When the U.S. Army needed a Kiowa helicopter for a raft of tests to hone the aircraft’s military performance, it didn’t rescue a helo from the scrap heap and repurpose it.
Instead, the Army turned to NASA Langley Research Center in Hampton, where engineers downloaded computer-aided design files to a 3D printer and began to crank out a scaled model of a helicopter, layer by layer, piece by piece.
And when technicians snapped those pieces together, they had a plastic model of a Kiowa at 37 percent scale to run through rigorous tests in their subsonic wind tunnel.
Last year, NASA administrator Charles Bolden sent a congratulatory message to Langley’s Kiowa team telling them the project represented more than a “demonstrable savings on actual flight tests.”
“It also represents a significant reduction in risk to test pilots and test flight engineers who would have had to fly some of the high-risk ordnance carriage and delivery profiles had we not been able to model them as part of this project,” Bolden wrote.
Building aircraft models for wind tunnel tests is but one way engineers and researchers in Hampton Roads are harnessing 3D printing technology, which has grown beyond just making plastic Lego-like parts.
NASA Langley has a stable of a dozen or so 3D printers that work with powdered metal or metal wire, with resins, plastics and even wax. By depositing layer upon layer of plastic or by melting metals with an electron beam or laser, machines can grow objects from tiny widgets to pieces 3 feet across. With some systems, they can adjust various alloys to tailor for strength, rigidity and flexibility. They can build pieces so intricate that even the most skilled machinist can’t replicate them.
And they can do so at minimal waste and a fraction of the time and expense of conventional manufacturing methods.
“If someone comes in and they want a bracket for an airplane that they’re going to fly out in the desert or fly over Iceland or Greenland, we’ll make it for them,” said Nancy Holloway, head of the center’s Fabrication Technology Development Branch. “If they want a part or a whole model for a wind tunnel, we’ll make that. It can be something simple and almost trivial to something big and complex that can take months to build.”
Anything you can think of
3D printing — also called additive manufacturing — has been around for decades, but the technology is still being developed and improved for scientific, military and commercial use.
Astronauts, for instance, have just unpacked the first zero-gravity 3D printer ever to make it to the International Space Station, a demo version designed and built for NASA by the California-based startup Made In Space that sits inside a sealed chamber and can churn out simple plastic pieces.
The goal is to improve the technology enough that one day space station crew members can make hardware or replacement parts on the spot, rather than have them rocketed up from Earth at huge expense.
Printers range from relatively inexpensive desktop hobbyist machines that run a few thousand dollars to mammoth versions that work in powdered metals and go for three-quarters of a million dollars.
At Jefferson Lab in Newport News, Brian Kross purchased a $2,500 MakerBot two years ago to craft plastic instruments and parts for his Radiation Detectors and Medical Imaging Group. He figures the machine has paid for itself countless times since.
For Duke University’s research into how carbon dioxide moves through plants, for which Jefferson Lab provides instrumentation, they needed 80 components to build positron emission tomography (PET) plant root cameras. Each component would have cost $500 using traditional machining methods at $50 an hour in labor, for a total cost of $40,000.
Instead, the MakerBot cranked them out for the cost of the plastic, which runs $100 for a spool of about 4 pounds of filament.
“So this machine paid for itself on that very first project,” Kross said. “And once you have this thing around, you would not believe how many things you can think of that you need.”
The printer is in almost constant use, he said, capitalizing costs down to pennies on the hour.
The MakerBot works much like an ink printer, except it extrudes a plastic filament, laying one molten layer atop another to craft whatever the computer-aided design, or CAD, file has instructed.
Kross said he can program a CAD model in minutes or hours, depending on the complexity of the final product. CAD programs are also available online. Once prohibitively expensive, many are now available at minimal cost and some are free.
The cheaper MakerBot has its limitations, Kross said. Unlike its more expensive iterations, it can’t build cantilevered shapes very well, for instance. It also lacks the feedback option that’s encoded in professional models and can be finicky to operate.
But it has inspired innovation, enabling researchers to try out new designs and shapes that would have been far too complex or costly before: a form-fitting handle for a surgical probe or a tiny device that affixes tiny sensors to a mouse’s face.
