Printing flyers

The flexibility and weight-saving ability of 3D printing could one day deliver huge savings to the aerospace industry. Lou Reade reports. In the not-too-distant future, aerospace companies may abandon their existing approach to manufacturing – bringing separate components together for final assembly. Instead, planes might be made layer-by-layer, in a gigantic 3D printer – a factory-sized version of the desktop machines that currently make prototype models or ‘World of Warcraft' figures. It's not a reality yet, but EADS is already predicting that planes might be made this way by the middle of the century. That's just 37 years in the future. Look back by that amount of time, to 1976: could engineers then have imagined a plane that was more than 50% carbon fibre? 3D printing or additive layer manufacturing (ALM) as it's also known, builds parts up layer-by-layer, from either plastic or (increasingly) metal. The aerospace industry is almost perfect for it, due to the fact that production volumes are low enough – and budgets high enough – to make it a reality. The industry is already investigating the potential for these technologies, and some of the major manufacturers are jostling for position in this ‘strategic' field. GE stole a march on its competitors with its recent acquisition of Morris Technologies – which has established itself as a specialist in the production of 3D aerospace parts. The move means that other companies which had relied on Morris' expertise will now have to go elsewhere, or develop their own. Designers and suppliers are also working hard to convince the industry of the benefits of the technology. One recent UK project called SAVING, funded by the Technology Strategy Board in the UK, was set up to investigate the energy-saving potential of using 3D printing in place of conventional manufacturing techniques. “We quickly realised that ALM is actually very energy-intensive,” says Mike Ayre, managing director of design agency Crucible Industrial Design, and a member of the project. “There's no way you could call ALM processes ‘green': it takes a lot of energy to melt titanium with a laser.” Despite this, he says there is still plenty of potential for ALM as an energy-saving technology as long as it is used in the right way. “We could use ALM to save weight, which will save energy and money in the long-term,” he says. “We just have to accept that the ALM parts themselves will be expensive.” He adds that targeting high volume parts will have the greatest effect, in terms of saving fuel, carbon and money. SAVING partners – and many other researchers – have considered many ‘non critical' parts like clips, brackets, hinges and latches. “It works on the same principle as the Team GB cycling team,” he explains. “Improving lots of parts, in a small way, can have a huge effect.” The partners decided that a belt buckle would be an ideal ‘demonstrator' part to illustrate the flexibility and weight saving benefits of 3D printing. At the same time, it was easier for people to relate to than a complex engine component, although these types of parts could also be made this way one day. The buckle was designed to look similar to a conventional buckle with similar design principles but uses far less material. ALM allows non-essential portions to be simply removed – and uses laser-sintered titanium rather than steel or aluminium. “Titanium is actually easier to process this way than steel or aluminium,” says Ayre. The titanium belt buckle weighs 70g, rather than 155g for a steel one. Working on the principle that a typical Airbus contains around 850 of these buckles, the total weight saving would be 72.5kg – equivalent to 3.3m litres of fuel at a cost of £2m. Of course, the main element of the weight saving is to use titanium rather than steel or aluminium. So has 3D printing added anything extra? “We did two things that would not be possible with conventional techniques,” states Ayre. “First, we can vary the wall sections at will. That would be very difficult with casting or pressing. And secondly, the two components of the belt – which are usually assembled – can be built in-situ: that means you remove the assembly cost.” UK-based ALM bureau 3T – another member of SAVING, which collaborated with Crucible on the belt buckle – is already working with major UK aerospace companies to provide 3D printed parts. “We expect the initial applications to be for low-criticality parts like ducts, clips and brackets,” says Ian Halliday, chief executive of 3T. “After that, it might be electronics boxes.” He says safety will be crucial in the adoption of these technologies. “It all comes down to risk: if you put anything on a commercial plane, you must have a good reason for doing it,” he says. “But there are higher risk parts too, such as on compressor turbine blades: we actually build parts for turbo-chargers, for engines that run at very high speed. ALM is used to make safety-critical parts in F1 – so it could conceivably be used in aerospace too.” Another benefit of 3D printing is that parts can be combined. “You could have a bracket that's also a heat exchanger,” he says. “Multi-functional components save weight and complexity. The benefits are huge if they're applied in the right way.” 3T and Within Technologies teamed up to design a conceptual heat exchanger that can be made using ALM: the repeated structure has a very high surface area to maximise heat transfer. The component was built in one piece, without support structures, in less than one week – far quicker than a conventional part. ALM is currently a batch process, and will need to be converted to a continuous process in future if throughput is to increase. And there are many other factors to get right before the any planes start rolling out of the 3D printer. “We've got to the point where major companies are comfortable that ALM is a significant technology,” concludes Halliday. “They've identified the components that might be suitable for ALM production. But it will only be one of their production tools: it will not solve all the world's problems on lightweighting.” www.crucibleid.com www.3trpd.co.uk