The is being delivered, the is taking shape, the and are to be reengined, and 's is in the early stages of a 20-year production run. These aircraft will dominate manufacturing for the next decade, and they are no longer malleable concepts.
Material-system choices and structural-design decisions have been made; the balance between metals and composites is settled for the next decade. So where could advances in manufacturing technologies come into play, with so much decided already?
The answer is in pushing production rates higher and costs lower. Manufacturers see plenty of room for improvement, even with the big materials and structures decisions already made. “There is enormous opportunity to implement technologies to reduce cost even after the aircraft is mature, as we did over with theover the years,” says Don Kinard, Lockheed deputy director and technical lead for the F-35 production system.
So development of manufacturing technology is continuing apace, even if the battle between composites and metallics has cooled now that Airbus andhave put off their next-generation single-aisle airliners to the late 2020s. There are opportunities for advanced materials and manufacturing technologies, but they are different for each platform. “There will one level of technology enhancement on the A320NEO/737 MAX, a different set on the A350/787 and another on the ,” says Rich Oldfield, technical director for aerospace at aerostructures supplier GKN.
“At an architecture level, in many cases the technology standard is set—we will not see a carbon wing on the NEO or MAX,” he says. “Instead, where we will go is production enhancements; new technology being applied, not at a fundamental level, but around the edges of the architecture. Over the next decade, we see opportunities that demand different sets of technologies based on the primes, architectures and rates.”
In the high-volume narrowbody market, following the dramatic shift to composites in the widebody Boeing 787, industry had been bracing for an all-out battle between carbon-fiber and advanced aluminum-lithium alloys for dominance on clean-sheet designs. But the decision to reengine existing single-aisles has delayed any showdown.
Opportunities to change materials on the NEO and MAX will be limited. “Probably quite a lot of the architecture and technology standard will remain the same,” says Oldfield. “With the requirement to minimize change, the focus is on the engine-to-wing integration, pylon and nacelle—only where needed for the new engines.”
If changes to the A320 and 737 are constrained, there is more opportunity on the A350 and 787, still early in their lives with much development work ahead, particularly on the larger A350-1000 and 787-10. “We could see some fundamental shifts on the A350-1000 and an opportunity to apply technologies quite significantly all around the architecture, on both the airframe and the engines,” Oldfield says. Still in definition, the 777X could see more fundamental changes, including a carbon-fiber wing.
The bigger the change, the harder it is to make, but below the level of fundamental materials and structures choices there are ways to improve manufacturing processes and reduce airframe weight and production cost. “With a platform at the start of its manufacturing process, and not down the maturity curve, there is tons of work that can be done for cost and weight reduction,” says Oldfield. “We are nowhere near rate on the A350, and there is a lot of machine development and process improvement we can do.”
With the F-35 still in development, Lockheed is focusing on manufacturing improvements that can be made while minimizing engineering changes. “There is potential where a process is highly manual, such as fitting fasteners, or involves a lot of drawing interaction,” says Kinard. “To change a skin would be extremely difficult and expensive. We would have to redo and recertify the design, and possibly do aircraft testing. At this point in the program, that is not likely,” he says. “Block changes in the future will require structural changes, and we will have an opportunity then.”
Leading the list are operations with high touch-labor or quality problems. “We spend a lot of time putting fasteners in the aircraft—all different sizes and types—looking at drawings, marking up skins and putting them in,” he says. “We are implementing optical projection, projecting the information onto the skin.” The laser technology, already used to position composite plies during hand layup, is mature. Others are less so.
“Augmented reality is still fairly out there but has huge potential, so we are doing pilot programs to bring three-dimensional engineering data to the mechanic level,” Kinard says “Today, they use two-dimensional drawings, but the engineering is done in 3D. So we are working on turning engineering models into 3D drawings and taking iPads and iPhones and trying to understand how to use them [on the factory floor].”
In composites, automation is key. Carbon fiber provides the performance improvement required, but volumes must be increased and costs reduced as the 787, A350 and F-35 move into rate production. As the industry shifts from manual to automated layup, the speed with which carbon fiber can be deposited on mold tools has become the key driver.
“Deposition rate is critical, as it defines the capital assets required,” says Oldfield. GKN is producing rear wing spars with integrated trailing-edge ribs for the A350. “There is a half-ton of material per spar, and we will produce 13 a month at rate for the A350. That's a huge value of carbon, so deposition rates have to be high,” he says. Rates are not where they need to be, requiring advances in materials, tools, processing and inspection.
There are several levels of automation. Pick-and-place is hand layup using a robot to position the plies. Automated tapelaying allows flat or gently curved parts to be laid up at high speed, but more-complex components require slower automated fiber placement (AFP). Each demands a specialized and expensive machine, but that is changing. “You're beginning to see combinations of tape-laying and fiber-placement, and also pick-and-place, so you don't have to lay up huge parts with AFP when it's only needed on a small place,” says Oldfield. “With the National Composite Center in Bristol, [England], we are looking at multi-head robots that use different technologies on the same part at the same time.”
