CFM International’s 3D-printed fuel nozzle. (Image courtesy of GE.)

The aerospace industry continues to find new applications for additive manufacturing.

Whether it is being utilized for making prototypes and parts at lower costs or for creating designs unachievable with traditional manufacturing, 3D printing has nowhere to go but up.

One area of focus shared by a variety of aerospace companies is the creation of engines using 3D printing techniques, and this is true from jet turbines to rocket engines.

Ranging from NASA’s emphasis on the creation of a completely 3D printed rocket engine to GE increasing its use of 3D printing in the manufacturing of jet engine parts. Even the Air Force has awarded a contract to SpaceX with an emphasis on increasing the use of 3D printing in their rocket engine manufacturing.

The use of 3D printing in engines has been seen by all of these companies and government agencies as a valuable investment. In all of these situations, laser sintering is the most popular 3D printing method for the creation of durable metal parts for aerospace engine use.





3D Printing Jet Engines

GE has one of the best known cases of incorporating of 3D printing into the manufacture of jet engines. In 2016, the company created the fuel nozzles for its new LEAP family of engines using direct metal laser melting. This turns thin layers of metal powders into fully-solid metal parts using a laser to melt the powder where the designers want the parts to solidify.

LEAP A1 engine. (Image courtesy of GE.)

3D printing allowed for the weight of the nozzles to be reduced by 25 percent, the number of the parts used to create the nozzle to be reduced from 18 to 1, and more intricate cooling pathways and supports, giving the nozzle a five-fold increase in durability.

These nozzles are no prototype. In April 2016, GE sent the first two production run LEAP-1A engines to Airbus with 19 3D printed nozzles included. LEAP engines using these nozzles are approximately 15 percent more fuel efficient than their counterparts.

The industry has been extremely receptive to these engines, with over 10,000 orders already in place, valued at around $145 billion.

At the end of December 2016, another major step forward was achieved for LEAP engines and their 3D-printed nozzles. The LEAP-1C jet engine was approved by the Federal Aviation Administration (FAA) and the European Aviation Safety Association (EASA).

Additive Manufacturing at NASA

Last year, NASA announced the achievement of an important milestone in the creation of a completely 3D-printed rocket engine. A series of 12 test firings were successfully performed on new NASA’s largely 3D printed rocket engine prototype at NASA's Marshall Space Flight Center in Huntsville, Alabama.

Graham Nelson, right, and Andrew Hanks examine a combustion chamber developed by engineers at NASA's Marshall Space Flight Center in Huntsville, Alabama, for an additively manufactured demonstration engine project. (Image courtesy of NASA/MSFC/Charles Beason.)

The fuel turbopump, fuel injector, valves and several other major components of the engine were all 3D printed. However, the project of creating the fully 3D printed engine is not complete, the primary holdout being the main combustion chamber.

Back in 2015, NASA completed an engine prototype 75 percent of which was made with 3D printed parts, as well as the first full-scale copper rocket engine part.

The test of this engine prototype used a combustion chamber which erodes during burn. This erosion changes the internal pressures of the engine, allowing for only a 10 second firing time. However, using the new (non-3D printed) combustion chamber in more recent tests, the engine was able to run for 30 seconds, with the ability to go longer if needed.

"A system is not just a sum of parts put together. It's a product of the interaction of the parts. What we're trying to do is understand and manage those interactions," said Nick Case, the project's lead system analyst. “At the same time, we must understand the performance of the individual 3D printed pieces. That's what this test allowed us to do."

This recent testing built on the team’s previous accomplishments, bringing them closer to the ultimate goal of a completely 3D-printed rocket engine. This final engine will have reduced time and development costs to comparable traditionally manufactured engines, incorporating some parts that could not be manufactured in a traditional setting.

"With our new chamber and the longer firings, we are able to create a test environment that is much closer to our design point for this project,” Andrew Hanks, test lead for the project said.

The team hopes to test a nearly 100 percent 3D printed engine system this year. This engine will serve as prototype that informs and influences commercial designs.

The next major step to achieving this will be the addition of a 3D-printed oxidizer turbopump, which is being fabricated as part of a collaborative development with the NASA Space Technology Mission Directorate’s Game Changing Development program.

This same program is also funding the development of a 3D printed combustion chamber.

Data on the materials characterization and performance for the 3D printed parts will be available in NASA’s Materials and Processes Technical Information System (MAPTIS) to approved users.





3D Printing at SpaceX

The use of 3D printing in engine development and manufacturing is no less prevalent in the commercial space sector.

In 2015, the US Air Force committed $241 million in combined contracts to Orbital ATK and SpaceX to develop rocket engine prototypes. SpaceX in turn is investing $67 million, with the purpose of developing a prototype of its reusable Raptor propulsion system.

Test firing the Raptor engine. (Image courtesy of SpaceX.)

The Raptor system is SpaceX’s most powerful engine and uses many 3D-printed parts, including the turbopump. One of the Raptor Engines tested by SpaceX last year was made up of over 40 percent 3D printed parts by mass.

This propulsion system is used in the upper stage of the Falcon 9 and Falcon Heavy rockets, and will likely be used in SpaceX’s future missions to Mars.

All of these powerhouse aerospace companies, as well government programs, focusing on the advancement of metal 3D printing for aerospace engine applications hints at 2017 being a big year for additive manufacturing.

Metal 3D printing is just at its beginning stages and is poised to grow to new levels in the aerospace industry and beyond.

For more on the future of additive manufacturing, check out Finding a Home for 3D Printing in Manufacturing