Additive manufacturing (AM) is gradually making its way into mainstream manufacturing, but in order to become more fully integrated for use in end parts, particularly in aerospace, there are still some issues to be addressed. One of those issues is repeatability.
Stratasys has announced at the 2017 Paris Air Show that it is on the path to ensuring consistency within parts printed with its flagship technology, fused deposition modeling (FDM). With modifications to its Fortus 900 system and ULTEM 9085 material, the company has introduced products currently being tested for certification and use in aerospace under Federal Aviation Association (FAA) standards.
In tandem with this news, Stratasys also announced that it has been chosen as a partner by Boom Supersonic to use Stratasys technology in the development of its supersonic aircraft, which aims to hit the skies in 2018.
ENGINEERING.com spoke with Scott Sevcik, head of Aerospace, Defense and Automotive at Stratasys, who shed light on these announcements and what they mean for 3D printing in aerospace.
3D Printing and Supersonic Air Travel
Denver-based start-up Boom Supersonic is in the process of developing a Mach 2.2 airliner that the company hopes will be economical enough to operate with business-class fares. Boom plans to make its first boom in 2018 with the XB-1, its supersonic demonstrator that, the company suggests will be capable of flying 2.6x faster than any other aircraft on the market.
In order to meet its quick-paced development schedule, Boom signed a three-year agreement with Stratasys and will deploy the Fortus 450mc and Stratasys F370 FDM systems. These machines will be used to speed up the production of tooling and production-grade aircraft parts.
“Boom is launching a very ambitious program to bring supersonic air travel back to the masses,” Sevcik said. “They’re going to be building a very fast plane and a very fast development schedule. A partnership with us and access to 3D printing for prototyping, tooling and production applications is a way that they have chosen to help accelerate the process of bringing their vehicle to the skies.”
Flying at up to 1,451 miles per hour, the XB-1 would be somewhat faster than the Concorde, which flew at 1,354 miles per hour, and cut the travel time from New York to London from seven hours down to just over three. Whereas the Concorde was decommissioned due to the cost needed to fly and maintain it, Blake Scholl, founder and CEO of Boom, believes that modern advances have made supersonic flight more feasible.
“Supersonic flight has existed for over 50 years, but the technology hasn’t existed to make it affordable for routine commercial travel. Today’s significant advances in aerodynamics, engine design, additive manufacturing and carbon fiber composite materials are transforming the industry at all levels. Additive manufacturing helps accelerate development of a new generation of aircraft,” Scholl said.
FDM 3D Printing for Aerospace
3D printing has been used in the aerospace industry since the technology’s inception. Sevcik pointed out that Stratasys has had one aerospace customer for 30 years. Throughout that time, AM and its applications have progressed steadily, beginning as a method for producing rapid prototypes to manufacturing aids and, most recently, end parts.
Sevcik elaborated on each of these applications, explaining that prototyping with FDM makes it possible for engineers to understand the look, fit, feel and function of a part, such as putting a 3D-printed model through win tunnel testing before taking the next step for mass manufacturing.
FDM is also increasingly used to produce low volume custom tools on the factory floor. These include fixtures, jigs, drill guides and check gauges that streamline the assembly and manufacturing process. “In many cases, every operation and assembly requires its own setup, its own set of fixtures in order to accomplish the assembly procedure reputably, and that can be incredibly expensive,” Sevcik said.
Although 3D printing has often been championed as a means of mass producing batches of individualized, custom items (a process referred to as “mass customization”), Sevcik said that mass customization may not necessarily require that these parts be 3D printed directly. Instead, the tooling itself can be customized with 3D printing before other manufacturing methods are employed to produce the final part.
By 3D printing the tooling, “you can start producing more different tools and customizing those parts that you produce, making unique parts for different customers or unique parts catered to specific applications,” Sevcik said. “The real value is to be able to do more for less. Introduce the opportunity for mass customization instead of relying on the economics of mass production.”
