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NASA rocket engine igniter made of Inconel and copper by hybrid 3D laser printing
October 06, 2017
Source: ASM International
NASA Marshall Space Flight Center, Huntsville, Ala., announces that its engineers have tested the first 3D printed rocket engine igniter made of Inconel and a copper alloy. NASA has been making and evaluating durable 3D printed rocket parts made of one metal, but the technique of 3D printing with more than one type of metal is more difficult.
For this prototype igniter, the two metals – a copper alloy and Inconel -- were joined using a unique hybrid 3D printing process called automated blown powder laser deposition. The prototype igniter was made as one single part instead of four distinct components that were formerly brazed and welded together in the past. This bi-metallic part was built during a single process by a hybrid machine made by DMG Mori in Hoffman Estates, Illinois. The new machine integrated 3D printing and computer numerical-control machining capabilities to make the igniter.
While the igniter is a relatively small component at only ten inches tall and seven inches at its widest diameter, this new technology allows a much larger part to be made, and enables the part's interior to be machined during manufacturing—something other machines cannot do. This is similar to building a ship inside a bottle, where the exterior of the part is the "bottle" enclosing a detailed, complex "ship" with invisible details inside. The hybrid process can freely alternate between freeform 3-D printing and machining within the part before the exterior is finished and closed off.
"It is a technological achievement to 3-D print and test rocket components made with two different alloys," saya Preston Jones, director of the Engineering Directorate at Marshall. "This process could reduce future rocket engine costs by up to a third and manufacturing time by half."
Engineers at Marshall, led by senior engineer Robin Osborne of ERC Inc., low-pressure hot-fire tested the prototype more than 30 times during July to demonstrate the functionality of the igniter. The prototype, built by a commercial vendor, was then cut up by researchers at the University of Alabama in Huntsville who examined images of the bimetallic interface through a microscope. The results showed the two metals had inter-diffused, a phenomenon that helps create a strong bond.
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