Although GE Additive may have become the star of metal 3D printing in the aerospace sector, British aerospace and automotive manufacturer GKN may have produced the most 3D printing-related aerospace news at the Paris Airshow last month.
After working with additive manufacturing (AM) technology for some time, GKN’s aerospace division decided to share with the public a number of achievements and partnerships the company has been up to, ranging from developing new metal AM technologies to producing novel components for rocket engines.
In the foreground is the Vulcain 2.1 demonstration nozzle, which is used for the Ariane 6 rocket and has over 50 kg of metal 3D printed onto the system. In the background is the Vulcain 2 nozzle for the previous Ariane 5 rocket. (Image courtesy of GKN.)
ENGINEERING.com spoke with Rob Sharman, global head of additive manufacturing at GKN, to learn about the company’s work in metal AM.
GKN Gets into Additive
GKN is a 5,100-person engineering firm and tier one supplier to some of the leading firms in aerospace and the automotive industry. According to Sharman, the company supplies critical airframe and engine parts to just about every major aerospace manufacturer, including the A350 wing spar, the canopy for the F-35 fighter, the wiring for the 737 and windows for Boeing aircraft.
“These are structural elements in aero engines and airframes,” Sharman explained. “We know how to develop highly critical engineering components and parts for the aerospace and automotive market. We understand the market, and we understand what it takes to get things flying. We had to learn to develop AM to meet those requirements.”
Sharman said that, about four years ago, it was decided that AM had a lot of potential for the company. In turn, GKN set up five Centres of Excellence devoted to different areas of 3D printing, including powder bed fusion, fine-scale deposition, large-scale deposition, materials development, and binder and powder activity.
Industrial AM technology is quite complex, and nailing down the processes to produce parts for critical aerospace applications requires a great deal of expertise. Since adopting the technology, however, GKN seems to have developed that expertise.
“Fundamentally, it’s all about the material and getting the material properties right,” Sharman said. “It’s getting your process control to be able to produce the right material properties, which is quite the challenge. A lot of people produce a lot of demonstrators and parts in the industry, and they have nice pictures, but unless it’s good quality with good engineering with good quality material in it, then it’s useless. It’s just a piece of art.”
3D Printing Parts for Saab
Demonstrating that expertise, GKN has spent the past year working with Saab to develop 3D-printed parts using metal powder bed technology, as well as ensuring that parts can be certified for use in aerospace. The partnership thus saw the successful delivery and certification of those parts, which are now flying on Saab aircraft.
Metal parts made via powder bed fusion at GKN’s facility in Filton, UK. (Image courtesy of GKN.)
“We are continuing that partnership and developing more opportunities for how we apply the technology to Saab products, working with them to get those products onto aircraft and get them flying through certification,” Sharman explained. Together, Saab and GKN will extend that partnership, ramping up industrial capabilities, using new materials and designs as a means of cutting production lead times and costs.
New AM Technology with ORNL
GKN also announced at the Paris Air Show that it had signed a five-year $17.8 million cooperative research and development agreement with Oak Ridge National Laboratory (ORNL) to research metal AM technology. ORNL’s Manufacturing Demonstration Facility will be utilized to develop a directed energy deposition (DED) process and to refine electron beam melting (EBM) for mass production.
“We’re already in production and have our own in-house laser metal deposition capability out of our engines business, which deposits features on engine structures,” Sharman explained. “We took that capability and we’re now working with ORNL to take that process and develop it for printing large aerospace structures.”
As a DED process, the laser metal deposition with wire (LMD-w) will use a laser to melt metal wire into beads onto a substrate. With ORNL, GKN will develop a prototype for creating complex medium- and large-scale titanium aircraft structures, including ribs, spars, bulkheads and frames. The company believes that it will be possible to cut material waste by 90 percent, while reducing manufacturing times by 50 percent.
“Laser wire deposition is one of those processes that we believe is scalable for larger structures,” Sharman said. “We’re looking at producing near-netshape parts to reduce waste and reduce the cost of large machined parts for aero structures. The longer-term goal is to then optimize weight savings and the longevity of the part.”
GKN’s laser wire deposition system. (Image courtesy of GKN.)
Whereas DED processes will be typically be used to produce large-scale parts, such as structural components, powder bed fusion processes are more likely implemented for a series of small parts or medium-scale components.
