Making Seals safe

© Fraunhofer IIS
The system for rapid and precise surface testing is fully automatic.

“Seal Inspector” tests polymer sealing rings using laser lines

Without noticing it, people come into contact with these unspectacular looking and easy to construct plastic parts on a daily basis. We are talking about polymer sealing rings. They play an important role in many areas of our lives, above all in our vehicles. For example, they are fitted in air­conditioning units and in braking systems, where their role is generally to ensure that no liquids leak out. Whereas the consequences of a faulty seal in an a/c unit are easy to deal with, the failure of a seal inside a braking system can pose more serious problems.

To objectively and reliably detect even tiny surface defects, researchers at the Development Center for X-ray Technology have worked with the company “miho Inspektionssysteme” to develop the “Seal Inspector” testing system, which meets the requirements of industry from the points of view of both cost effectiveness and the technology itself.

The centerpiece of the testing system, which was developed by Fraunhofer researchers, consists of a high-resolution measuring unit and evaluation software specially developed for this application. The measuring unit records the surface of the sealing rings from all sides in 3D. This is achieved by projecting several laser lines onto the different sides of the sealing ring and recording their paths on the ring using special cameras. From this measurement data, the evaluation software reconstructs the entire surface and, in a subsequent step, securely detects all relevant anomalies. Initial testing systems based on this system concept have been successfully integrated in production, demonstrating the suitability of this technology for the rapid, precise surface testing of goods that are mass-produced in their millions. The measurement principle used in the technology opens up a wide range of possible applications whenever there is a need for rapid, high-resolution surface testing.