“This technology uses a high-speed, thermographic camera. We can heat up a cured part, and as the part cools, using that camera, we can actually detect any voids or any foreign objects that are in the part,” Melilli says. “That allows us to know whether or not the part is acceptable from a quality standpoint. It’s faster than using ultrasonic technologies, which are the current accepted standards for examining parts after they’ve been made.”
One camera can do a lot of different things, Tyson explains. “While we’re laying tape down with a robot head, we can track that head in six degrees of freedom so we can make sure that it’s laying down material where it’s supposed to be,” he says. “We can check the bond quality of the material that’s getting laid down and we can check the shape of the material – or the whole part – while it’s being built to make sure it matches CAD in real time.”
Tyson says the number of production steps for in-situ monitoring with thermoplastics is half the number required for thermoset parts production. This makes manufacturing up to 10 times faster and may cut costs in half. But utilizing data from thermographic cameras could be helpful in thermoset parts production as well. The cameras could immediately detect any foreign materials caught between the layers of fabric during the lay-up process.
To take advantage of the cameras’ capabilities, Trilion has begun adding patterns on critical composite parts during manufacturing to enhance visual inspection. Using data from thermographic cameras, aircraft companies will be able to look for changes in the pattern to check for strains on those parts. They can monitor a plane’s structural health during its lifetime without adding any weight or power (such as multiple strain gauges or acoustic sensors) to the aircraft. It is equivalent to using millions of strain gauges, according to Trilion.
The use of sophisticated software is another way that manufacturers can speed parts production while improving the parts’ quality. Fiber patch placement, for example, could cut lay-up time for tools and reduce the amount of fiber required for a composite part without impacting its strength.
Developed by Cevotec, the fiber patch placement process uses pieces of unidirectional material, ranging from credit-card to letter-sized, in conjunction with a flexible gripper and a CAD model. After the gripper picks a patch up, a camera in the system exams the material for defects. The gripper then places each patch on a tool, arranging and orienting the pieces to optimize the strength of the part along its load path.
“We have the potential of arranging the patches so that they are precisely where they need to be in the part to provide the strength that the part needs as defined in its CAD model,” Melilli explains. “The software does all of the analysis, including a finite element analysis of the part.”
With this system, companies could produce thermoset or dry fiber preforms that can either go into an autoclave or into a clamshell mold for resin infusion. Plus, fiber patch placement is a faster process than hand lay-up, eliminating many steps in the manufacturing process.