How 3D-printed parts for bikes, boats and cars could help aerospace’s additive ambitions take off.
Aerospace’s additive ambitions take off
Europe’s aerospace industry quietly passed something of a milestone last month: an Airbus A310 became the first of the firm’s commercially operating planes to fly with a 3D-printed component.
The likely reason this moment passed without fanfare is that the part in question was a small plastic seat panel, rather than a structural component. The company’s arch-rival Boeing has been flying similar non-critical parts for years, and Airbus has long been experimenting with far more complex rapid prototyping and additive layer manufacturing (ALM).
But the decision to design and print a replacement seat-belt holder, after it emerged the manufacturer of the original was no longer in business, demonstrates how some forms of ALM have passed the threshold between experimental technology and established production technique.
Airbus, like many other aerospace manufacturers, is treating ALM as an exciting opportunity to create a new tool that won’t, despite the hype and myths surrounding it, revolutionise production and lead to 3D-printed planes but that will enable the creation of more complex components that could help save weight, energy, time and money.
Aerospace is in some ways one of the most the obvious places for ALM to gain a foothold in the manufacturing world because of the low production volumes often involved – 3D printing just takes too long to produce 100,000 components to meet a customer’s order. But the barrier is the very high safety standards that all products must meet.
To overcome this problem, Airbus’s engineers have undertaken several projects – with bikes, boats and Formula One cars – that allow them to experiment with ALM and develop working components of similar complexity and pressures to those that might be needed on an aircraft but with lower safety constraints.
A few years back, the company’s engineers at its Innovation Works in Filton unveiled an entirely 3D-printed bike made from nylon. But more recently, they’ve been working with manufacturer Charge Bikes to produce a titanium dropout (the part of a bike frame that connects to the rear wheel) using ALM.
‘[For commercial purposes] I don’t see the point in trying to grow a whole bike using ALM,’ says John Meyer, research team leader for ALM at Filton. ‘But I do see the point in taking the areas of most complexity and highest value and trying to make those by ALM and joining them to lower-cost products to make the bike.’
He adds: ‘If you take this further, you could envisage a truss structure for anything that needs a truss structure, including an airframe.’
A more recent project has seen Airbus and Charge Bikes use ALM to tackle an issue with even wider ramifications – how to join composites and metals without fasteners that impact the aerodynamics of a structure. Their solution was to 3D-print tiny arrow-head shaped pins that would be very difficult to produce any other way as part of the metal component that would attach a bike frame to a carbon-fibre saddle.
These are then inserted into the composite structure before it is cured, allowing it to form a bond that comprises the composite resin and is therefore much stronger than typical adhesives. And because they are 3D-printed, the pins can easily be redesigned for use with different structures.
In this sense, ALM could enable the creation of stronger, more efficient components that wouldn’t previously be possible. In a similar vein, Airbus in Germany has patented an alloy – comprised of scandium-aluminium-magnesium, “Scalmalloy” – specifically for use with 3D printers. Because it is only used in small amounts and therefore cools quickly it produces a microstructure with much higher strength and ductility than that of other similarly dense aluminium alloys and that wouldn’t be produced using conventional casting processes where the metal would take much longer to cool.
But Airbus has also shown how ALM can make existing components more efficiently, for example creating the complex connection of pipes in a hydraulic system by building them up rather than machining them out of a block of material – something the Filton engineers have been able to test with their Formula One collaborations but that could also be replicated for aerospace.
As was demonstrated with the A310 example, ALM also has great potential to enter the aerospace world through the need for spare parts, offering a potentially speedier and cheaper way to get hold of small quantities of components at short notice.
The Airbus engineers got the chance to demonstrate this when they helped their colleagues taking part in the Little America’s Cup sailing race, responding to a request for a kit of parts for a sail hinge just a week before the competition. The design capabilities of ALM enabled them to not only replicate the necessary complex geometry but also produce several different parts in a single print run, separated by removable supporting trusses.
It’s likely to be some while before we see structural components flying on commercial aircraft, given the necessary safety testing. As Meyer puts it: ‘The fact that we can do something for a one-off doesn’t mean we can do it today to an aerospace standard where you can guarantee the quality of the parts. But it shows the potential of the vision to do that sort of thing.’
The Filton team has announced its intention to 3D-print an entire aircraft wing, which due to the internal fuel and electronic systems is a much more complex structure than many people might envisage. However, by collaborating outside of the industry, Airbus have made it easier to see how this lofty goal might well be possible.