialIT cpmPlus Smart Client, part of its Collaborative Production Management suite.
This thin client helps process customers securely access their automation systems via an internet browser for real-time visibility into the process from any location as long as a connection to the plant exists.
The use of carbon fibre materials is expected to soar in the next four years and manufacturers are looking to improve their production. Julia Pierce reports.