By Jeff Newman
When the team of engineers standing on the flight line let out a cheer as an MV-22B Osprey took off outfitted with a 3-D printed flight-critical part last July, it was with the hope they had finally demonstrated the potential of additive manufacturing to revolutionize how the U.S. Navy maintains its platforms and equips its Sailors.
In the past year, the Navy has seen a surge in interest and experimentation with additive manufacturing (AM), and nowhere more so than in Naval Aviation, where the current initiative began in earnest with the development of a roadmap by the Naval Air Systems Command (NAVAIR) in September 2014.
Whereas traditional “subtractive” manufacturing involves bulk materials being cut or machined down into desired objects, additive manufacturing refers to the process of using 3-D printers to build objects in layers using materials like plastic polymers or powdered metals.
Using digital models, 3-D printers can create in hours objects that would normally take days or weeks while allowing for innovative designs that wouldn’t be feasible using traditional manufacturing methods.
And yet, while working to bring their first project—a 3-D printed link and fitting that secures an Osprey’s engine nacelle to its wing—from concept to reality, NAVAIR engineers initially encountered skepticism that their part could be as strong and safe as its traditional version.
The naysaying came to a halt after component testing proved it to be as sturdy, and in some areas more so, than the original link and fitting, and it flew aboard an MV-22B at Naval Air Station (NAS) Patuxent River, Maryland, July 29—marking the first time an aircraft had flown with a 3-D printed flight-critical part.
“That flight has driven a change and a shift in how we are looking at AM and how we want to scale it across the command,” said Liz McMichael, NAVAIR’s additive manufacturing and digital thread integrated product team lead. “We showed that we could do it, so now people want to know how to do this and whether it really scales. Do we have the right focus and priorities? Do we have the right processes in place to manage this? Not yet, but that’s what the roadmap is intended to address.”
As attention and support directed at additive manufacturing projects grew exponentially in the past year, and more ships and maintenance depots have acquired or expressed interest in getting 3-D printers, McMichael said it became clear there was a need for a workforce that understood the technology. To that end, NAVAIR has stood up innovation cells and ‘fab labs’—short for fabrication labs—across the organization so that Sailors, Marines and civilian engineers can learn what the technology offers.
“Unless you’ve really played with AM machines, you don’t understand how adaptable they are and how you might be able to use them in ways you haven’t thought about,” McMichael said.
As more Sailors and Marines are exposed to the technology, they are coming forward with additive manufacturing solutions for maddening readiness problems.
“Basically everybody we talk to, whether we come to them with a solution or they come to us with a problem, more projects come up,” said Giles Howlett, team co-lead at NAVAIR’s logistics innovation cell. “We have one idea, and they come back with two. There’s a lot of need for this kind of process.”
Printing Quick Fixes
The Navy recently signed off on one of the cell’s solutions—a 3-D printed version of an H-1 helmet visor clip that frequently breaks when Marines bump it into something—making it the first AM part in the Navy supply system approved for fleet operations.
The original clip, which secures the visor to the helmet, costs more than $300 a pop.
“I can make this one for 75 cents,” McMichael said. “If anyone asks, is there a business case for AM? Yes, there’s a business case for AM.”
In its search for projects, the innovation cell—now a year old after standing up May 2016—heard last winter that the H-1 program office was looking for a way to more quickly replace the clips. The process of designing and printing the tiny part began in earnest a few months later, and in April the cell had its clip approved.
Howlett sent an initial batch of 73 clips to the program office for approval in March, when it was discovered that an alignment hole was slightly off. The setback quickly morphed into a chance to showcase the speed enabled by additive manufacturing—upon hearing of the issue, Howlett was back at the cell, and had two redesigned clips printed out within four hours. Those clips were mailed out the same day along with four of the original design that Howlett fixed by hand.
“The strength of additive manufacturing is that I can make a design change and print it in a morning,” he said.
Howlett said the hope in the near future is to have the H-1 clip approved for the 3-D printer at Marine Corps Air Station Camp Pendleton, California, so that Marine Aviation Logistics Squadron (MALS) 39 can print its own clips as needed.
“Our goal as the innovation cell is to be the incubator, not to be a production facility,” he said.
The innovation cell is housed inside the Fleet Readiness Center Mid-Atlantic (FRCMA) hangar at NAS Patuxent River, putting its engineers steps away from the Sailors who make up the FRC’s own innovation team.
Together, the two groups are working on 3-D Sailor, a project aimed at saving money and ship space by 3-D printing the plastic components of flight deck gear, such as whistles, traffic wands, the front panels on cranial helmets, and the clips on Sailors’ float coats.
“We break these clips all the time, and you can’t get spares—you have to order the whole float coat, and they’re a couple hundred dollars apiece,” said Aviation Electronics Technician 1st class Michael Pecota, assistant team lead for the FRCMA-Pax River innovation team. “And because anybody shipboard that goes above deck has to wear them, they have to keep a lot of them on hand in case they break.”
Navy ships could put 3-D printers on board-a concept demonstrated on USS Harry S. Truman (CVN 75) in late 2015-and give the fleet the ability to quickly fix problems.
