Brazing

High process speed - low heat input - smooth, sealed and clean brazing seam

The process

Joining methods, in which the brazing solder is melted with the help of an industrial laser, have established themselves mainly in the mass production of vehicle bodies. There, laser beam brazing is mostly used for joining galvanized metal sheets or lightweight components out of aluminum. Laser brazing is usually realized with a brazing optic that is integrated into a robot. The laser beam is guided along the joint, where it melts the brazing solder - e.g. a copper-silicon-wire - and connects the components with this. The success of the process is attributed to a firmness that is similar to welding seams and the high aesthetic quality of the joints: brazing seams, generated with lasers, are known for their sealed, smooth and clean structures. This is visually attractive and reduces rework to a minimum. Car body construction, for example, can often be lacquered immediately after cleaning.

Process advantages of the diode lasers

In the field of laser-based brazing, Laserline's diode lasers have established themselves worldwide for their practical use. Over 800 LDF diode lasers are in successful permanent use all over the world with different applications in the automotive body assembly. Besides the requirements for high firmness and a preferably narrow heat-affected zone, there are particularly high demands to the appeal of the joint for visible seams. A major process advantage of diode lasers is the striking calm molten pools.

Additionally, enormous process advantages are achieved by Laserline's Multi-Spot-Modul used for brazing with triple spot: Even with the often difficult brazing of hot-dip galvanized sheets, this technology can achieve, as usual, high brazing seam qualities without process speed reduction.

Brazing with triple spot

Application examples

Hot-dip galvanized zinc brazing with triple spot

In the production of vehicle bodies, laser beam brazing has long secured for itself pride of place. However, the increased use of hot-dip galvanized sheets has of late led to problems: the number of micro splashes and wavelets has been growing, requiring a reduction in the process speed. With a variable multi-spot module, in which side-spots are positioned in front of the main spot, Laserline has developed a groundbreaking solution: the pre-spots ablate the galvanizing at the brazing seam and thus calm the brazing process, which could then be carried out at the normal speed. This process is rated as a trend-setter.

Brazing of galvanized sheets

When still galvanized sheets (that means electrolyte-supported) are processed - we also talk about “elo-zinc” - for brazing diode lasers with a classical single spot are sufficient. Here, the beam source is mostly integrated into special brazing robots. Thanks to the calm molten pools created by diode lasers, melting of the typical brazing solders based on silver or whitish silver poses no problem at all. Well-designed seams with high quality are the end result.

In a process comparison between a 4 kW YAG and a 6 kW diode laser during the production of the VW Touran in Wolfsburg, Germany, the process stability of the LDF diode laser in mass production could be tested.