How Metal Additive Manufacturing is Changing the Aerospace Industry Landscape

The aerospace industry has always been a difficult market for start-ups to break into, going all the way back to Glenn Curtiss and the surprisingly litigious Wright Brothers. Today, the challenge doesn’t come from intellectual property or competing with giants like Boeing and Lockheed Martin—there’s an entire supply chain feeding those behemoths, after all.

The real challenge for start-ups comes from the fact that the aerospace industry demands complex, expensive components made to rigorous standards and manufactured at low volumes. However, as in any industry, the introduction of new technologies has the potential to change the dominant paradigm. This is currently the case for additive manufacturing (AM) in the aerospace industry.

“The additive industry is preferentially aligned to the rocket industry, in terms of making very complex and high demand parts at low volumes,” said Dr. Youping Gao, Founder of aerospace additive manufacturing start-up Castheon. “That’s why there are so many start-ups in the rocketry industry today that are all based around additive manufacturing especially for the rocket engines (there are 88 of them when the additive manufacturing emerged as main stream manufacturing processes since 2010).  Without additive, I don’t think those companies would exist.”

Metal Additive Manufacturing Misconceptions

Gao has a unique perspective on this emerging shift in the aerospace industry, not only because he’s running his own start-up, but because he worked at Aerojet Rocketdyne for more than two decades. During that time, as Technical Fellow and Discipline Chief for Manufacturing Engineering, he conducted extensive research on metal manufacturing and particularly additive manufacturing. “When we look at the state of the metal AM industry—and I say this after many years of working in it—you can see that the technology is ahead of the science,” Gao said.

In other words, we can do a lot more with metal AM than we might realize. The reason for this, according to Gao, is a lack of understanding when it comes to the fundamentals of metal AM. This carries over in subtle ways, as he explained: “It started with people calling the process ‘direct metal laser sintering’ even though it’s not sintering, because sintering converts powdered material into a solid without melting.”

(Image courtesy of Concept Laser.)

One of the most basic misunderstandings in metal AM concerns the characterization of what’s known as the laser sintering process.  Gao noted that the consensus view is that laser additive manufacturing is a form of micro-casting, despite the fact that it operates based on the principle of welding.

“The key difference is that in welding, the transient heat source melt and solidify the materials rapidly.  While in casting, it’s an equilibrium or quasi-equilibrium process (slow process), where nucleation, different alloying constituents partition during grain growth phase dictate the microstructure and defects formation.  Where in welding or additive manufacturing, epitaxial growth (without nucleation) and followed by competitive grain growth dominate this process.  As the result, the different alloying constituent’s partition has been suppressed and supersaturated solids can be obtained in large and complicate structures which is unobtainable before the AM emergence.  This has setup the stage for superior AM materials performance and new alloys for the AM industry.”

It’s these kinds of insights that led Dr. Gao to start his own company, Castheon, which specializes in AM for higher temperature alloys and refractory materials for space applications.  The chance he took in starting this company speaks to his belief in the potential of additive manufacturing.

Banking on Metal Additive Manufacturing

Castheon grew out of Gao’s many years of research in manufacturing, which had already made a major impact on additive manufacturing in the aerospace industry. In 2015, Aerojet Rocketdyne was the first company to receive NASA certification for additively manufactured mission-critical hardware for manned spaceflight. That certification was the result of years of intensive research and development, which began in 2011 when the company acquired its first in-house additive machine, a Concept Laser M2 cusing.

“The alloys we wanted to try were ambitious,” Gao explained. “There were no parameters for them yet, so we had to develop them ourselves.” Fortunately, the M2 cusing’s open architecture gave Gao and his colleagues the necessary control over the machine’s process parameters to do that work. Their research gave the Aerojet Rocketdyne team many unique insights, though not all of these were practical to implement.

Nevertheless, it was this research and his enthusiasm for it that led Dr. Gao to start his own company. “What we realized was that there are certain materials that are ideal for additive, and where the traditional mill process cannot produce the same material properties,” he said. “I was so excited by these results, and if you’re an immigrant to the United States, there’s always that dream of becoming an entrepreneur.”  Two high acclaimed professors Erwin Rudy and Jack Devletian which have influenced Dr. Gao’s career development have worked at Aerojet and Rocketdyne, respectively, back when the two entities were fiercest competitors to each other.  Dr. Rudy immigrated to the United States from Austria after accepting an offer to establish and head new materials laboratory for Aerojet.  He later founded Sintex Pacific Hard Metals Corporation in Forest Grove, Oregon. 