It only takes the team a few weeks to design the 3-D printed parts, with the goal being that Sailors in the fleet will then be able to take those designs and print their own parts on-demand while at sea. To that end, the teams are developing digital technical data packages (TDP) for each part.
Essentially a robust digital instruction manual, a TDP “encompasses everything that you need to print the parts successfully,” Pecota said. “What the tolerances are, how you verify that what you got is what was intended, how you make sure the file is accurate, all the infill diameters, all the information you need.”
Also, because 3-D printing is not currently a rating or skill taught in Navy training courses, the TDPs will come with a basic curriculum teaching Sailors how to use their ship’s printer.
Another aspect of 3-D Sailor is the implementation of a procedure to test the effects being at sea has on 3-D printers.
“How do 3-D printers react at sea during swell? The moving of the ship, does that vary it? Do you have to only operate them during low conditions?” Pecota said. “Temperature and humidity have a lot to do with the quality of your 3-D print as well, so do you need to have them in a separate room that is separated from those elements or are they okay in any space?”
Funded by the Navy’s Innovation Sustainment Group, 3-D Sailor also ties into another project the team is working on—recycling of shipboard plastics into 3-D printer filament.
While there are many plastics that can be melted down into filament, the focus is on polyethylene terephthalate—commonly abbreviated as PET—which is what water bottles are made of and carries the number ‘1’ as its recycling symbol. In textile applications, PET is better known as polyester.
On Navy ships, plastic bottles are melted down into large pucks and stored until port visits, when they’re offloaded and recycled, Pecota said.
“You can’t throw them overboard, you can’t burn them off, you store them until you pull into port,” he said. “But meanwhile, while you’re at sea between port visits, melting the plastic down stinks up the ship, and storing it takes up a lot of space.”
To turn the PET into filament, the bottles would instead be fed into a wood chipper-like machine and then fed into an extruder which pushes the chips into a heating element and produces long, thin strands that are then put on spools like fishing line.
“Those spools are used in the 3-D printers,” Pecota said. “So the benefit is, you’re still recycling all that waste, but now it makes those shipboard 3-D printing labs self-sustainable. They don’t have to buy more material, just reuse the plastics you already have on ship.”
Another project, one of Pecota’s favorites, is the 3-D printing of plastic plugs as a replacement for the metal honeycomb sheets—so called because they consist of hollow cells arranged in a honeycomb pattern, minimizing the amount of material and weight needed to provide reinforcement—that are currently used to patch any damage in an aircraft’s surface.
“Traditionally, when you dent or damage an aircraft, even if it’s a little dent, you have to bore out the section and hand-shape the honeycomb to fit the hole you’ve drilled, and then you seal it over with epoxy,” Pecota said.
The problem is, because the honeycomb is made of hollow structures and inserted vertically into the damaged section, the epoxy “seeps all the way through” filling each cell before sealing at the aircraft’s surface,” he said. This not only adds unnecessary weight, but wastes epoxy.
In place of the honeycomb, the innovation team is looking into plugs that can be 3-D printed with a honeycomb interior and solid surface, reducing the amount of epoxy needed to achieve a seal. In addition, instead of spending time cutting out honeycomb to fit drilled holes, Sailors could simply carry a few plugs that have been printed to fit standard hole saw sizes.
The two innovation teams have worked through projects at a brisk pace. When asked last summer to fabricate a small nylon clip that could be used to remove an F/A-18’s gun while in maintenance, the group was given five days.
“We did it in three days,” Pecota said.
Pecota credited that speed to the teams’ co-location.
“We’re not the only people that are doing this, but it looks like we’re moving the fastest, and it’s because of these guys,” Pecota said, pointing to the NAVAIR engineers in the room. “There isn’t too much from our team that’s different from any of the other fab lab teams except for the engineers and the Sailors closely working together. We come up with the ideas, and they tell us how to make them happen, how to implement them and keep things safe”
Pecota runs FRCMA Pax River’s communication navigation shop by day, but it’s quickly evident when he speaks about 3-D printers that he’s passionate about the subject. He owned his own printer well before the innovation team got one—when FRCMA didn’t have a 3-D printer for the additive manufacturing booth at the 2016 Sea Air Space expo, Pecota brought his own—and a cap he created to cover sensitive sensors on submarine-locating sonar transducers won the inaugural Athena DC 1.0 innovation challenge in May 2016.
“It’s the absolute greatest game changer to manufacturing. It allows anybody to do anything,” he said. “If you can think of something you can make better, maybe the end result isn’t going to be 3-D printed, but you can start there. You can come up with new ideas, new ways of doing things, and then you can take those ideas and physically touch them and make changes from there.”
Enabling ‘Engineering Agility’
Success stories elsewhere in Naval Aviation abound.
When the manufacturer of the T-44 Pegasus trainer exhausted its supply of a forearm-length piece of air duct tubing used to circulate oxygen throughout the cockpit, a tooling maker at Fleet Readiness Center Southeast in Jacksonville, Florida, used a 3-D printer to not only make the tubing for less money, but he improved on the design.
