Page 24 - 3D Metal Printing Spring 2016

AM in Aerospace
Challenges abound in space applica- tions, as Glover noted. Launch payloads are limited in volume and mass, and parts must be robust enough to withstand excessive mechanical loads and stiff enough to withstand vibration. In space, where pointing stability is paramount for positioning antennae, cameras and solar panels, a part cannot exhibit excessive thermo-elastic distortion. And given the vacuum of space, part material must be resistant to outgassing and sublimation. Of course, the remoteness of space demands extremely high part reliability. In Glover’s view, flexibility in design, mate- rials and processes lends additive manu- facturing to space applications.
She pointed to one example, the opti- mization of a four-part structural bracket, with 44 fasteners, slated to be aboard a Eurostar E300 telecommunications satel- lite scheduled for a 2017 launch. Airbus Defence and Space was able to redesign the bracket and produce it via powder- bed laser melting as a one-piece alu- minum part, weighing 35 percent less and with a 40-percent increase in stiffness. The process also cut at least 40 percent from manufacturing time. This meshes with the program goal to additively man- ufacture 25 percent of suitable Eurostar satellite components by 2020.
NASA: More Work Needed
“Available requirements will not miti- gate additive manufacturing part risk to a level equivalent to other processes for some time to come,” explained Chris Singer, engineering director at NASA Mar- shall Space Flight Center. A limited process history translates to unknown failure modes, and with additive manufacturing being an open-loop process, in his words it requires closure or more feedback. He also noted thermal processing, surface quality, part cleaning, quality testing and vendor quality as other concerns.
Marshall Space Flight Center has a stated goal of the certified and safe flight of addi- tively manufactured hardware, so Singer, despite listing the challenges, was optimistic of a 3D-printed future in space. The center has been investigating the use of metals
for 3D printing, build parame- ters, industry variation and more, and is leading the charge for standards and certifications leading to process certifica- tions, a material database, and configuration and control mechanisms and procedures.
Many AM Opportunities for Launch Vehicles
United Launch Alliance
(ULA), a 50-50 joint venture
of Lockheed Martin and Boe-
ing, has, through its Atlas and
Delta programs, provided expendable launch vehicles
(ELVs) for U.S. government customers. Greg Schiller, responsible for strategic plan-
ning and business develop-
ment at ULA, outlined three
main applications for additive manufacturing in ELVs: tool-
ing, fixtures and ground-sup-
port equipment; mockups
and rapid prototyping; and
flight hardware. He noted that
hundreds of nonmetallic tools
had been 3D-printed (fused- deposition modeling), bring-
ing significant cost and time
savings. The ability to print for prototyp- ing brings similar savings, from months to weeks, between a model concept and an accepted design. ULA is looking to not only add polymer machines to meet increasing demand, but also increase capacity for metal printing and refine process monitoring for such work.
Challenging but Bright Future
As mentioned, challenges abound in ramping up additive manufacturing to play a significant future role. As various speakers throughout the conference main- tained, additive manufacturing still is in the Wild West stage of development.
What standards can be applied across the field of 3D printing to ensure that material properties meet application requirements? What systems can deliver, on time, and of sufficient quality, to
22 | 3D METAL PRINTING • SPRING 2016
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This image depicts the NASA Space Launch System, under development and expected to provide the heavy lifting for proposed asteroid and Mars missions. NASA has been investigating the use of metals for 3D printing, build parameters, industry variation and more, and is leading the charge for standards and certifications leading to process certifications, a material database, and configuration and control mechanisms and procedures. Photo courtesy of NASA
meet rigorous safety and performance requirements? What testing methods and protocols can be employed and standardized to reliably assess the qual- ity of safety- and performance-critical parts that now, courtesy of 3D metal printing, can be made in shapes former- ly thought impossible?
As one conference speaker noted, lead time is no longer an issue due to the length of manufacturing time. The bottleneck today is in the quality check and final sign-off. Such issues, though significant, aren’t insurmountable. As with the adop- tion of any new technology, pitfalls exist everywhere, but as metal 3D printing matures, look for it to become a staple of aerospace manufacturing. 3DMP
The Additive/Aerospace Summit returns to Los Angeles this October. For details, visit www.infocastinc.com/events/add-aero.
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