The realization of Gao’s dream began with the acquisition of another Concept Laser M2 cusing machine.

“After doing those initial in-depth studies, I wanted to continue the R&D work,” he said. “That prompted me to acquire my own Concept Laser M2 cusing machine—my wife calls it my ‘toy’—because I wanted to continue to tinker. In a corporate setting, there are a lot of rules and procedures to follow and the urgency is to establish standard production process for hardware production, so the goal is to get the process working well for production and leave it alone “don’t mess with it”. But if you’re a tinkerer, you always want to do more.”

And so began Castheon, an AM process developer and service bureau that originated with aerospace but now serves every industry.  As an early adopter of metal additive manufacturing back in 2011, Dr. Gao has had years of experience to refine his methods.  That’s why his company is able to produce high-quality metal parts on the first print, rather than the second, third or fourth try.  It’s the kind of optimization that you can only get from years of tinkering.

Most engineers will no doubt be familiar with the compulsion to tweak and fiddle with a process in service of optimization, as well as the frustration that often comes from being unable to do so in a corporate setting.  For Dr. Gao, the freedom to tinker required a significant investment. “I took out a second mortgage and sold all of my stock investments and retirement funds” he said. “It was a risk, but I took it because of my passion for additive manufacturing.”

That risk appears to be paying off, as Castheon has already increased its capacity to three M2 machines to satisfy customer demand.

A Metal Additive Manufacturing Start-Up

Anyone with experience in AM—especially metal AM—knows that using 3D printing as a production technology involves a lot more than just having a 3D printer. In addition to the capital cost of the machine itself, there are operating costs associated with the necessary post-processing equipment. This presents a problem for a small start-up.

“Additive cannot stand by itself as a manufacturing process for anything—even just removing the parts requires a saw or wire EDM—and that can be a strain for a small company,” Gao explained. “That was especially true for me with Castheon.  I have two sons in college and my little one is in pre-school which costs almost as much as the third college when I decided to start Castheon but if I wait, the opportunity may not exist again.”

Castheon recently moved into a new 4,200 sq ft facility in Thousand Oaks, California which houses 3 Concept Laser M2 cusing machines. (Image courtesy of Concept Laser.)

True to engineering form, however, Gao managed to turn a potential problem to his advantage. Since Castheon couldn’t afford to purchase an industrial saw or wire EDM in addition to an M2, Gao redesigned his solid support structures that can be peeled apart by simple hand tools, making it easier to remove parts from the build plate. “It’s similar to how you open a can of SPAM with a key,” Gao said. “When you have a constraint, you figure out how to work around it. That’s why I designed the supports so you can prise them out with a pair of needle-nose pliers.”

This sort of expertise has given Gao a leg up when it comes to running an aerospace start-up. Between the relative novelty of the additive process and the extremely tight tolerances required by the industry, a less-experienced company could be misled by advice based on a misunderstanding. Gao describes this kind of problem as a gap between the science and the technology of metal additive manufacturing, where capabilities exceed understanding.

(Image courtesy of Concept Laser.)

Closing this gap between the science and technology of additive manufacturing is Castheon’s ultimate goal. “We want to be an enabler to the additive industry—to make metal AM widely adopted across the board, and to provide a scientific basis for best practices,” Gao said. It almost goes without saying that establishing a common set of best practices will be vital to the growth of the metal additive industry.

If Castheon can provide that basis, it will have done a great service to metal AM users everywhere.

Getting Into Metal Additive Manufacturing

Even though metal 3D printing is changing the aerospace landscape, there are some truths that remain regardless of industry. Based on his experience with Castheon thus far, Gao had two important pieces of advice.

(Image courtesy of Concept Laser.)

“Get well funded from the start—I was not, and it was a struggle,” he said. Fortunately for Gao, GE Capital recognized Castheon’s potential and provided additional funding, enabling the business to obtain more capital at affordable rates. “Also, buying the right machine is only half the challenge. This is not like ten years ago, when Rocketdyne started doing additive work. Back then, there weren’t a lot of alternatives, so people would come to us. Today, there are plenty of additive companies out there, so marketing is essential.”

For more information, visit the GE Additive  website.

Written by:  Ian Wright, for Engineering.com.