Sep 19, 2017 | By Tess

NASA has successfully tested a prototype for a 3D printed rocket engine component made from two different metal alloys. The 3D printed rocket part underwent thorough tests over the summer at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

The component, a rocket engine igniter, marks the first time that NASA has been able to successfully combine two metal alloys in a functional part using 3D printing. Marshall engineers say this breakthrough could lead to faster development times and lower production costs for engine igniters in the future.

“It is a technological achievement to 3D print and test rocket components made with two different alloys. This process could reduce future rocket engine costs by up to a third and manufacturing time by 50 per cent,” said Preston Jones, the director of the Engineering Directorate at Marshall.

A rocket engine igniter, for those unfamiliar with the internal parts of a rocket, is used to trigger the engine’s start sequence. Traditionally, the critical engine component is made using a complex and laborious process called brazing, which combines two metals by “melting a filler metal into a joint [to create] a bi-metallic component.”

While an effective method, brazing can be a slow and expensive process, as it requires manual labor and various different steps to complete. By 3D printing two metal materials into a single part, NASA has opened the doors for a more efficient and cost-effective way to manufacture rocket engine igniters.

“Eliminating the brazing process and having bi-metallic parts built in a single machine not only decreases cost and manufacturing time, but it also decreases risk by increasing reliability,” explained Majid Babai, advanced manufacturing chief and project lead at Marshall’s Materials and Processes Laboratory.

Researchers examine a segment of the 3D printed igniter prototype

“By diffusing the two materials together through this process, a bond is generated internally with the two materials and any hard transition is eliminated that could cause the component to crack under the enormous forces and temperature gradient of space travel,” he added.

The part itself was made from a copper alloy and Inconel, which were combined using “automated blown powder laser deposition,” a hybrid 3D printing process developed by Illinois-based machining expert DMG MORI which integrates 3D printing and “computer numerical-control machining capabilities.”

The engineers at Marshall were able to leverage DMG MORI’s hybrid additive system to produce the igniter part in a single print. The printed component, which measures 10 inches in height and 7 inches in width, is purportedly at the smaller end of what the 3D printer can manufacture.

Additionally, DMG MORI’s system offers a unique feature: users can choose to have their part’s interior machined during the printing process. In other words, the printer can go between additive manufacturing and machining in a single print, perfecting a component’s interior structure before its exterior is finished.

Testing for the part was carried out by a team of engineers at NASA’s Marshall Space Flight Center led by Robin Osborne, a senior engineer at ERC, Inc. The testing process consisted of over 30 low-pressure hot-fire tests, which were meant to show that the 3D printed igniter prototype was functional.

Microscope image of igniter cross section showing how both metals have inter-diffused

(Images: NASA)

After the numerous hot-fire tests, researchers from the University of Alabama were given the part to deconstruct and analyze. In the end, they found that the two metals that made up the part had inter-diffused well, and had created a strong bond in the part.

“We’re encouraged about what this new advanced manufacturing technology could do for the Space Launch System program in the future,” said Steve Wofford, manager of the SLS liquid engines office at Marshall. “In next generation rocket engines, we aspire to create larger, more complex flight components through 3D printing techniques.”

 

 

Posted in 3D Printing Application

 

 

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