3D printers are already capable of producing metal components and the technology is evolving rapidly and is fast becoming capable of making complex, high-performance metal parts far more efficiently than possible with conventional machining.
Need a building on the Moon? Send for the 3D printer
BERLIN // In the near future, 3D printers will be producing metal components sophisticated and rugged enough for use in rocket engines. It is even conceivable that they could make entire satellites and buildings on the Moon.
Until recently, the increasingly popular technology, described this year by the US president Barack Obama as having “the potential to revolutionise the way we make almost everything”, was only able to work with plastic.
But the process, called “additive manufacturing” because products are created from a digital model by adding successive thin layers of material, is evolving quickly and is fast becoming capable of making complex, high-performance metal parts far more efficiently than conventional machining.
“Existing manufacturing processes sometimes put a brake on the creativity of engineers because some things just couldn’t be made,” says Andreas Bohle, a senior engineer at the German Aerospace Center. “That’s where this new technology is really great. You can pass what you’ve designed on the computer straight to the machine and it melts and fuses metal balls with a laser to create it, layer by layer.”
“The big advantage is that you can create complex forms that can’t be manufactured conventionally through cutting or drilling. You’d have to resort to casting for which you need a mould, and constructing moulds only makes economic sense if you have a large production series.”
With 3D printing, Mr Bohle says, production is cost-efficient from the first unit made.
The technology is being called the third industrial revolution and in a sign of growing confidence, the aerospace industry, where components are subject to enormous strains and cannot afford to fail, is starting to embrace it.
In July, Nasa announced it had finished testing a 3D-printed rocket engine injector, a key component that passes fuel from the tank into the combustion chamber. Aerojet Rocketdyne, a US company, designed and produced the injector.
“Nasa recognises that on Earth and potentially in space, additive manufacturing can be game-changing for new mission opportunities, significantly reducing production time and cost by ‘printing’ tools, engine parts or even entire spacecraft,” says Michael Gazarik, the associate administrator for space technology at Nasa in Washington.
Manufactured conventionally, the injector would take more than a year to make, but with the new processes it can be produced in less than four months, with a 70 per cent reduction in cost, says Nasa.
“Hot fire testing the injector as part of a rocket engine is a significant accomplishment in maturing additive manufacturing for use in rocket engines,” says Carol Tolbert, the manager of the Manufacturing Innovation Project at the Nasa Glenn Research Center. “These successful tests let us know that we are ready to move on to demonstrate the feasibility of developing full-size, additively manufactured parts.”
America’s General Electric is already using the technique to make fuel injectors for one of its aircraft engines. And China this year presented large, load-bearing aircraft components made of metal using 3D technology.
The Europeans are also embracing the 3D technology. Last month, the European Space Agency (ESA) pledged to “take 3D printing into the metal age” by building parts for jets, spacecraft and nuclear fusion projects.
At an event at the Science Museum in London, ESA showcased complex printed parts made of metal that can withstand temperatures at 1,000°C – fit for space and the most demanding applications on Earth.
“Little to no material is wasted and cutting the number of steps in a manufacturing chain offers enormous cost benefits,” says ESA. “Additive manufacturing is green technology at its best.”
The space agency aims to achieve zero waste production, saying “a kilogram of titanium would go into a kilogram of the end product”.
Together with the European Union, ESA in January launched the Amaze project – short for additive manufacturing aiming towards zero waste and efficient production of high-tech metal products. The EU-ESA team has brought together 28 institutions, and factory sites are being set up in France, Germany, Italy, Norway and the United Kingdom.
“We want to build the best quality metal products ever made,” says David Jarvis, the head of new materials and energy research at ESA.
Amaze aims to put the first 3D metal printer on the International Space Station, allowing astronauts to produce tools and new structures on demand.
The project envisages printing whole satellites and using the technology for missions to the Moon and Mars. With no need of launching heavy payloads, manufacturing in space could save huge amounts of time and money.
Four pilot factories – each one employing different metallic 3D printing methods – are being set up in Germany, Italy, Norway and the United Kingdom. In parallel, a full industrial supply chain is being established for metallic 3D printing, incorporating feedstock alloys, printing equipment, finishing techniques, measuring technology and control software.
“It is a revolutionary process that is crying out to be standardised for industry. We want to bring it from the margins to the mainstream,” says Mr Jarvis, who wants to be able to produce large metal parts within 24 hours.
However, the technology has yet to be perfected. Technical as well as legal hurdles need to be overcome before 3D printing can truly revolutionise aerospace engineering, says Mr Bohle.
Engineers need to address the problem of porosity. Laser 3D printing can leave microscopic holes in the material. These bubbles can occur when individual grains of the metal powder are not joined perfectly in the heating process. The material needs to be closely checked for these bubbles that could affect the rigidity of the component. Rough surface finishing is a further problem.
Certification is a further obstacle. “It’s a completely new technology,“ says Mr Bohle. “Products used in the aerospace industry, in planes and rockets and satellites, go through a long certification process to make sure everything works.
“With conventional production you’ve got tried and tested industrial processes that have evolved over hundreds of years and all issues have been resolved. With the new technology you’ve got to certify the powder and all the industrial steps used in production – they’ve all got to be described and approved. These approval procedures are a lengthy process.”
It will not replace all existing forms of engineering either. With large, simple components that do not require much engineering, it will continue to be more efficient to take a large chunk of metal, for example, and cut it to size, says Mr Bohle.
He does not think it will be possible to print an entire satellite.
“You won’t have a machine where you press a button and a satellite comes out of it because there are too many other components in satellites. But you’ll be able to print satellite components, and it will be possible to print one single component where previously you had to stick together four components. That’s the strength of the technology.”