Aerospace and automotive companies appreciate the strength and light weight of composite parts, but currently use them only in relatively limited ways. One reason is because composite part producers can’t currently deliver enough product at the speed and quantities required for large-scale production. But the increasing use of automation and robotics in composites manufacturing could remove those obstacles.
Composites manufacturers began experimenting with robotics for both thermoset and thermoplastic production about 30 years ago, with companies concentrating their efforts on automated tape laying (ATL) and automated fiber placement (AFP). Manufacturers gradually overcame the initial hurdles – the need to develop a targeted heat source for structure consolidation, software and materials suitable for testing – and today many use AFP and ATL to make parts. But limitations remain. The throughput rate is relatively slow, and AFP is restricted by the type and shape of structures it can produce.
The recent introduction of lasers as a heat source is helping to speed production, especially with thermoplastics, according to Ralph Marcario, vice president of sales and marketing for Automated Dynamics, a supplier of automation equipment. With laser heating systems, manufacturers can make products about four or five times faster without sacrificing any quality of consolidation, he says.
“In the automotive model, where generally there’s going to be some kind of secondary operation such as thermoforming or stamping and they don’t need to worry about consolidating on the fly, a laser heat source will enable extremely fast lay-up of preforms,” says Marcario. “That has garnered some particular interest lately from the automotive community, where high-volume production has historically ruled out AFP.”
But automotive and aerospace manufacturers are now most interested in automated inspection. “Although AFP has found more widespread use in production environments, one of the factors that limits its use is the need to still manually inspect the quality of the lay-up between every ply,” says Marcario.
Automated Dynamics is currently working with Flightware, a technology development company, to produce an automated inspection system. And according to Marcario, there’s an interesting difference between what they are doing and what others are doing. “Unlike other systems that would perform an inspection after a ply has been laid, our system would employ a sensor that’s mounted directly to the AFP head itself and would perform the inspection as the tape is being placed in real time,” says Marcario. “So ostensibly, in an ideal world, you would drive the down time for inspection down to zero.”
The system employs a sensor that dumps a data cloud into a computer program. “Most of the magic is with the computer taking these reams and reams of data and, in real time, being able to make sense of it,” he adds.
The increasing use of 3-D composite printing also opens up possibilities for robotics and AFP. Composites manufacturers could build an AFP structure on top of 3-D printed tooling, 3-D print features onto an AFP structure or overwind 3-D cores with selective AFP reinforcement. “That’s one of the big benefits of AFP technology. You can selectively reinforce in whatever angle or path or section that you want robotically,” Marcario says. The combination of manufacturing methods makes it possible to produce structures that couldn’t be made with just one technique.
At Concordia University in Montreal, researchers have been using AFP and robotics for many different types of products. “You can do things that are unique and that cannot be done using any other technique,” says Suong Van Hoa, professor in the Department of Mechanical and Industrial Engineering and editor of the book “Automated Composites Manufacturing”.
Hoa says automated production offers many other advantages. For example, using robots to produce large parts like an airplane fuselage will eliminate the variability and waste that result when many different people do lay-up. Operators can also steer the fiber, varying the orientation from place to place to optimize the design and performance of a structure.
Concordia University’s researchers are also using automation to develop new types of fabric laminates, bypassing the weaving machine by strategically laying down different tows in different position.
The university has recently been exploring robotics for the 4-D printing of composites. In 3-D printing, a robot can deposit composite materials to build, layer on layer, a product of very complicated geometry. With 4-D printing, a robot can deposit the layers down flat and the part changes shape as it cures.
Robots have traditionally been used for teach/repeat functions; once they learn what spot to go to, they return to it every time. But composites manufacturing is not exact and product tolerances can be large, so companies may have to change robot positions to work on each part, according to Christopher Blanchette, national account manager, aerospace and assembly for FANUC America, a company that specializes in robotics automation.
Today’s intelligent robots can provide the flexibility needed to adapt to composite parts’ changing geometries based on feedback from sensors. Using the automated systems that monitor and control the robot’s input, operators can achieve more precise results than they can through mechanical adjustments or general calibrations.
>> Read more by Mary Lou Jay, Composites Manufacturing, September 5, 2017