Visitors to last month’s Paris Air Show were treated to an unusual addition to the aeronautical delights on display at the stand of EADS/Airbus: a bike. But this was no ordinary bicycle. The Airbike, made of nylon, was “grown” bit by bit, or created through what is known as the additive layer manufacturing (ALM) process. This allowed complete sections to be built in one component – so, for example, the wheels, bearings and axles were made in a single piece.
Suspended next to a small 3D printing machine in Paris, the Airbike wowed visitors to the show – including French President Nicolas Sarkozy – and served to illustrate the power of ALM, a technology that some believe has the potential to revolutionise manufacturing.
So what has got people so excited about additive manufacturing processes as opposed to traditional “subtractive” methods such as machining? And why are companies such as EADS keen to demonstrate their capabilities in the area? John Meyer, ALM research team leader at the company, was in Paris and says it’s important to be able to demonstrate what the technology is capable of. “Our ambition would be to get the ALM parts onto Airbus aircraft within three years by working with our partners such as GKN.
“I’m not saying millions of parts will be on every aircraft in that timescale – but we are aiming to have made the first attempts at adoption and have some parts in production. It should grow from there.”
There’s a buzz in the air at one of EADS’s research partners, the University of Exeter – its engineers have been working with additive manufacturing machines for 10 years. A £2.6 million centre dedicated to ALM is due to open officially later this year.
The centre is benefiting from investment in some of the latest technologies, including an ALM machine said to be the only one in the country capable of manufacturing components from high-performance thermoplastics.
Dr Sara Flint, the centre’s commercial manager, acknowledges that there’s “been a lot of PR” recently about additive manufacturing. The technique has actually been around longer than that – since the late 1980s – but was mainly described as rapid prototyping. It’s the move towards making production parts through ALM that is getting people excited. Exeter has been offering prototyping services and researching new ALM materials for a number of years, Flint points out. But an injection of cash from Europe is allowing the new centre to be established, perhaps reflecting the seriousness with which the technology is now being taken.
High Wycombe-based CRDM has provided rapid prototyping services since the mid-1990s. For Graham Bennett, the company’s technical director, the term “rapid prototyping” is now synonymous with ALM. He acknowledges that there is something of a war of words going on. “What we now call additive layer manufacturing used to be called rapid prototyping, and some are trying to lose that tag because they are thinking about production. ‘Additive layer manufacturing’ gives the sense that it’s come of age.”
The technologies of ALM machines are broadly the same as those of prototyping equipment, such as selective laser sintering and fused deposition modelling. But what has changed is the quality and range of materials available to make parts. Rapid prototyping in the early days relied on specialised materials that were difficult to process and did not produce particularly robust results. But now many types of plastic and metal can be used in ALM equipment. For example, EADS’s Meyer says: “We can process very high-strength titanium alloy, steel, and aluminium alloys, so from that point of view materials are not such a limitation – I think they are actually on a par with what you can get from other processes.”
James Bradbury of the University of Exeter says: “Additive manufacturing has been around for years but one of the limitations has been the materials. That limits the applications.” But Exeter’s new machine demonstrates the possibilities on offer – it’s for selective laser sintering of high-temperature thermoplastics, which can produce components as hard as metal. Flint points out: “They are much stronger than traditional nylon materials. They have good mechanical properties with high wear resistance, good chemical resistance – and they are also biocompatible so another new market opens up for ALM, medical.”
This high-temperature plastic would normally be used in injection-moulding machines. Bradbury says: “This is an existing thermoplastic that’s used in injection moulding. Aerospace, motorsport and the medical industry are all using this material – but not this method.”
If the range of materials available has improved, ALM also opens up an exciting new world for design engineers. This includes the opportunity to optimise designs without the constraints of traditional subtractive manufacturing technology, building many components as one part.
