The next time you hop on a plane, there's a good chance some of its parts will have been made using a printer.
The world's top aerospace firms are increasing their use of 3D printers in order to speed up the manufacturing process, save money and make aircraft that burn less fuel.
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"The technology allows us to manufacture parts of a complexity that was just not achievable by means of standard cutting," Grazia Vittadini, Airbus' chief technology officer, told CNN.
The first Airbus plane to use a part made with a 3D printer took off in 2014. The component was a small titanium bracket, part of the pylon used to hold the aircraft's heavy engine in place.
Now the technology is a vital tool for aircraft manufacturers that are racing to meet skyrocketing demand for new planes.
How to print in 3D
3D printers deposit material layer by layer to create a solid object. Plastic is the most commonly used material, but printing with titanium, stainless steel, ceramics and sand is becoming more popular.
Also known as "additive manufacturing," the technology is used across industries to make prototypes, personalized items and small batches of products that would otherwise require molds or specialist machines.
For aircraft manufacturers and their suppliers, 3D printing helps reduce the need for expensive tools and casts.
"Casts and molds have to be manufactured very much in advance and they are not always modifiable," said Vittadini. "You invest a lot of time and money into tools, which then you may need to redo from scratch."
Boeing has so far used 3D printing to make 60,000 parts for its planes. That's a tiny percentage (a typical Boeing 747 has 6 million parts), but the US rival to Airbus is investing heavily in the technology.
"Additive manufacturing offers great potential to reduce the cost and weight of aircraft structures," the company said in a statement.
Boeing invested in 3D printing company Digital Alloy in August, saying the move will allow it to produce metal aerospace parts more quickly and at a higher volume.
Airbus has partnered with Materialise, a 3D printing company headquartered in Belgium.
Speeding up production
The International Air Transport Association is expecting the number of passengers to double over the next two decades to 8.2 billion in 2037.
That means a lot more planes need to be built — a challenge that 3D printing can help with.
"We have growing production rates and we have learned a lot of lessons," said Vittadini. Airbus struggled this year with engine shortages which slowed deliveries of its narrow-body A320neo.
Airbus had an order backlog of 7,337 aircraft at the end of November, or nine years worth of production at current rates. Boeing's commercial aircraft backlog was 5,849 at the end of September.
The use of lighter materials made possible by 3D printing should also help the environment.
"Every 15 years, the worldwide fleet doubles — that is a fantastic business case," Vittadini said. "The problem: twice as many emissions, twice as much noise, twice as much carbon fuel consumption ... this is just not sustainable."
The case for reduced emissions is simple: Lighter aircraft burn less fuel.
"We can go up to 55% weight saving, thanks to the fact that we can really just put material where we need it," said Vittadini.
Is it safe?
Some experts worry that hackers could sabotage 3D printers and intentionally insert flaws that weaken parts.
A group of academic researchers demonstrated the danger in a 2016 experiment in which they crashed a drone by hacking a 3D printer and introducing a flaw into its propeller.
Both Boeing and Airbus say they will only use 3D printers in ways that have been certified as safe by regulators.