Additive manufacturing (AM), which involves constructing solid objects by adding layer upon layer of material, has been a dream in the aerospace industry for decades. To date, AM – also known as 3D printing – has been used mostly to create quick-turn prototypes of parts for evaluation and testing. But using AM parts in full production, especially for airplanes that will fly thousands of people per day, has not yet come to fruition in the safety-conscious industry.
That paradigm appears poised to shift, however. Airlines and third-party maintenance, repair and overhaul (MRO) companies, for instance, would like to fabricate their own spare parts and components as needed, instead of relying on the original equipment manufacturers (OEMs) that design and build their aircraft. Many MRO services providers, therefore, have latched onto AM’s potential and started applying additive manufacturing to the aftermarket, especially for parts that do not impact safety.
Emirates Engineering, for example, the Dubai-based technical arm of Emirates Airlines, partnered with 3D Systems, a leading AM equipment provider, to produce a video monitor shroud and air vent for use in cabin interiors. Such small inroads, experts say, could open the door to wider applications of 3D printing for aerospace parts.
"You’ll see 3D printing begin to transform manufacturing across aerospace due to the freedom of design it will enable.”Klaus Mueller
“More broadly, the industry could additively manufacture at least 30% of the components now flying on commercial aircraft, up from about 1% to 1.5% now,” said Klaus Mueller, senior advisor to Aerodynamic Advisory, a consulting firm specializing in aviation and aerospace strategy. Mueller also serves as a senior consultant for Bionic Production AG and Fraunhofer IAPT, two of Germany’s leading additive manufacturing institutes.
Using new technology cautiously
By necessity, commercial aerospace is a cautious industry, where new technologies are adopted only after exhaustive testing; priority number one is helping its airline customers keep air travelers safe.
While companies have successfully 3D-printed non-flight-critical components, volumes are relatively small. As a result, 3D printing remains in its early stages across the airframe and engine supply chain, said John Schmidt, who leads Accenture’s global Aerospace and Defense consulting practice.
Bell Helicopter, which has been employing additive manufacturing to produce parts since 2006, can attest firsthand to both the potential and the limits of 3D printing. The company uses AM to make about 200 parts, mostly with laser-sintered nylon.
“The team has really advanced Bell’s additive manufacturing applications, but we’re still a ways out from mass production,” said Justin Rivera, engineering specialist for Bell Helicopter’s Manufacturing Technology department. “The irony is that aerospace is where scientists and engineers routinely push the technology envelope,” Accenture’s Schmidt said.
Hurdles to overcome
A combination of regulatory, technical, cultural and economic issues lies at the heart of AM’s limited progress to date in aerospace.
For all its unique capabilities, 3D printing must perform like any other manufacturing technology. For one, it must be cost effective, and additive manufacturing generally isn’t yet ready to mass-produce components affordably, Mueller said.
“It comes down to raw economics,” Schmidt said. “It only becomes attractive if the weight reduction or the ability to produce a complex part that otherwise couldn’t be fabricated any other way can be shown to improve the total cost of ownership.”
That’s especially true when factoring in the time and cost of having to recertify a 3D-printed component to ensure it meets the same quality-control standards as the conventionally manufactured part it is intended to replace.
Complicating matters is that the industry has developed very few quality and reliability standards for 3D-printed parts, said Scott Killian, business development manager, Aerospace, for EOS, which supplies metal and polymer laser-sintering AM machines, materials and services. Glenn McDonald, a principal at AeroDynamic Advisory, also notes that certification of components by the Federal Aviation Administration (FAA) can still take up to two years.
“The process is long and arduous,” said Tom Kurfess, chief manufacturing officer at Oak Ridge National Laboratory (ORNL), a federally funded research and development facility that is working closely with multiple industries to perfect AM. “Manufacturers must be able to certify 3D-printed parts based on a repeatable process that can consistently and reliably yield the quality ] that designers expect at a cost that makes 3D printing the clear choice over other processes. That’s the holy grail,” he said.
The challenge, Kurfess said, is that consistently producing reliable parts is an ongoing difficulty for AM. Using the same settings, for example, can lead to differences in producing the same part. The list of factors that can impact the quality of a final part is lengthy and includes, among other things, part orientation with the build platform, machine calibration, material quality and how parts are removed from a build.
“All of the process variables must be strictly defined and controlled to enable a successful print each and every time, which is no small feat,” Kurfess said.
Another issue is that machines used for 3D printing generally don’t meet users’ expectations, said Laura Ely, a former leader of GKN Aerospace’s AM initiatives who is now an industry advisor at the Barnes Group, an engineered products manufacturer. “If you buy a standard CNC (computer numerical control) machine, you expect it will require very little tweaking,” she said. “That’s not the case with today’s 3D printing machinery, which tends to require extensive adjustments due to their current level of maturity.”
A closely related challenge is the insufficient number of education programs to qualify more AM machine operators. Broad estimates of the number of available operators range from fewer than 1,000 to around 3,000. Much of the discrepancy can be traced to how a fully qualified AM operator is defined, since AM involves multiple disciplines.
What professional manufacturing trade groups can agree upon is that there’s a critical shortage of 3D printing skills, and the rate at which new operators are entering the field is unlikely to keep pace with demand for the foreseeable future. Manufacturers are struggling to find the skilled workers needed, despite an increase in industry and government-sponsored training programs, according to many organizations that include Society of Manufacturing Engineers and the US Chamber of Commerce.
In Europe, the Sector Skills Strategy in Additive Manufacturing (SAM) consortium recently completed a study on AM workforce training and discovered a critical shortfall. SAM’s goal is to gather the information needed to rapidly expand tailored training programs. Then there is the pressing need to train product designers to think in terms of using additive manufacturing when they conceptualize products, to ensure that they can be made and certified as airworthy
Given the hurdles, it would be easy to conclude that AM’s future in aerospace production manufacturing is not as bright as once thought. Not so, experts say.
The launch of next-generation commercial aircraft programs by Airbus and Boeing is widely expected to put AM on a steep growth curve, although the two rivals are unlikely to make those multibillion-dollar investments until the mid- to late 2020s, Accenture’s Schmidt said. The reason? The global pandemic decimated passenger traffic, forcing cash-starved airlines to postpone their fleet-modernization plans.
Before OEMs announce their plans to introduce next-generation aircraft and put them into production, air travel demand will need to recover. That is not a question of if, but when – at which point the opportunities for commercial aviation equipment suppliers to exploit 3D printing will multiply many times over, industry players agree.
The benefits of AM remain clear, along with its potential to support commercial aerospace manufacturing on a large scale, as it’s now doing in the space and automotive industries, Mueller said.
For example, additive manufacturing is moving quickly to meet even greater requirements including complete, 3D-printed combustion chambers with high-performance features, lighter weight structural components and even fully 3D-printed satellites.
“3D printing allows innovative solutions by reducing part count and production costs found with conventionally manufactured components.”Justin Rivera
“While still in its infancy for global acceptance and certification on in-service aircraft, 3D printing allows innovative solutions by reducing part count and production costs found with conventionally manufactured components,” Bell Helicopter’s Rivera said.
AM also continues to mark new milestones through persistent innovation, including flame-retardant vents, camera mounts and housings for the Mars Rover test vehicles. As additive manufacturing continues to evolve, manufacturers and government regulators are collaborating to address AM’s biggest challenges.
“What everyone needs to understand is that 3D printing is under-exploited across aerospace and has lots of room for growth,” Schmidt said. “The unveiling of next-generation platforms by OEMs is when AM will really take off.”
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