This extends to composite tooling, which is necessary for performing the costly and labor-intensive process of carbon fiber layup. According to Sevcik, traditional tooling for such an application can cost between $60,000 and $80,000 and take three or four months to obtain. By 3D printing the tooling, however, it can take just a few days to 3D print tooling that can cost only a few thousand dollars to make.
3D Printing End Parts for Aerospace
As evidenced by GE’s acquisition of Concept Laser and Arcam, 3D printing is now becoming sufficiently mature to produce end parts for use in aircraft. While GE Additive has focused on metals, Stratasys announced at the Paris Air Show that performance plastics are nearly ready to produce end parts, as well.
“The parts that are flying today are largely noncritical,” Sevcik said. “We have the initial qualifications for interior aircraft cabin parts that are designed to be nonloaded. They are noncritical parts that are doing the function of routing cables or providing covers or ducting.”
One issue that has prevented the next step toward adopting 3D printing for the production of plastic parts for use in aircraft is consistency and reliability, particularly along the Z-axis of printed parts. “We’ve got materials that are quite strong,” Sevcik explained. “What’s been needed in the industry is more consistency with the mechanical properties—having high confidence that the Z-strength is going to be the same every single time.”
To address the challenge, Stratasys has modified its Fortus 900 3D printer and its ULTEM 9085 material, a polyetherimide thermoplastic that has received a number of aerospace certifications for its high temperature resistance and strength. As a result, the machine, dubbed the Fortus 900mc Aircraft Interiors Certification Solution, and the material can demonstrate mechanical properties consistent enough for potential use in aircraft interiors.
“We really took a deep dive into the process for one of the most consistent, repeatable 3D printing systems out there, the Fortus 900, and looked at what is driving variability,” Sevcik said. “We then made changes to the extrusion process, both from a hardware and software standpoint. The way we deliver the material has changed, not dramatically, but in a way that allows us to reduce the opportunity for defects, which drive variability.”
To qualify the process and material, Stratasys has engaged with the National Center for Advanced Material Performance (NCAMP) within the National Institute for Aviation Research. Stratasys will then aid customers in qualifying the Fortus 900mc Aircraft Interiors Certification Solution for equivalency with the NCAMP statistical dataset.
“For 10 years, NCAMP has qualified composite material systems for use by the aerospace industry to certify under the FAA,” Sevcik said. “Now, for the first time, NCAMP is qualifying the FDM process on this updated Fortus 900 configuration under the Composite Materials Handbook-17 qualification process, so that there will be an industry-standard material specification, process specification and B-Basis Allowable dataset to leverage for certification.”
This means that, once the new configuration and material are qualified, Stratasys will be able to port the same technology over to other systems, such as the Infinite Build and Robotic Composite Demonstrators unveiled last year. In turn, it would be easier to then certify those systems as well.
The new Fortus 900 configuration is, according to Sevcik, already in the hands of a couple of customers who are producing the test coupons for the B-Basis Allowable program. “With the completion of testing this summer, we’ll begin delivering the systems more widely to move to the marketplace. Parts produced with this configuration could be flying this year,” Sevcik said.
Once process and materials are qualified and certified, it’s possible that customers will be able to begin using the technology to 3D print components for aircraft interiors. This will make it possible to fabricate parts that are out of stock, as well as create custom components that can differentiate an aircraft interior. Through topology optimization that is only possible with 3D printing, engineers will also be able to reduce the weight of a part, ultimately reducing weight on the aircraft and increasing fuel efficiency.
All of these advantages would likely be beneficial to an aircraft like the XB-1 from Boom. As important as it is for a plane to fly fast, it’s also important that it do so efficiently. If Boom can use FDM to make lightweight parts, it will be able to improve the fuel efficiency and reduce the price of a ticket. At that point, supersonic air travel really could begin to take off.
To learn more about Stratasys and Boom, check out their websites.