“The original piece was made out of two pieces of clear plastic tubing that had a flange all the way down its length,” said Randy Meeker, the tooling maker. “I redesigned it to work better than the plastic model. It didn’t need to be two pieces when I could print it as one piece.”
At Naval Warfare Center Weapons Division (NAWCWD) in China Lake, California, engineers used a 3-D printer to make an inlet for the solid-fuel ramjet engine they are developing.
Doing so “dramatically improved our cost and our time to get the inlet to us,” said Matt Walker, head of the Missile Performance Office at NAWCWD. “From a research and development standpoint, when you’re looking at small quantities, it definitely increases your speed and reduces your cost associated with making the parts,” Walker said. “We could probably go to a manufacturer to mass produce these for cheaper than we would do with additive manufacturing, but if we’re just going through concept development, additive manufacturing gives us a much less expensive alternative and rapid turnaround time to be able to test out our components quickly.”
Walker had long been interested in additive manufacturing as a way to build complex parts quicker and cheaper, so when NAWCWD got a new 3-D printer in September and was looking for projects to use it on, he was quick to offer up the ramjet.
“There was a little bit of churn until we figured out exactly how to layer the metals, what speeds we should be sintering the powders,” he said. “There were a number of things we had to learn in order to finally get this good product.”
That product ended up costing 40 percent less than it would have using traditional manufacturing techniques, and saw its production time slashed from four weeks to a week-and-a-half, said Nevin Hill, a mechanical engineer with NAWCWD’s Applied Manufacturing Technology Division.
“The exciting thing to take note of is that the non-printed air inlet is actually an assembly consisting of 14 separate pieces, whereas the printed piece is a single part printed all at one time,” Hill said. “Additionally, printing allowed for the engineering team to make design changes that both saved weight and increased system performance due to the more complex geometry we were able to produce via the metal printing process.”
Walker said 3-D printing allowed his team to precisely design the inlet’s internal contour so that it would channel airflow more efficiently.
“It gives us that engineering agility to be able to design without the limitations of traditional machining. That’s another advantage of additive manufacturing, that you can print—so long as its structurally viable—whatever shape you want, things that you may not be able to create with traditional machining, or without at least very complex traditional machining,” he said. “Because we’re not limited by traditional methods, it opens up the design space. We can pretty much print up whatever we can conceive so that the flow is optimized for highest performance.”
Walker said the printed inlet “performed fantastically” in free-jet testing in late March, better than the traditionally manufactured inlets that had been used in previous tests. His team’s first test flight came last summer, when the ramjet accelerated to Mach 2.
Later flights pushed acceleration to Mach 2.45, but the 3-D printed inlet’s performance in free-jet testing had Walker expecting the next flight to reach Mach 2.75 or a little higher.
“This is about as good as we can get with an axisymmetric inlet,” Walker said. “It would be hard to beat this.”
The Way Forward
Pecota said he could foresee additive manufacturing being incorporated into certain rates in the future, particularly machinery repairmen (MR), who already know computer-aided design (CAD)—a chief component of 3-D printing—in order to operate computer numerical control machines. But in the short term, he would like to see an AM certification program open to any Sailor with interest.
“It’s anybody who has an interest, who has an idea of something that could be made better through AM, they can take the class,” Pecota said. “Like right now, you don’t go into a rate to learn to operate some of the support equipment that we use. You just go to a class, they teach you how to operate the equipment, and you walk away with a certification saying you are certified to do that. I foresee that’s what’s going to happen here in the beginning.”
Pecota noted that the FRCMA cell has been offering unofficial, one-day classes on basic CAD and how to operate a 3-D printer with great success.
“We’ve found that people walk in with no idea what 3-D or CAD is, but because they walk out understanding what they can 3-D print, they have ideas about what their job or work center is missing,” he said.
In one example, some Sailors realized they could 3-D print eyewash caps to replace a few that had broken at the FRCMA hangar.
“So we did it in one day,” Pecota said.
Meanwhile, McMichael’s team has expanded its scope and taken on projects such as embedding sensors in 3-D printed components—something that can’t be done with traditional manufacturing techniques—allowing for better monitoring of a part’s structural health. Propulsion and power engineers are exploring the 3-D printing of sand cast molds.
“Castings are a big readiness issue,” McMichael said.
But more than anything, McMichael is focused on developing the chain of data needed to turn additive manufacturing into a full-blown supply system.
“AM is not about the machines. AM is about the data that we use to drive the machines and manage the process and the risk,” she said. “We need to understand and make sure that even if people assert data rights, as lots of industry does, that we know where that is and we are able to work with industry to pay them for their data rights. We want a digital warehouse, not just parts on a shelf, and that’s a business model change.”
Along the way, the Navy will need to learn “how to accept risk in the right way and figure out how we can get our time to field down from years to months to days, and really we’re talking about being able to do dynamic, on-demand manufacturing of whatever we need,” McMichael said. “If you do it wrong, it’s a safety risk. If you do it right and you follow the right process, it will help, and it will change readiness and improve the timeline to solve our problems by orders of magnitude.”
Jeff Newman is a staff writer and contributing editor to the Naval Aviation News magazine.