Fastems’ automated laser-ablation cells increase efficiency and quality in F-35 lightning II wing assembly.
In December of 2020 Fastems announced an agreement for the delivery of two automated structure laser ablation (Auto-SLC) robot cells to Lockheed Martin’s Fort Wort site. The cells are used in the F-35 Lightning II wing assembly line. As the delivery was completed in early 2022, now it’s time to take a deeper dive in to the idea behind the cells and to have a look into the installation process at the site.
To summarize, three key achievements of the project include:
- Ablation time reduced to half.
- Quality controlled ablation process means less disbonds.
- Overall process stability and quality increased.
The ‘What?’ and ‘Why?’ of Auto-SLC cells
F-35 fighter jet wings are comprised of a metallic understructure with carbon-fiber panels, making them lightweight and extremely difficult for radar to detect. The outer panels are fastened to the wing structure using bolts and bonded nutplates. To ensure the wing assembly meets performance requirements, the bonding interface between the nutplate and the structure must be completely clean from any surface treatments, topcoats, dust, or other FOD. To get an idea about the scope, each wing frame of a F-35 has around 1500 holes that require ablation. The Auto-SLC uses a laser to ablate the surface around the holes where nutplates are bonded, removing any surface impurities which may contaminate the bonding surface. The system incorporates a dust-removal system that takes care of any evaporated impurities during the ablation process. The cells also feature an automated ionized water-flushing system for cleaning the wing of any potential FOD prior to the ablation process.
Ablation of the bonding surface is very important as it eliminates disbonds of the nutplate during the wing assembly process. Any disbonds during the manufacturing process require wing disassembly, nutplate retrieval, and reassembly of the wing. This can add up to a costly multi-day delay.
Previously the ablation process was performed manually using a handheld unit. This legacy system was cumbersome, limiting the amount of holes that could be ablated. Automation of the process has allowed for a smaller unit, therefore increasing the number of holes that can be ablated and reducing the overall time of the hole prep processes. More ablated holes also means reduced disbonds and further timesavings downstream. The Auto-SLC uses machine vision aided positioning for accuracy and smart quality control. Automation of the system cuts the ablation processing time in half.
Auto-SLC cells benefit from digital twins, which means that the real-life manufacturing cells have digital representative 3D-models that enable programming and testing in a safe environment and without production disturbance. When it comes to robot programming, the digital twin is not simply a nice feature, but rather an absolute must: teaching the exact location of thousands of holes is impossible to handle manually. Programming in the digital environment is also critical to change management, allowing for automatic and instantaneous updates to be saved and tracked throughout the process.
Thanks to machine vision solutions from the Finnish supplier Roima, the ablation process can position itself with a tolerance of +/ 0.01 mm. This is achieved by fine adjusting the laser beam with the help of the machine vision. The combination of robot accuracy and machine vision adjustments is critical to ensuring the system meets its technical requirements while operating within its environmental and budget constraints.
The internal structure of the wing is very narrow and labyrinth-like, creating a challenge for the system to ensure reach its target number of holes while avoiding contact with the part. In the most difficult spots, the laser head is only millimeters away from the wing body. To achieve maximum accessibility, several hundred hours were spent on the 3D-simulation to design the laser end-effector’s positions and to determine the robot’s movements. The laser equipped end-effector used in Auto-SLC’s is truly unique in this sense.
Featuring so many novel technologies, the project has given Fastems much more experience on laser, machine vision and advanced robotics. Also, the integration capabilities of the company have risen thanks to the satisfactory cooperation with Roima and Ionix who designed the laser ablation end-effector.
“Partnership with Roima and Ionix was one of the key elements in successful developing of this project. Combining Fastems’ leading aerospace automation experience with both partners’ competence on their fields is what enabled us to deliver a cutting-edge application to a world-class customer,” says Mika Laitinen, Fastems’ Sales Director of Robotic solutions.
Fastems and Lockheed Martin share many years of history. The story of the Auto-SLC cells began in AeroDef 2017 where Jeff Langevin, Assembly Automation Lead – Manufacturing Technology at Lockheed Martin Texas Fort Worth met with Risto Niemi who is Fastems’ Solution Sales Director. At the conference, the use of laser in F-35 production was brought up and the discussion went on to the possibilities of automating its use.
“Jeff and his team had a clear vision and defined needs as well as deep understanding what technical points should be physically tested before the actual go-live in production. Based their list of expectations, Fastems could easily start the conceptualization work.” Says Niemi and concludes “This level of projects is only possible when both parties know each other’s expectations and capabilities.”
Naturally, Fastems’ hopes that this Auto-SLC delivery is not the last of its kind. Both parties see more utilization of the technology throughout the factory and beyond. After all, the F-35 fighter has a total of more than 30,000 holes, which could be automatically cleaned with this type of equipment. What comes to the results so far, Mr. Langevin explains:
“Fastems has been an excellent teammate in helping us achieve our affordability goals in F-35 production. Their attention to detail in engineering of the Auto-SLC’s laser ablation components and the seamless integration of the system into our wing production line has been critical at reducing span time, on time.”
Final acceptance completed in March 2022
The final site acceptance was completed in March of 2022. As the cells were integrated into an existing and constantly working production line, the installation project required an extra amount of cooperation and planning. The installation process is illustrated using pictures, gathered by Lockheed Martin and Fastems’ project Manager Aleksi Mäkäräinen, who concludes: “This project is an excellent example of what can happen when top-notch tech companies cooperate for innovative solutions”
Check the following video-story to see how the installation at the site was carried out!