The titanium brackets for Airbus’ telecommunications satellites are manufactured using an EOS EOSINT M 280 3D printer. (Airbus Defence and Space).
BILL READ looks at how 3D printing technology is set to revolutionise the space industry with faster development times, cheaper components and the ability to manufacture objects in orbit
Until recently, components for rockets, satellites and other space equipment have been constructed by traditional methods – in the case of metal components by cutting large billets or forgings down into the required shape – an expensive process that requires both specialist tooling and generates a large amount of waste. However, in the past few years advances in additive manufacturing (AM) technology have enabled engineers to create equivalent parts in less time at lower cost. The process of AM, also known as 3D printing, creates three dimensional products by ‘printing’ parts layer by layer from powders – such as plastics, aluminum, titanium or stainless steel - using computer-aided design (CAD) templates.
AM techniques have been utilised by designers as the ideal tool for creating prototypes for testing which can be altered and refined for little additional cost. 3D printing of both plastics and metals is now in widespread use in a variety of applications, including the automotive industry, medical, dentistry – and in aerospace. More recently, AM has begun to be used to produce parts for series production aircraft and also for space rockets and satellites.
Printed rocket motor
New Merlin rocket motor for Falcon 9 – SpaceX’s Falcon 9 rocket motor now includes 3D printed components. (SpaceX)
In January 2014, US commercial space company SpaceX launched a Falcon 9 rocket with a 3D-printed main oxidizer valve (MOV) body in one of the nine Merlin 1D engines. The valve operated successfully with high pressure liquid oxygen under cryogenic temperatures and high vibration. According to SpaceX, the printed valve body exhibited superior strength, ductility and fracture resistance compared with a traditionally cast part, with lower variability in materials properties. The MOV body was printed in less than two days compared with a timescale of several months for a casting. SpaceX is currently testing its new SuperDraco rocket engine which will be used to power the launch escape system on the Dragon 2 spacecraft capable of manned missions. The engine includes a 3D printed engine chamber made from Inconel high performance superalloy which was created in-house in just over three months.
NASA rocket motor
A 3D printed rocket injector built by NASA is tested at NASA’s Marshall Space Flight Center. (NASA)
NASA has also tested a rocket engine injector made with a 3D printer which, it claims, far outperformed its conventional counterpart. The component, which sends propellant into the engine, was designed by NASA engineers and the parts built by selective laser melting which involved layering metal powder and fusing it together with a laser. The additive process allowed the designers to create an injector with 40 individual spray elements, all printed as a single component rather than manufactured individually. Only two parts were required to create the injector, instead of 163 required by traditional manufacturing methods. The component was not designed for use in a particular rocket but was similar in size to injectors used to power small rocket engines and a similar design to those used in larger engines. Two injectors were tested – one printed by Solid Concepts in Valencia, CA, and the other by Directed Manufacturing of Austin, TX. The injectors are designed to work at very high temperatures, mixing liquid oxygen and gaseous hydrogen together which combust at over 6,000°F, producing more than 20,000 pounds of thrust.
ULA selected ULTEM 9085 for its ability to withstand a wide range of extreme temperatures. (ULA)
US rocket manufacturer ULA has begun using AM to produce parts for its new Atlas V rocket. Using two Stratasys 3D printers, ULA is producing thermoplastic versions of the environmental control system (ECS) duct used to deliver nitrogen to sensitive electronic components within the rocket booster which will launch with the new 3D component in 2016. The previous design for the ECS duct assembly contained 140 parts but ULA has been able to reduce the number of parts to only 16, speeding up installation time and lowering costs by 57%. ULA’s next plans are to increase the quantity of 3D printed parts on its next generation Vulcan rocket to over 100.
Airbus Defence and Space also uses additive manufacturing to create titanium retaining brackets used on its satellites to link the satellite body to reflectors and feeder facilities mounted at its upper end. The brackets, which are subject to high levels and stress and temperature fluctuations from –180 to +150 °C, were created by German company EOS using a laser beam melting and hardening deposited metal powder layer by layer. Production time of the three brackets required for a satellite has been reduced to under a month and each bracket is 300g lighter.
Lockheed Martin has also started using 3D printed components for its satellites, in which titanium is heated and applied in successive layers to create different shapes. The company plans to expand the process the ultimate aim of building a complete 3D printed satellite.
Manufacturing in zero gravity
There has also been much talk about the future possibilities posed by 3D printing in space. In 2013 NASA, together with the US Air Force Space Command, and Air Force Research Laboratory commissioned the National Research Council to conduct a study into the prospects for using of additive manufacturing in space. While the report concluded that there were numerous potential benefits to AM in space, such as reducing the cost of raw materials, payload sizes, and the need to launch replacement parts into orbit, it also pointed out the space environment would pose its own challenges of how to operate AM technology in zero gravity, the vacuum of space and intense thermal fluctuations. It would also require extra human resources to monitor the process and additional research into the material’s properties in space. However, the report also concluded that AM could lead to new concepts of how spacecraft and satellites could be designed and manufactured in a space environment.
Out of this world
In 2015, the first 3D component made in space was created using a 3D printer on the International Space Station. (madeinspace.us)
Practical tests have already begun on printing 3D structures in space. In September 2014, the first zero-gravity 3D printer was delivered (by SpaceX) to the International Space Station (ISS). The printer was able to fabricate the very first object made in space - a faceplate for its own extruder, with ‘Made In Space’ printed into it. The faceplate will serve as an access panel to the print head and is a functioning part.
In December NASA emailed CAD drawings for a socket wrench to be printed out on the ISS. (NASA)
In December 2014, NASA emailed CAD drawings for a socket wrench to astronauts aboard the ISS, who then printed the tool using the 3D printer. A second 3D printer is to be sent to the ISS by the European Space Agency (ESA) in June 2015. NASA has launched the ‘GrabCAD Challenge’ which invites designers to submit concepts on how to re-design a traditionally-manufactured crew tool so it can be 3D printed in space.
Print your own rocket motor
Open access rocket motor
If any readers are interested in printing a rocket engine of their own, a US engineer, Graham Sortino, has created open source plans for a 3D printed liquid-fuelled, rocket engine which have been posted on the Internet on https://github.com/gNSortino/OSREngines/tree/master/Engines/2014-GOXEthanolRegenEngine. According to Sortiono, the parts can be printed using either direct metal laser sintering (DMLS) or selective laser sintering (SLS).A longer article on the wider impact of additive manufacturing techniques on the aerospace industry, including aircraft and engine production, will appear in the June issue of AEROSPACE.