July 25, 2013
3D Printed Rocket Part Tests A Success
Lee Rannals for redOrbit.com - Your Universe Online
NASA has tested 3D printed rocket parts, showing that the future is bright for the less-expensive methodology.
Engineers decided to try 3D printing rocket parts in order to help save NASA and the industry some money, as well as open up new affordable design possibilities for rockets and spacecraft. Now, NASA is saying that tests have shown these rocket engine parts are comparable to those made the old-fashioned way.
NASA engineers at the Marshall Space Flight Center built two sub scale injectors with a specialized 3D printing machine and completed 11 main stage hot-fire tests, accumulating 46 seconds of total firing time at temperatures nearing 6,000 degrees Fahrenheit while burning liquid oxygen and gaseous hydrogen.
"We saw no difference in performance of the 3-D printed injectors compared to the traditionally manufactured injectors," said Sandra Elam Greene, the propulsion engineer who oversaw the tests and inspected the components afterward. "Two separate 3-D printed injectors operated beautifully during all hot-fire tests."
Engineers also tested a more complex assembly of 3D printed injector and thrust chamber liner made by Directed Manufacturing, Inc., of Austin, Texas.
"Rocket engines are complex, with hundreds of individual components that many suppliers typically build and assemble, so testing an engine component built with a new process helps verify that it might be an affordable way to make future rockets," said Chris Singer, director of the Marshall Center's Engineering Directorate. "The additive manufacturing process has the potential to reduce the time and cost associated with making complex parts by an order of magnitude."
Rocket injectors for early SLS acoustic tests took six months to fabricate, had four parts, five welds and detailed machining and cost more than $10,000 each. Engineers built the same injector in one piece by sintering Inconel steel powder with state-of-the-art 3D printer in just three weeks for less than $5,000.
"It took about 40 hours from start to finish to make each injector using a 3-D printing process called selective laser melting, and another couple of weeks to polish and inspect the parts," explained Ken Cooper, a Marshall materials engineer whose team made the part. "This allowed the propulsion engineers to take advantage of an existing SLS test series to examine how 3-D printed parts performed compared to traditional parts with a similar design."
NASA said the SLS injector tests are just one example of its efforts to fabricate and test 3D printed parts in relevant environments similar to those experienced during missions. The test series complements a series of liquid oxygen and gaseous hydrogen rocket assembly firings at NASA's Glenn Research Center, which tested an additively manufactured laser melted injector.
"At NASA, we recognize ground-based and in-space additive manufacturing offer the potential for new mission opportunities, whether printing rocket parts, tools or entire spacecraft," Singer said. "Additive manufacturing will improve affordability from design and development to flight and operations, enabling every aspect of sustainable long-term human space exploration."