Composite printing process focused on scale, speed

With roots in the boat manufacturing industry, Ken Tyler felt there had to be a better way to fabricate composite parts than the mostly manual, labor-intensive methods practiced throughout his industry. With some experience in 3D printing, he built a prototype 3D printing machine based on UV curing, proved its feasibility as a means to rapidly manufacture composite shapes and parts with a variety of continuous-fiber reinforcements (glass, Kevlar and carbon fibers), and led a patent on the process in 2012. Tyler says the technology, called continuous scaled manufacturing (CSM), is past the proof-of-concept stage and his company, Continuous Composites (Coeur d’Alene, ID, US), is exploring fully commercial applications in a variety of markets.

Having improved the process to print with 8- and 16-channel “extrusion” nozzles, Tyler says the technology is currently capable of printing at speeds up to 120 inches/minute, with an upper potential speed, based on the UV-curable resin’s demonstrated cure rate, of 1,200 inches/min. The resin, a thermoset acrylate, has a post-cure, glass transition temperature (Tg) of more than 300°C and a strength modulus of 1,400 MPa.

Compared with conventional composites fabrication methods, the CSM 3D printing process offers several unique attributes. One is the ability to easily make parts with functional materials, such as copper wire and fiber-optics, interspersed throughout the matrix along with the fiber reinforcements. In one demonstration project, the company printed a functional heater, comprising a single filament of nichrome wire embedded in a layer of fiberglass with another layer of fiberglass printed over it. Such heaters eventually could be used for de-icing wind turbine blades or aircraft wings. Using a similar composite construction with fiber-optics, Tyler says, can turn any part into a “strain gauge,” providing a real-time way of measuring torsional stresses in structural composite parts, which potentially could be used to detect voids and cracks in finished parts.

Tyler allows that the process will not be able to achieve fiber volumes as high as an autoclave-cured prepreg laminate, but believes once his process is fully commercial, CSM will be competitive with, if not less costly than, common composites manufacturing processes. “We aren’t competing with injection molding, but with other fabrication processes which, for the most part, are time consuming and wasteful.”