Aerospace engineers might be able to design lighter components as a result of the technology. The complex geometries that can be easily built are another advantage as is the ability to produce new iterations of designs without changing tooling. Showing off a metal chain that has been built as one piece, Bennett of CRDM says: “ALM gives you incredible design flexibility. If a design has to be changed, it can be changed from one build to the next. You don’t have to worry about modifying the expensive, capital-intensive injection-mould tool.”
He adds: “The price of the part is entirely independent of its complexity. Because the machine just builds layer by layer, it doesn’t care what the geometry looks like – in fact a piece that is hollow is a lot cheaper to make than if it were solid, simply because it uses less material.”
EADS estimates that ALM typically produces 5% swarf compared to 90% with some traditional manufacturing. So the technology certainly has potential to cut down on waste. Further, it could simplify the supply chain because the raw material is powder. There is no need for, say, steel or aluminium to be made into a billet, for that to be made into a component, for the component to be transported somewhere else – to be made part of a bigger structure. The raw material is stored where it will be used and the structure is created. EADS describes this approach as “green, clean and lean”.
So should makers of injection-moulding machines, milling stations and tooling be worried about this burgeoning technology with a wow factor? CRDM is busy but in general its ALM machines are making low-volume parts in high value-added applications in sectors such as automotive. It also supplies low-volume parts for aerospace and for some specialised applications such as metrology and scientific devices.
Bennett says: “This works where producing tooling would be very expensive and capital-intensive. Manufacturing the parts on a one-off basis means the part price is higher, but there’s no capital expenditure to worry about.” Somewhat ironically, the company is also using ALM to create complex tooling for injection-moulding machines.
But Bennett says it is important to recognise the limitations of additive manufacturing. “I think when people are first exposed to ALM and get to grips with its capability there is this super enthusiasm that it’s a paradigm shift and everything’s going to be made this way. Unfortunately with the technology as it stands today there are some inherent limitations with what you can do with it,” he says. For example, a typical ALM machine processing plastics is accurate to 150µ, whereas an injection-mould tool can be 20µ or better. Another crucial limitation is speed: a 28-impression injection-mould tool can make 28 items every four seconds.
Bennett says: “With ALM you can make things in parallel. It’s possible to make the machine build things together, but it’s at least 100 times slower and can be as much as 1,000 times slower. So it doesn’t scale up well when you look at some of the manufacturing operations you might like to use it for.” Further, the technology is not capable of producing some of the finishes expected on products. Bennett says: “That means more time and cost, especially if labour is brought in to carry out finishing by hand.”
So it looks, for the time being, that ALM is occupying a small – but steadily growing – niche of manufacturing industry. It may be that the genuine revolution will be in 3D printers for the home. CRDM has an eye on the possibilities here and has signed up to be one of the distributors of Hewlett Packard’s latest small-scale 3D printer.
These machines, some believe, could be embraced by consumers in a manner similar to laser printers – or computers – with costs having dropped to around £10,000. Bennett says: “People might think this is far-fetched – why on earth would anyone want a 3D printer in their home? – but I think that is quite likely to happen over the next few years. These machines will proliferate and become more affordable and you’ll see more and more of them.” Such machines are already making inroads into the CAD seat market, with 5,000 units sold, Bennett says: “There will be a lot of machines sold to accompany CAD stations.”
Something that would constitute a paradigm shift is consumers printing products sold to them directly by designers, obviating the need for a factory, mass production, and distribution. The internet and the advent of 3D printing for consumers makes that sort of relationship possible, says Bennett.
Take, as an example, toy soldiers. Traditionally these would have been designed and licensed for manufacture before being shipped to a shop. Now you could have a designer at one end of the country who comes up with a design, sells it on the web to a consumer at the other end of Britain, who downloads it and prints it on a 3D printer.
Bennett concludes: “It means the supply chain has changed completely to one where the designer gets paid like a songwriter for every design they sell, rather than the selling power being in the hands of the manufacturer and the designer only being paid once.
“You’re cutting out a massive section of the supply chain.”