“A lot of people at the lab have come knocking on our door, saying, ‘Will you make us a widget?'” Kross said. “And we’re trying to get the lab to adopt this on a larger scale.”
The problem? A professional model of a 3D printer starts at around $30,000, and money is tight.
“Right now we’re sort of in a dark period for budgets,” Kross said.
‘Build the impossible’
In the Additive Manufacturing Center at NASA Langley, specialists have built hardware and test articles for its mission directorates — aeronautics, Earth science, space technology and exploration.
“One of the biggest benefits to 3D printing is complexity,” said additive specialist Gary Wainwright. “The more complex something is, the more time-saving 3D printing is compared to conventional manufacturing. Where 3D printing really shines is, you can build something that is perforated with hundreds of holes and make shapes that are extremely complex, and it doesn’t add anything to the cost.”
In fact, he said, 3D printing saves money and materials.
“The cost savings is very large,” Wainwright said. “What has probably more importance to us is, some of the things you can build with this technology you can’t build with normal machining.”
“On a good day,” said Holloway, “you can build the impossible.”
On display tables at the manufacturing center are examples of the range of the technology:
*Wind tunnel models of the X-48C — a next-generation blended-wing body airliner — and the cutting-edge launch-abort system that sits atop the new Orion space capsule intended to carry astronauts deep into space;
*Mock-ups of Earth science instruments bound one day for the International Space Station, and a mold of the mushroom-like inflatable heat shield that helped the Curiosity science rover land safely on Mars;
*And metal demonstration pieces that showcase the unique capabilities of additive manufacturing — hollow, triangular nozzles that curve and twist, tubes that loop into knots, and filigree spheres.
“You can see the triangular channels here,” Holloway said, holding the polished, finished piece. “A good machinist could cut and machine the outside, but there’s no machine or machinist that can cut that triangular spiraling channel. The only way to make a part like this would be to grow it, layer by layer.”
How they grow
NASA Langley has two 3D printers that grow pieces using powdered metals, and one that’s fed with metal wire.
The two that work with metal powders, called selective laser printers or SLMs, are kept in a separate room to prevent accidental cross-contamination, said Holloway. An SLM drops metal powder into a hopper, spreads it flat, then hits it with a laser that melts the metal, throwing off sparks as it moves.
The Electron Beam Freeform Fabrication machine, or EBF3, also sits in a separate building, housed within a huge vacuum chamber to keep the electrons from scattering so they can focus instead on a wire fed in from the side and onto a plate, much like in welding.
With the EBF3, there’s plenty of movement going on, said materials research engineer Marcia Domack. The electron beam gun moves even as the table moves, rotates and tilts.
“It’s six degrees of freedom,” Domack said. “So we have the ability to build some complex shapes.”
What they’re primarily looking at, she said, are the structural applications of different alloys, figuring out how to change and control the properties to give each structure just what it needs.
NASA Langley is working with various aircraft industry partners drawn by the prospect of custom materials and parts at significant cost-savings.
A tail rudder spar, for instance, typically starts as a 3,000-pound unit of titanium that’s machined down to about a 350-pound part, explained materials engineer Karen Taminger. But by building it up from molten metal, companies are spared six weeks of machining and about $1,000 per pound of waste titanium.
“They end up with the same geometry, the same properties,” Taminger said. “It’s just a different way to get there.”
One challenge of the technology is the many opportunities for hidden flaws, she said, since the process involves building layer upon layer. That prospect can delay safety certifications for projects involving manned flight, but NASA is working to bring cameras inside the machine to inspect in real time as the material is deposited so that one day it could have an inspection report in hand as soon as a piece is done.
Taminger said EBF3 technology is also well suited for space-based manufacturing, since space itself is a vacuum. They’ve already successfully tried out the technology in zero gravity using an aircraft that can simulate weightlessness.
They hope to build on the excitement accompanying the plastic 3D printer that just arrived at the space station, she said, especially since plastic has its limitations for building structures, including habitats.
She said NASA already has designs for small metal 3D printers that could fit inside — and outside — the station.
Dietrich can be reached by phone at 757-247-7892.
