Additive manufacturing (AM) or 3D printing has moved well beyond prototyping. Today, most aerospace companies use it to improve the functionality of existing components and fabricate non-structural parts for commercial and general aviation aircraft.
AM enthusiasts envision the day when this revolutionary process will be used to “print” entire fuselages, wings and critical engine parts with complex geometries, including embedded sensors and other electronics. To achieve that disruptive vision, however, AM needs to overcome some difficult hurdles, according to Oak Ridge National Laboratory (ORNL), a US Department of Energy research facility in Tennessee. ORNL is collaborating with hundreds of companies across multiple industries to advance AM.
“In some applications, such as rapid prototyping or specific medical devices, where many parts have been printed, additive manufacturing is pretty mature, but for most applications it’s embryonic,” said Bill Peter, director of the US Department of Energy’s Manufacturing Demonstration Facility at ORNL.
QUALITY ASSURANCE WITH 3D PRINTING
Each year, ORNL hosts more than 5,000 visitors representing about 700 organizations who want to discuss, among other technologies, additive manufacturing. Those visitors make clear, Peter said, that one of AM’s biggest hurdles is to achieve quality levels that instill as much confidence in AM-produced parts as in those made with traditional processes, including parts that are critical to the end product’s performance and safety.
“Their biggest concern is that there is no methodology for establishing the integrity of additively manufactured components,” he said.
“IN SOME APPLICATIONS,SUCH AS RAPID PROTOTYPING OR SPECIFIC MEDICAL DEVICES, ADDITIVE MANUFACTURING IS PRETTY MATURE, BUT FOR MOST APPLICATIONS IT’S EMBRYONIC.”BILL PETER
DIRECTOR, OAK RIDGE NATIONAL LABORATORY
Small modifications in process parameters and the resulting microstructures of the deposited material, such as powdered titanium or nickel, can drastically change how the end product behaves, Peter noted.
“Long term,” he added, “we’ll use a framework of data analytics and visualization systems to show how to repeatedly build a complex part with the level of quality that aerospace manufacturers require, but we are still a few years from reaching a full solution.”
ADDITIVE MANUFACTURING'S NEED FOR SPEED
Another hurdle is the speed at which the raw material used to print a part can be deposited.
The AM process starts with a computer- generated, three-dimensional part design. The file is downloaded to the additive machine’s computer and electronically sliced into extremely thin layers. The machine spreads a thin, even layer of metal onto the build plate. A computer-controlled laser or other energy source, following a path that corresponds to the sliced data of the original 3D design, sinters or melts this thin layer of metal. The layering process is repeated until the part is rendered, but the process can take more time than traditional manufacturing techniques.
That’s a problem, because manufacturers are continually looking for ways to reduce production cycle times. “Improvements in deposition rates will increase the viability for applications of additively manufactured components in aerospace and other industries,” Peter said.
Based on progress in just the past two years, however, researchers are encouraged. For example, ORNL collaborated with Cincinnati Incorporated, a US-based build-to-order machine tool manufacturer, to develop a highly innovative AM system able to print reinforced polymer components up to 10 times larger than today’s machines, up to 1,000 times faster, with a deposition rate of 16,000 cubic centimeters per hour, compared to the 16 to 65 cubic centimeters per hour more typical of AM machines historically on the market. Applying knowledge gained from working with polymers, Peter said, the team is now focused is on achieving similar improvements in deposition rates using powdered metals.
COMPOSITES' JOURNEY PARALLELS AM'S
Kevin Michaels is a vice president with ICF International’s aerospace and MRO consulting practice and a globally recognized authority on aerospace manufacturing. As AM continues to evolve, Michaels said, the industry should draw lessons from its experiences with other transformative technologies, especially composites.
“THE PACE OF INNOVATION AS A WHOLE IS GETTING MUCH FASTER, PRIMARILY BECAUSE ESTABLISHED PLAYERS HAVE REALIZED THE DANGERS OF NOT MOVING FAST ENOUGH.”ANTOINE GELAIN
AEROSPACE INDUSTRY PRACTICE LEADER, CANDESIC
In the 1970s, composites were widely touted for their strength and corrosion resistance but took decades to perfect. Few foresaw the day when entire fuselages would be built from composites, as they are now.
“The future of additive manufacturing will bring similar surprises that may look logical in hindsight but are hard to envision today,” Michaels said.
The comparison of composites’ development to that of additive manufacturing is instructive, said Antoine Gelain, managing director of London-based independent private equity firm Paragon European Partners and aerospace industry practice leader at Candesic, a London-based strategy and management consulting firm.
“The analogy tells us there is a huge gap between a technology’s applicability and marketability, and it takes years if not decades to close that gap,” he said.
Like AM, composites had to earn manufacturers’ trust. “While composites’ applicability to aircraft structures was established early on, its disruptive nature in terms of certification and manufacturing processes meant that it took a long time to convince customers to switch and to make the business model of composite manufacturing viable,” Gelain said. “However, additive manufacturing is likely to go much faster, because transformational technologies can be more easily adapted in the digital age.”
In the end, he said, business challenges will drive advancements in AM.
“The pace of innovation as a whole is getting much faster, primarily because established players have realized the dangers of not moving fast enough, and so they are willing to take more risks and invest more money in disruptive technologies than they used to.”
Watch the creation of the world’s largest AM part: http://3ds.one/3DPrintBig