Burscheid, Germany - Quality was the focus of attention when the Mercedes-Benz C-Class went into series production. The same principle was applied by Johnson Controls (www.johnsoncontrols.com), a supplier of automotive interior systems, electronics, and batteries. Intensive collaboration between the automaker and supplier prevailed for the duration of the project and resulted in a number of innovations.
As a pioneer in laser remote welding technology for automotive seating, Johnson Controls came up with a unique method of producing sandwich structures for the rear-seat backrests. After experts came up with a rear-seat backrest design suitable for laser processing, it was possible to use laser remote technology alone, reportedly for the first time ever in the production of a large-scale series component.
This process involves directing the high-energy laser beam into an optical system and then using mirrors to redirect it at high speed to the individual welding points on the component. Because only the mirrors have to be moved mechanically, the welding process is up to six times faster than traditional methods. Other advantages of this technology include the fact that the weld seam is up to 25 percent stronger.
Because the laser beam can be moved into any position at a given level, a range of variation in length, geometry, and number of weld seams is possible. This means that panels can be joined individually to take account of the relevant stresses, which has a positive effect on the resultant design options. In addition, dimensional tolerances and precision also are improved because less heat is applied to the component than in a conventional spot-welding process.
This laser welding process also generates production benefits for Johnson Controls, because the standardized plant technology is product-independent. This means that a single machine can produce up to four different components simultaneously and also can be used to manufacture all customer variants simply by changing the tool. When a variant change occurs, the quick-change system requires only a different clamping tool to pick up the individual components prior to welding.
A knee airbag also has been incorporated for the first time in large-scale series production, including a laser weakened, predetermined breaking point below the steering column to permit its release.
Commenting on these developments, Matthias Berg, vice president and general manager DaimlerChrysler Customer Business Unit at Johnson Controls, said, “Close collaboration between the project teams has shown that it is possible to continually identify and implement new enhancements, even for well-established products.”