Speed, leading edge technology, and cost-effectiveness characterize the Lockheed Martin F-35 Lightning II family of multirole combat aircraft. A long-range supersonic fighter, the F-35 can fly at Mach 1.6; has stealth capability to evade detection and enter contested airspace; and serves as an information and communications gateway to share its operational picture with allied ground, sea, and air assets. Production speed, state of the art technology, and affordability also characterize F-35 manufacturing operations. Development and production follow a digital thread concept stretching from design through manufacturing to ongoing support. Digital data, 3D solid models, and continual internal communication guide factory automation, manufacturing, and sustainment efforts while maximizing economy of operation.
Lockheed Martin, the prime contractor for the F-35, works with a global supply chain of more than 1,900 companies based in the United States and in 13 nations acquiring the aircraft. The aircraft’s forward fuselage and wings are built at Lockheed’s facility in Fort Worth, Texas. Evolution of the machining operations for the aircraft’s cockpit-area forward fuselage understructure demonstrates Lockheed Martin’s commitment to continuous manufacturing improvement.
In 2006, about five years after the first F-35s were produced, a multi-day Kaizen event examined the overall manufacturing process looking for improvements. Manufacturing Technology Fabrication Lead Jeff Langevin says the Kaizen sessions showed transportation and ergonomics issues of readying the fuselage for machining and drilling operations weren’t value-adding activities. “Moving airplane parts around a factory and transferring NC programs are interface tasks that don’t necessarily build airplanes, but they impact our ability to do so efficiently,” he says.
The original process used an overhead monorail system to pick up and move the fuselage to different machine tools. Each move required a crane operator plus personnel on the shop floor to rig the fuselage, rope off areas, and shut down sites under the lifting path to assure safety of floor personnel. Transporting the fuselage into and out of the machining locations required about 10 moves between machines, including working above and below the fuselage; setting up step stools, ladders, scaffolds, and platforms for technician access; as well as washing debris from the fuselage.
Integrated machine tool transfer line
Langevin’s team worked with factory automation systems provider Fastems to blend machining and transfer operations into an integrated machine tool transfer line (MTTL), using flexible manufacturing system (FMS) technology. On the MTTL, a fuselage section is lifted into a load, unload, and skin installation (LUSI) station. The LUSI station, also built by Fastems, allows a single worker to raise, lower, and spin the fuselage, allowing operators to stay at floor level while manipulating it to the positions necessary to perform operations. Before the Fastems line was installed, a move from the LUSI station to the wash station consumed hours and required participation by multiple personnel. Now the move takes two or three minutes and one worker pushes a button. The system reduces total process or span time cost and minimizes labor expense.
Next, an FMS stacker crane carries the section down the production line to a house-sized Parpas America precision milling machine (PMM) that mills and drills the understructure of the fuselage to accept the F-35’s composite skin. The MTTL then delivers the fuselage section to a Fastems-designed wash station where machining debris is rinsed off and the section dried. It’s then transferred to a LUSI station where side skins are attached. Next it goes to a Cincinnati Automated Drill & Trim from Fives Group that makes about 500 holes in each side of the structure. A tool preset booth monitors tool wear in real time and dictates preemptive tool changes to avoid process interruptions. The fuselage then returns to the wash station and finally to a LUSI station to be prepared for the next step in the manufacturing process, which occurs outside of the MTTL.
Brian Sykes, F-35 forward fuselage lead specialist, says, “The forward fuselage team works hand in hand with the automation system to reduce time, increase accuracy, and improve safety. We noticed a major reduction in hours per unit from 132 hours to 98 hours, which is a 34-hour, or 26%, reduction. The number of monorail moves decreased from 18 to 2, and the system also improved ergonomics for mechanics’ manual drilling operations. That’s the biggest benefit – a significant reduction in transportation time and movement.”
Increasing production capacity
Fastems and Lockheed designed the system to be modular and expanded as F-35 production increased. Phase 1, installed in 2011/2012, featured four LUSI stations, two PMMs, a wash station, one Auto-Drill, and the tool preset station. Six years later Lockheed added another Auto-Drill and LUSI station. A third expansion added another PMM while Fastems continually develops manufacturing management software (MMS) that plans, runs, and monitors production in the MTTL. Fastems worked with Lockheed’s technology group and workers on the line to assure integration is seamless, product quality remains top-notch, and there’s no downtime during system upgrades.
Langevin says, “The MTTL really shows our internal stakeholders and our customers that we’re committed to finding ways to make the F-35 affordable. We want to add value to the program that goes beyond just machining faster, drilling a hole faster, turning a wrench faster. This means finding the areas of waste between machining processes and making things easier and safer for our workers so they can do their jobs more efficiently and make the highest quality aircraft possible.”
“The Fastems system shows that there’s a place for flexible automation in an aircraft assembly line,” he continues. “We recognize we’re not an automaker, we’re not putting out a car a minute or whatever it is. That’s not our rate. But we can take the automation tools, those new technologies, and use them to reduce costs in ways that haven’t traditionally been associated with minimizing costs for aircraft manufacturing.”
As a result, the 75% reduction in span time provided through the MTTL enables Lockheed Martin to manufacture up to 20 forward fuselages a month.
“The Lockheed/Fastems relationship truly does feel like a team,” Langevin says. “Sometimes we forget that we’re a supplier and a customer because we’re working so closely together. We have a common goal to make things more efficient and that’s helped us take the transfer line to the next level and expand the system with minimal impact to our production.”
Langevin says the forward fuselage line has expanded as far as it physically can, literally reaching a wall at the north end of the facility. “We squeezed every square inch out of that thing that we possibly could,” he says. “However, because of the success of the MTTL, we did find a way to further optimize that area. Fastems suggested and helped us integrate buffer stations. When we couldn’t take the line any further north than where our factory ends, we were able to expand the line a little bit east with buffer stations that allow us to get more fuselages into the line at once so that we can take full advantage of all our machining centers.”
Next productivity steps
In hardware, the MTTL apparently has grown as far as possible, but Lockheed and Fastems continues developing the control software and other ways to further understand how the system is operating and to improve efficiency and output.
Lockheed is also working with Fastems in other areas of the manufacturing process. The aircraft plant is about to put into production an Automated Structure Laser Cleaner (Auto SLC) system supplied by Fastems for the F-35 wing line. The system uses a laser ablation scan head to automatically remove primers and other protective coatings from F-35 wing components. Auto SLC produces a pristine surface to which nutplates can be mechanically bonded without using attach rivets. The system eliminates manual sanding and solvent wiping that consumed significant time and yielded unbalanced results.
Part of the companies’ ongoing relationship is a Fastems-proposed agreement in which it provided on-site support for the first several months of operation to help Lockheed get the most out of its Fastems systems.
“They really are committed to giving Lockheed not just a piece of hardware but also something that’s going to help us take the next step,” Langevin says. “It’s been a great team effort between the two companies. I’m not surprised that it’s been so successful, and we look for ways to continue that effort in different areas of the company.”