Caption: Demonstration of a welding seam on a car door with RobScan (Source, Daimler)

It took five years to design and develop RobScan, which is now used in major series production operations. The RobScan technology is employed, for example, to make some 650 welded joints for the doors, side panels, rear-end middle piece, and rear hatch on the Mercedes-Benz C-Class. Such welds replace roughly 15 percent of the resistance spot welds previously used. RobScan has increased welding speed and improved welding quality. 

In principle, welding with laser beams is not new. However, the speed of the RobScan laser welding process, which was developed in the DaimlerChrysler Research Center in Ulm is something quite different. The process is not only five to ten times faster than the conventional electric resistance spot welding currently used in body construction, it is also much more flexible. The laser beam used by RobScan is generated by a solid-state laser with high output, short wavelength, and excellent beam quality. The beam from the disk laser can be concentrated extremely accurately. Mounted to the end of the robot arm, the scanner head uses two electronically controlled adjustable mirrors to move the highly concentrated laser beam from one welding spot to the next at lightning speed.

During each welding operation, the steel robot arm continually moves along the components while the scanner head simultaneously guides the laser beam "in flight" across it (welding on the fly). This makes it possible to weld seams of the highest quality and precision at the fastest possible speed. With RobScan it takes only milliseconds to move from one seam to the next. While in electric resistance spot welding the electrode holder has to grab the work piece from two sides, in laser welding it is sufficient to have contact-free access to one side, which opens up completely new possibilities for assembly.

DaimlerChrysler experts expect considerable cost reductions in body construction with the use of this new welding process in serial production. Thanks to the high processing speed it is now possible to make a lot more spot welds at one single station than before. This also means that the number of welding stations can be reduced, which decreases the overall size of the assembly area. The fabrication hall of the future could contain a pool of laser beam sources with a widely branching glass fiber network leading to the different processing stations.

On May 8, 2008, the Laser Technology 2008 Innovation Award presented by Arbeitskreis Lasertechnik e.V. and the European Laser Institute (ELI) was accepted by the spokesman for the Daimler AG team, Bertold Hopf, head of Material and Production Technology, Dr. Klaus-Dieter Debschütz, head of Materials, Production Technology, and Vehicle Body Concepts at Group Research in Ulm, and RobScan project manager Holger Schubert.