Metal AM Blasts Off with Award-Winning Rocket Nozzle Liner
Category: Manufacturing Technology • By: Benjamin Moses, Director of Manufacturing Technology - AMT The Association For Manufacturing Technology • Nov 18, 2021
Bhaskar Dutta dreams big – like 10 ft. and 2 tons big – and his dreams are winning awards.
As president of DM3D Technologies, Auburn Hills, Mich., Dutta led a team that used the company’s Direct Metal Deposition (DMD) (a form of Directed Energy Deposition (DED)) AM technology to print a full-scale RS-25 rocket engine liner nozzle under the auspices of NASA’s Rapid Analysis and Manufacturing Propulsion Technology (RAMPT) program.
Made from JBK-75, a stainless-steel, hydrogen-resistant superalloy used by NASA for nozzles and manifolds, the AM liner may ultimately become a component of the Aerojet Rocketdyne RS-25 nozzle for the space shuttle’s successor, the Space Launch System. DM3D’s nozzle liner has the same dimensions as the shuttle’s iconic, bell-shaped shuttle nozzles.
At the recent RAPID+TCT Conference in Chicago, DM3D received the prestigious Aubin AM Case Study Award from SME. The award panel notes that, “To print this part, significant advancements were made to the DMD technology that doubles the process throughput, scales the technology significantly and [couples it] with process simulations to make large-scale parts that were not previously considered feasible.”
“I believe we won the Aubin award not just because of the scale of the RS-25 liner, but because it shows the potential for handling difficult materials in very demanding applications,” says Dutta.
“Compared to forging, spinning, and ring rolling, the traditional methods of liner production, the AM liner compresses the supply chain and makes it more local,” says Paul Gradl, RAMPT co-principal investigator and a senior propulsion engineer at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “For parts such as the RS-25 liner, we can achieve a 2-to-10 time schedule reduction. Schedule compression reduces inherent cost, but we also see other cost reductions that generally amount to 50%.”
DMD technology integrates two 5kW industrial lasers, powder metallurgy and CAD/CAM to create a unique “near net shape” deposition process (see video). The high energy generated within the laser beam, when combined with the injection of complex alloy powders into the laser beam, deposits a molten weld pool on a freestanding substrate. As the particles fuse, closed-loop sensors monitor the melt pool to maintain dimensional integrity. Depositing successive layers of metal requires a minimum of heat transfer. This preserves mechanical and metallurgical properties, making DMD attractive for aerospace components, as well as additive metal changes to production tooling surfaces.
Unlike laser powder bed fusion (L-PBF) or binder jetting, DMD technology does not require the entire build chamber to be filled with metal powder and, therefore, is more material efficient. This, along with its higher build rate, makes DMD a better fit for applications that require larger parts where process time is critical. Using JBK-75, a difficult material to fuse, deposition rates of 6 to 8 lbs./hr. can be achieved. DMD technology works with a wide range of engineering alloys, and with some of these alloys it may offer deposition rates exceeding 10 lbs./hr.
“DED technology as a whole has the ability to produce parts at a very large scale compared to powder bed fusion processes, and it allows us to integrate and advance this process to supplement our current manufacturing methods,” says Gradl.
To develop the nozzle, DM3D partnered with Auburn University's National Center for Additive Manufacturing Excellence (NCAME) on its additive manufacturing (AM) research and development project with NASA for improving the performance of the liquid rocket engines. The DM3D, Auburn, and RAMPT collaboration are one example of the many public-private partnerships available through NASA.
“One of our missions is to help develop new technologies that industry may not necessarily invest in because there’s not an immediate return,” says Gradl. The RAMPT program requires a minimum of 25% industry investment, but the collaboration enables the government to take on some of the risk so that it can push the envelope to create a new national asset, new material, or new process.
“Our goal is to increase the technology readiness level, or TRL, so that the commercial space industry or other industries can then infuse the technology into their applications,” says Gradl.
Dutta notes that the latest RS-25 nozzle liner has just begun the development and qualification process.
“We are at TRL 3, which is the proof-of-concept stage,” says Dutta. “We learned we can successfully print a massive component and answered some fundamental questions, such as whether we have better success printing the bell-shaped nozzle bell end up or down” (it’s down).
Reaching TRL 5 requires hot-fire testing where the nozzle liner, as part of a system of components, will be subjected to the actual fuels and environment used during a flight.
"A full-scale additively manufactured nozzle liner demonstrator is a big milestone since not all processes are easily scalable,” says Gradl. “One of our goals for achieving a high technology readiness level is maturing the process for rocket engine applications and ultimately the implementation into flight applications”.
To explore the latest horizons and see how you can push the boundaries of 3D printing technology, visit the Additive Manufacturing Pavilion and AMT’s Emerging Technology Center at IMTS 2022, September 12-17, McCormick Place, Chicago.
For more information on Public-Private opportunities with NASA, visit:
About the Author
Benjamin Moses is Director of Manufacturing Technology at AMT-The Association For Manufacturing Technology. He worked in design and manufacturing world for aerospace components for 16 years, developing new products and implementing new and lean processes for legacy products. Benjamin now works with AMT’s Manufacturing Technology team to gather information about the latest technology research, concepts, and trends. This includes academic research and adoption of new technologies in manufacturing facilities. Through strong relationships with AMT’s membership, universities, and other industrial partners, AMT is able to gather a broad view on the state of manufacturing technology.