Fraunhofer to demo carbon fiber thermoplastic placement system

Lasers near the laying head will melt the thermoplastic just before the carbon fibers are placed on the tool.

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Research group Fraunhofer Institute for Production Technology (Aachen, Germany)) announced on March 23 that it's JEC Composites Show 2010 exhibit will include a demonstration of a system for automated placement of fiber-reinforced thermoplastic composite materials.

In the system, carbon fibers are integrated into kilometer-long strips of meltable thermoplastic resin. The resin is heated by a laser just before fibers are placed, and then the entire laminate stack is compressed into a compact structure. This way, the tape strips fuse with each other and cool off quickly because the laser rapidly emits precisely measured doses of energy in a targeted manner.

Fraunhofer researchers also will present a new joining laser-based technology for glass- fiber-reinforced thermoplastics. "All we need for this is a laser that emits infrared light," explains Wolfgang Knapp of the Fraunhofer Institute for Laser Technology ILT. "The infrared laser melts the surface of the plastic components. If you compress them when they are still fluid and then let them harden, then the result is an extraordinarily stable bond."

"The know-how sticks in the process control: in determining the gap between laser head and surface; in controlling the time which the laser beam lingers on substrate; in calibrating the pressure." With the infrared laser, any components made of thermoplastic composites can be welded together –  load-bearing structures for cars, components of boat hulls, rocket tanks.

"The new joining techniques are suitable for all thermoplastic materials that are subjected to extreme strains," concludes Knapp, who is coordinating the Fraunhofer joint exhibition booth. "Because fiber composites are not only stable, they are also lightweight and they save energy with any type of acceleration – no matter if by land, sea, in the air or in space."