Printing composites in 3D, or additive manufacturing (AM), involves using successive layers of material, such as kevlar, carbon fiber or fiberglass, to form a finished product from a three dimensional computer model.
3D printing, or additive manufacturing (AM), describes the process of using successive layers of material, typically plastic extruded out of a computer-controlled head, to form a finished product from a three dimensional computer model. In recent years, 3D printing has expanded to include composite materials such as fiberglass, Kevlar, and carbon fiber.
Carbon fiber is traditionally made from strings of carbon atoms that are aligned parallel to the central axis of the fiber. These fibers can then be used as is or woven into sheets to be incorporated into finished products. Carbon fiber has strong mechanical properties, is flexible, and conducts heat and electricity well. It’s only downsides are the cost of production and the long amount of time required to use, because it must be incorporated into products by hand.
Because of the expense associated with using carbon fiber, objects that make use of it are usually composites, and not 100% carbon fiber. The carbon fiber is then added only in places that require extra reinforcement or conductivity. MarkForged’s Mark Two 3D printers have two printing heads, allowing them to print carbon fiber within a larger object made of a material like plastic or nylon.
University of Bristol - Modified Traditional 3D Printer
In January of this year, researchers from the University of Bristol in the UK announced a new method of 3D printing composites. Their method involves using ultrasonic waves to drive the reinforcement fibers into position within the liquid polymer matrix. Once the fibers are in position, a focused laser beam sets the microstructure and hardens the matrix of epoxy resin.
This process works because “the ultrasound effectively creates a patterned force field in the liquid plastic and the fibers move to and align with low pressure regions in the field called nodes,” according to Tom Llewellyn-Jones, the PhD student who developed the process. The laser was then mounted onto a standard 3D printer modified to print the epoxy/fiber mixture. Using their process, the team was able to reach printing speeds of up to 20 millimeters per second. That rate is on par with traditional 3D printers today.
This process offers the opportunity for full customization of 3D printed composites in the future, because nearly any type, shape, or size of fiber can be used, allowing for many different types of composite materials to be printed, much more than the three currently offered by the MarkTwo system. Additionally, this process offers much greater control over the composite microstructure (the alignment of the fibers can be altered by changing the standing wave pattern of the ultrasonic waves) than the Mark Two, which uses a continuous fiber system.
In the future, this technology can be used in many different industries, from smart materials like resin-filled capsules in self-healing materials to piezoelectric particles for energy harvesting. This technology could also be used in space travel, giving astronauts the ability to replace damaged composite pieces on their spacecraft or satellites while in orbit, saving both money and time for agencies like NASA.