GKN’s Centre of Excellence in Bristol focuses on both laser powder bed and EBM 3D printing, determining which process is suitable for which applications. As a part of the ORNL partnership, GKN will be looking to produce complex small- to medium-sized components at high volumes.
Flying the Optical Ice Detector
As a developer of electro thermal ice protection systems (IPS), which are designed to keep ice from forming on aircraft, GKN created its patented Optical Ice Detector (OID). Necessary for the project was a titanium housing, which was 3D printed by GKN with its powder bed expertise.
The OID relies on a small sensor head made up of optical fibers that project laser light onto any ice that forms on the device. The OID can be attached to any surface of an aircraft or internal area of gas turbine engines where ice might accumulate. The OID allows for more precise control over an aircraft’s IPS by implementing the IPS system only where ice forms, instead of throughout the entire IPS system.
The OID system, attached to a research aircraft. (Image courtesy of the Facility for Airborne Atmospheric Measurements.)
GKN announced at the Paris Air Show that the company successfully flew the OID on a research aircraft, detecting real-world ice accumulation events and matching device performance in the company’s Icing Research Tunnel in the UK. In addition to detecting the ice itself, the OID measured its thickness and rate of accumulation.
For this product, AM was used for its ability to provide a quick turnaround, rather than create complex structures, according to Sharman. “In that particular case, it was all about the timing,” Sharman said. “We had a window of opportunity in which to fly that demonstrator on the research aircraft, and that window was very short. AM had a lead-time advantage compared to the other processes, and we were able to get the final part in a way that traditional manufacturing technology just couldn’t.”
3D Printing Rocket Nozzles
GKN also used 3D printing to produce the Ariane 6 nozzle for Airbus Safran Launchers for the Vulcain 2.1 rocket engine. Through the European Space Agency’s (ESA) Ariane Research and Technology Accompaniment Program, GKN leveraged laser welding and laser metal deposition to produce the massive nozzle, measuring 2.5 m in diameter. GKN will supply five subsystems for each Ariane 6 rocket that Airbus Safran Launchers aims to manufacture, including four turbine assembles for the two Ariane 6 engines.
Sharman pointed out that GKN has been a part of the Ariane program for some time. In fact, GKN has participated in the program since it began in 1974, producing more than 1,000 combustion chambers and nozzles, in addition to more than 250 turbines, for Ariane rockets since its inception.
“GKN supplied the Ariane 5 nozzles, and now we have supplied the Ariane 6 nozzle to ESA and Airbus Safran Launchers,” Sharman explained. “We used laser deposition on the nozzle product, which is a highly complex nickel super alloy product.”
The Vulcain 2.1 rocket nozzle, which reduced the part count from about 1,000 to just 100. (Image courtesy of GKN.)
GKN’s laser wire process saw the deposition of more than 50 kg of material used to reinforce the structure of the nozzle, as well as join parts. By using AM to produce key structural features of the nozzle, the company could reduce the part count on the nozzle from about 1,000 to just 100 parts, ultimately resulting in a 90 percent drop in part count, 40 percent reduction in costs and 30 percent reduction in production time.
The challenge for producing the nozzle was adapting the technology to a new material, according to Sharman. “Obviously, on a large rocket, that is a big engineering challenge,” Sharman said. “The process used was our laser wire process that we’ve got in house. The challenge was developing it for a different material, a nickel alloy in this instance. AM is a multiparametric process, which is kind of its curse. There is a large matrix of different variables. Whichever process you have focuses on understanding each of those variables and how they affect the thermal flow and energy input. It’s about tailoring that for the material to get the material properties you require for each geometry.”
The nozzle has already been successfully tested and will now be mounted to the Vulcain 2.1 engine for further testing. As Airbus Safran Launchers preps for the launch of the Ariane 6 rocket in 2020, GKN aims to manufacture the nozzle using a “highly automated” manufacturing center in Trollhättan, Sweden, which is set to open in 2018.
In 2012, Airbus published a video detailing its plans to 3D print an entire aircraft by the year 2050. As fantastical as that vision was, we’ve seen tremendous progress toward that goal in just five years—not just from Airbus, but from its suppliers, like GKN.
From establishing five AM centers in 2013 to the Paris Air Show in 2017, GKN has already produced numerous parts that will see 3D printing move from the Earth to the skies and beyond. To learn more, visit the GKN additive manufacturing website.