Automated and Robot Guided CFRP Cleaning with a Compact Excimer Laser

Carbon fiber reinforced plastics (CFRPs) are composite materials that offer a unique and highly desirable combination of physical strength and light weight. During processing, the residue on surfaces has to be removed. Various mechanical and chemical methods have been explored for the removal of these surface contaminations, but unfortunately, each of these methods has its own drawbacks.

The pulsed excimer laser at a wavelength of 248 nm has emerged as a promising tool for this task, while avoiding any damage to the CFRP fibers. Mobile excimer laser system solutions expand the applicability when it comes to large aircraft structures. The Fraunhofer IFAM in Bremen, Germany is working to develop a compact excimer laser-based solution that lends itself to robotic automation. Excimer laser surface preparation is a single-step, dry process that is capable of delivering superior results over other methods, and has proven to be highly reproducible, making it a consistent and stable process that is well-suited for volume production applications and even repair work. Furthermore, this same technology is applicable to cleaning of delicate surfaces in many other applications.

The base is a Coherent “ExciStar 1000” excimer laser to be mounted on the end of a robotic arm and then rapidly moved over the surface of the part to be processed, following the 3D part contours as necessary. The high repetition rate (1000 Hz) and pulse energy (10 mJ) allow rapid processing and continuous movement of the laser beam over the part surface. Typically, every point on the CFRP structure is exposed to between two to ten laser pulses, which provides complete removal of surface contaminations. Processing speeds of up to 10 m2/h are attainable using this method.

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