Above: GKN Aerospace is collaborating on the Ariane 6 launch vehicle, being built by the European Space Agency and scheduled for service in 2020.

Additive manufacturing allows a Tier I supplier the freedom to redesign ‘the whole system.’

September 2017 - You couldn’t get a better endorsement for 3D printing than from a company that has five technology centers scattered across the globe, each studying and perfecting methods that promise to disrupt the traditional ways of making big things that require long lead times from concept to production.

GKN Aerospace, part of GKN plc in Redditch, United Kingdom, is by all measures at the forefront of the additive manufacturing (AM) revolution. Its customers are the largest international builders of aircraft and spacecraft and many of its AM parts are being tested and OEM-approved and soon will be brought to commercial scale.

In June, for example, GKN Aerospace delivered the first advanced Ariane 6 nozzle to Airbus Safran Launchers in France for the Vulcain 2.1 engine. Large-scale use of laser welding and laser metal deposition (LMD) for key structural features resulted in 90 percent reduction of component parts, taking it from about 1,000 parts down to 100 parts.

GKN Aerospace is a contract supplier to Pratt & Whitney. Shown: Production of the 1100G turbofan gear at Pratt & Whitney’s Middletown, Connecticut, factory.

A demonstrator nozzle withstood a trial in a full-scale engine nozzle test as part of the European Space Agency’s Ariane Research and Technology Accompaniment Program. The flight configuration nozzle will next be tested on the Vulcain 2.1 engine in Germany. The Ariane 6 launch vehicle is scheduled to enter service in 2020.

GKN Aerospace will manufacture the nozzle in a new, automated factory in Trollhättan, Sweden, scheduled to open next year.

Strategic aims

The Ariane 6 nozzle is just one product in development at GKN Aerospace and at sister operations that include Driveline (automotive) and Powder Metallurgy.

“The work of building parts, components and systems often begins with rapid prototyping, primarily focused on metals,” says Dr. Rob Sharman, global head of additive manufacturing for GKN plc. “We are working all across spectrums of AM technologies: laser powder bed, binder, powder deposition and wire deposition. Our strategy is that additive creates a shift on how to design and build. We are leveraging the power of additive to design and build products radically differently. We have parts certified and flying right across the AM process spectrum from deposition to powder bed technologies.”

GKN is merely at the beginning of a journey, notes Sharman. The company is quickly using AM as a “faster and cheaper” successor to traditional manufacturing methods. Further, “we are using it to make things that couldn’t be done before. AM allows you to look at the whole system and the functionality” of a complex component and its production process. “It offers freedom to redesign the whole system, not just parts.”

3D printed components produced at GKN Aerospace’s Center of Excellence in Filton, United Kingdom, demonstrate how intricate the designs can be.

Laboratory partner

GKN Aerospace and the U.S. Department of Energy’s Oak Ridge National Laboratory in June signed a five-year research pact focused on additive manufacturing. Using the lab’s Manufacturing Demonstration Facility, this cooperative R&D agreement, valued at $17.8 million, will advance the family of “hugely promising” additive manufacturing processes, supporting progress towards their use in the manufacture of major structural components for aircraft.

Sharman calls Oak Ridge “a great place for additive research. It has great people to work with and world-leading capabilities, specifically around wire deposition.”

In league with GKN’s five global Centers of Excellence, the DOE partnership will “push the boundaries,” Sharman says, noting that wire deposition is “already in production in our space and aero-engine businesses.” With the technology, GKN will “build larger components and optimize parts.”

To date, most powder bed manufacturing cells have been small. “The big savings comes with large components—that is where the weight comes off,” Sharman says. Each of GKN’s five R&D centers tackle a different AM technology. Its New Jersey site is working on both metallurgy and powder research, developing powders and materials for AM.

“We have a powder bed center of excellence in Filton, England, and another in Sweden focusing on wire and powder deposition technologies. In Germany, we have a center working on laser powder bed predominately for the automotive industry,” he says.

An additively manufactured excavator stick, made of low-carbon steel weld wire on a MIG welding arm, was produced at Oak Ridge National Laboratory.

