With in-situ consolidation, part makers can form a unified composite structure comprising several different components in real time. This eliminates the need to drill holes to bolt things together. “You don’t want to drill holes in a composite part if you can help it, because you’re breaking the fibers,” Melilli says.
In-situ consolidation also enables the manufacture of strong, lightweight parts in less time. “Thermoplastics can be put down substantially faster, and there’s not as much waste,” says John Tyson, president of Trilion Quality Systems. The graphite epoxies used for thermosets have a limited shelf life, and they can become outdated before manufacturers can use them. With thermoplastics, there are no shelf life limitations.
Thermoplastics offer another advantage. “Thermoplastic parts are effectively just as strong if not stronger than thermosets, because they don’t have as many knockdowns,” Tyson adds. “You don’t have to put additional material on the part, which makes it lighter.” He notes that thermoplastics are already being used in aircraft like the Airbus A380, which has a thermoplastic leading edge. In addition, Tyson predicts that the use of thermoplastics could reduce costs substantially, perhaps as much as 50 percent.
While the work being done in thermoplastics holds promise, Melilli cautions that it’s not yet ready for large-scale production. “Where and how thermoplastics will have a role in increasing the production throughput of aircraft is still developing,” he says. “There’s a lot of interest and work by major companies in this area. The materials manufacturers, the Tier 1s and the OEMS are working together to explore how and where these kinds of technologies will fit well with certain classes of their parts.”
In-Situ Inspection and Repair
One of the challenges in moving to OoA parts production is maintaining the quality. “When you put the thermoplastic in a tool and then you put the tool in an autoclave, the annealing or curing process under a vacuum bag and against a hard tool solves a lot of problems. A lot of errors in manufacturing are fixed in the curing process,” Tyson says.
GA-ASI, for example, has begun incorporating in-situ inspections along with in-situ rework and repair into its tool-less manufacturing process. This makes the process more reliable and efficient and yields more predictable results.
ARAMIS Thermography, developed by Trilion Quality Systems, is a full-field optical measurement system that can monitor the quality of composites parts as they’re being produced. It’s an integral part of the Real-time Virtual Assembly Tooling (RVAT) system being used by GA-ASI.