“In the past, you had an automated tape-laying machine and if you wanted to do another operation, you had to stop the automation and get into the tool to place a fabric ply or metal mesh by hand. With a modular-head machine, you can keep the automation going and have the flexibility and adaptability to use it on a variety of platforms,” says Clint Church, aerostructures chief engineer at Aurora Flight Sciences, which supplies airframe sections for theand CH-53K.
As with automated drilling, sufficient volume is essential to justify the investment. “We are building so many aircraft, we can use a lot more automation,” says Kinard. “We auto-drill and countersink over 90% of the holes in the exterior of the F-35. Robotic spraying is limited on legacy aircraft, but we have to very precisely control the thickness of coatings and could not do it any other way.”
Because of the need to tightly control the stealth fighter's outer mold line, Lockheed is looking to automate inspection. “Measuring steps and gaps, the flushness of fasteners, is so manual,” Kinard says. The company is using structured light—projecting a pattern onto a part so a vision system can measure its shape and compare it with the 3D solid model. “We save the data as we measure it, which gives us a record,” he says.
The implications of automation for the supply chain are growing as composites gain ground against metals. “Composites are not new, but the 787 and A350 are converting the baseline for future platforms,” says Church. “Composites are being held up as the high-end solution, and those that follow will adopt them where it merits or not.” With composites established in the commercial-airliner and general-aviation markets, he expects regional and business aircraft to follow.
The build-to-print tradition that established a broad and competitive metal-structures supply base is challenged by the different nature of composites. To take full advantage of the stiffness, strength-to-weight, corrosion and fatigue properties of composites, they need to be designed into platforms earlier, says Church. “You can merge features into one component to save weight and assembly time, make it as one big piece rather than bolting it together, but you have to do it up front to make sure the loads go certain ways.”
This should favor suppliers with design/build capability. “A metal solution is a more mature technology. You can get someone out of college who understands it and can design in it. It's a bit different with composites,” says Church. In addition to producing the CH-53K main rotor pylon, Aurora is Sikorsky's airframe supplier-partner for the S-97 Raider high-speed helicopter. “Aurora is a mini-prime for whole vehicles and understands system engineering. We have a foot in the door of both prototyping and production. That helps us be a better design/build supplier,” Church says.
In metallic structures, higher-tier players have their own supply chains making parts. But Oldfield does not believe the composites supply chain will be as deep. “The composites value chain is short,” he says. “The supply chain is the materials supplier and the machine supplier—there's no one else. GKN is turning raw material into product, and on the A350 and 787, we can do the work within our own walls and not offload at all.”
But competition within the supply chain brings down costs, and primes want to see the composites industrial base expand. For those companies that want to become suppliers, the capital cost of autoclaves and automation can be a barrier to entry. “The cost of composites is an inhibitor to growth, and automation is the key to driving cost down, but you need enough pounds per year to justify the machines,” says Church. “Clearly, 787-sized programs do that, but how many others will?”
Out-of-autoclave (OOA) composites cured in ovens under vacuum-bag pressure are seen as a way to produce large parts, avoid autoclave costs and broaden the supply base. “GKN has development programs in both, and always does a trade, but in most cases the cost benefit of out-of-autoclave is completely outweighed by the performance of the part in the aircraft,” says Oldfield.
OOA has been held back by lower mechanical properties than autoclave composites, but newer materials perform at a similar level, allowing use in primary structures, says Carmelo Lo Faro, vice president of technology for composites supplier Cytec.is using an OOA prepreg material system from Cytec for the 85 fuselage. “I think it is niche process for producing very large structures that would otherwise need a large autoclave,” says Church. “The processing time is not all that different and the cost of operating an autoclave versus an oven is in the margin.”
Australia's Quickstep has developed a way of curing parts in closed tools using heated and pressurized fluid but has started by making conventional autoclave parts for Lockheed while it works to qualify its process for the F-35. Savings up to 30% are projected, “but we have to show it works, then design for it, which is where you get all the benefits,” says CEO Philippe Odouard.
For a new process, qualification is an arduous undertaking. Lockheed is helping Chicago-based Sciaky qualify electron-beam direct manufacturing for the F-35. This promises to reduce lead times and material buy-to-fly ratios for complex titanium parts that are now forged by building them layer by layer instead. The initial component targeted is a flaperon spar, says sales manager, Bob Salo, but first Sciaky must gain process approval and part qualification.
“We could save a lot of money, but we have a long road to go. We have to validate the material, the process, then demonstrate structures—most of the applications are facture-critical,” says Kinard. “There is a lot of opportunity for additive manufacturing, but there is a lot of conservatism. It would be a lot easier if it had come along 10 years ago.” NOTE: Story has been modified to correct Sciaky's location.