OEM partner

An ongoing partnership between GKN and Saab Group’s Defense and Aerospace business has already resulted in the delivery and certification of AM components now flying on multiple Saab aircraft. The work with Saab has focused on metallic powder bed technology, delivered from GKN’s center of excellence in Filton.

Alongside this partner, Sharman says, “We are all moving the technologies forward from substitution and how to push the boundaries of the technologies. At the moment it is focused on powder bed. We cannot reveal the exact products that have been certified for flight but they are in production and are flying.”

Besides the parts flown on Saab-built components, “we have proved commercial potential for each one of the processes”: powder bed fusion, fine-scale deposition, large-scale deposition (wire), materials development, binder and powder activity. “Each one of the processes has a sweet spot for different materials and applications, just like the range of different casting methods and their applications, Sharman says. “But it’s worth saying that we are just at the start of a revolution.”

The manufacturing supply chain itself may have to evolve to accommodate this revolution. “Today, one can use a machine that is slow, temperamental and produces only batch amounts, with alloys and materials that are not designed for the process, but I can still get good product out of it,” he continues. There are many opportunities for these processes to improve at each step along the value chain. “The machines are improving, the materials are improving, the processes are improving and the markets will open up with each step of improvement.”

GKN Aerospace delivered the first advanced Ariane 6 nozzle  for the Vulcain 2.1 engine in June. The nozzle measures 8 feet, 2 inches in diameter and was manufactured using laser welding and laser metal deposition for key structural features.

Step by step

According to Sharman, the first step to commercializing AM is proving the materials and processes in flight. Step two is to “make it work cost-effectively, timely and improve the processing methods.” Multiple case studies prove that machined castings can go from a solid to a flight-worthy part.

“The real value proposition [of AM] is amalgamating multiple parts and seeing efficiency improvement. AM is about not  what you can do today, but what you can create tomorrow. We expect the market to significantly grow, but it will vary by efficiencies.”

He compares AM to the IT revolution of the 1980s. “We had dot matrix printers and slow scanning. Today, laser printers turn out high-quality images every day. The pace of change is applicable to all sectors of manufacturing. Machine developments are moving rapidly. And it will benefit the whole manufacturing market.”

Leveraging integration

“We aren’t just about aerospace, but all sectors, including automotive. Our powder research facility is developing new materials for AM,” Sharman says. “The process is challenging—a blessing and a curse. The curse is the huge number of variables that can change, which makes it hard to get it right. Anyone can print shapes, but they are pieces of art unless they are engineered for strength, yield and mechanical properties.”

Generating the materials and the part simultaneously is like an acrobatic performance.

A robot sits inside the work cell that uses laser metal deposition with wire at Oak Ridge National Laboratory, developed with GKN.

“You must understand the material, the process and the geometry of the application to successfully make a component. We don’t start with the shape; we start with the material and make that right. To sit on an aircraft, a rocket, a car or train, it cannot merely look good,” Sharman emphasizes. “It has to be good inside—the material properties and quality have to be good, too. We link it all together.”

The blessing, he says, comes when you can understand each process parameter and variable and how the relationships work. In that case, you become able to reverse engineer starting with what you want or need the material properties to be, and then manipulate the process variables to deliver what you want. Then you can start playing with materials and move away from bulk materials.

Scientific insight

GKN, like many scientific organizations, is turning to the natural world for inspiration.

“Nature doesn’t make anything out of bulk material,” Sharman notes. “Look at steel girders—a tree doesn’t do that,” i.e., mass produce branches out of bulk material properties in straight lines. Instead, it generates its building material on a cellular level.

“It’s a far, long way into the future but that’s where additive manufacturing could take us. Nature tends to get it right; it’s had a lot more practice! Additive has the potential to  mimic that organic development.”

Meanwhile, he believes GKN has technological advantages because it capitalizes on the three key links: “We have the materials knowledge and capability, the design capacity and product knowledge as well as the processing knowledge. Together we make it work.” MM