Lightweight vehicle construction thanks to lasers

When joining sheets with conventional spot welding it is necessary to overlap the edges. By comparison, welding with a laser beam makes possible flangeless designs. Here the individual sheets are first assembled by way of tongue-and-groove joints and then welded by the laser. This offers several advantages: processing time drops when compared with spot welding; the elements thus joined can be of differing materials and thicknesses; the resulting structures have no redundant material and thus save weight. In addition, the prepositioning of the parts one with another reduces the – otherwise enormous – effort for clamping technology, permitting simple and cost-favorable clamping aids.

Non-flanged structures, when compared with conventional spot welding, offer many benefits in regard to processing time, material use and the weight.

Where greater loads demand additional stability, reinforcing structures can be attached as needed. The corresponding structures – such as the underbody of a vehicle – can be made up with less tooling. Neither are any special tools required for this purpose, which have to be manufactured in an elaborate process when preparing for production. Instead, all the required steps in processing can be carried out by a standard laser welding robot.

One outstanding example of this process is the “StreetScooter” deployed by the German Post Office. It was engineered by an academic spin-off of the Rhenish-Westphalian Technical University at Aachen, Germany, and is built on an underbody made up without flanges. At present about 40 of these microvans are in trial use, which has been thoroughly successful to date.