In recent years laser brazing has become widely accepted as a reliable joining technology for visible joints in car body manufacturing. There are, however, numerous requirements with regard to system technology that have to be met in order to guarantee a faultless application. According to state of the art in series production, it is not yet possible to avoid sporadic brazing defects which call for a subsequent hundred percent inspection of the components.

It is therefore the aim of a research project carried out by the Bavarian Laser Centre in cooperation with the company ERLAS GmbH and other partners, to extend the process limitations of laser brazing by means of temperature control and thus to guarantee faultless seams. A flexible brazing head with integrated temperature measurement was constructed for this purpose and connected to a fibre-coupled high-power diode laser. The process parameters are systematically varied in order to deliberately produce defective brazing seams. The measurement signals thus detected are characterised with regard to significant attributes.

The developed system technology permits a selective control of the laser brazing process and the detection of process failures.