COLORADO SPRINGS, Colo.--A key Air Force officer is optimistic about the potential capabilities derived from creating satellites via additive manufacturing, better known as three-dimensional (3D) printing.
“If the right engineering, analysis and testing (are) done…I am a very big fan of additive manufacturing,” Assistant Secretary of the Air Force for Acquisition Lt. Gen. Ellen Pawlikowski told Defense Daily Friday here at the National Space Symposium (NSS). “We just have to make sure that we do the good homework...in validating that we can get the material performance.”
Three-dimensional printing, or additive manufacturing, is the process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing technologies.
Defense contractor and satellite developer Lockheed Martin [LMT] on April 13 unveiled to reporters an ambitious plan to eventually produce a majority of a satellite using additive manufacturing. Dennis Little, Lockheed Martin vice president of production for space systems, said Friday via a spokesman the company believes it can complete the manufacturing cycle in 18 months, which he called a significant reduction to current build times upward of three to four years.
Lockheed Martin spokesman Mark Lewis said Monday the company is targeting building a satellite bus, structural elements and other technology that is currently 3D printable, and build them in a factory within 18 months. Lewis said Lockheed Martin, in about four years, will have a flight-ready satellite that has a satellite bus and structural elements made via additive manufacturing. Little said the company is currently focusing on printing the satellite bus and other structural elements at this time because there are payload components, like lenses and other electronics, that can’t be 3D printed with current technology.
Pawlikowski said the Air Force Research Laboratory (AFRL) is currently studying how to best validate that 3D printing parts and materials will have the strength and endurance to survive in demanding atmospheres like space. Pawlikowski said many materials, including titanium, have been demonstrated to have the necessary strength and endurance, but aluminum has been a little harder to prove.
Jonathan Miller, an AFRL materials engineer, said Monday via a spokesman aluminum is more difficult to prove because the processes are much different, and more difficult, than other aerospace materials like titanium, nickel and some steel. Miller said this is because low absorptivity requires much larger power sources to get the same amount of energy into the material.
High thermal conductivity, Miller said, dissipates the heat away quickly, thus requiring even more power and having to manage relatively large molten pools, which can give rise to relatively large defects during processing. Lastly, Miller said, high evaporation rates cause material loss from the part and eventual condensation onto the walls of the processing chamber.
Miller said aerospace aluminum alloys are also challenging because they have very specific microstructures that are difficult to achieve with additive manufacturing due to the fast cooling rates of the process.
Pawlikowski said 3D printing could revolutionize not just satellites but an entire industry.
“Not just because of the better efficiency and not so much waste from scrap, but the predictability (and) the qualitative assurance you can get,” Pawlikowski said.
Little said Lockheed Martin is acquiring the right equipment and developing new processes to make large-scale, flight-ready parts a reality. The company, he said, is verifying its approach by developing titanium propellant tanks and using robotic clusters to manufacture bus prototypes. Little said Lockheed Martin is still deciding which satellite program would be the best candidate for a 3D printed structure.
Lockheed Martin, Little said, is encouraged by testing. He said the company’s 3D printed propulsion tank withstood nearly double the required pressure. Little said Lockheed Martin, thinking ahead, is investing in material science research to invent new material blends for each use. Using “materials by design,” Little said the company can produce complex geometries that improve a structure’s integrity.
“We expect other components will exhibit the strength we need, considering that with 3D printing, we can now produce complex geometries that improve the integrity of the structure,” Little said.