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Faster Brazing in the Roof Joint





               Task                                               Result


               Since the mid-90s brazing has been used in automotive   Both the brazing speed and the joint quality were
               manufacturing. The advantages of brazing are most   increased using the Laserline diode laser. By working in
               apparent when it is used in class A show surfaces. Low   the focus of the top hat laser beam, a better distribution of
               warpage, a stiff joint ready for the paint shop, and almost   the power density into the boundaries of the joining
               no post-processing make it a unique process. Compared   partners was achieved. With the diode laser, edge notches
               to laser welding or spot welding, laser brazing improves   were reduced by 75 percent and maximum process speed
               the aesthetics of a joint so dramatically that the usual   increased to 4.4 m/min. Volkswagen decided to replace all
               plastic strip needed to cover it can be omitted. The   YAG lasers used in the Touran production line with 6 kW
               brazing process was first made possible by fiber-coupled,   diode lasers. Today, Volkswagen Group uses numerous
               lamp-pumped Nd:YAG lasers. In 2001 the diode laser   diode lasers from 3 to 6 kW worldwide.
               made its debut as a brazing tool in the manufacturing of
               the tailgate of the Audi A3. Typical process speeds were
               initially 2.4 m/min. To increase production figures,
               Volkswagen set a goal of improving brazing speed without
               compromising quality.
               Process


               At the VW Touran production line in Wolfsburg, a process
               comparison was conducted between a 4 kW YAG laser
               and Laserline’s 6 kW diode laser. While the existing YAG   Material: Zinc coated steel sheets
               laser used a defocused beam, the new diode laser was   Task: Increased process speed for laser brazing
               set up with the beam in the focus position and a 3.2 mm   of roof joints
               diameter focus. The trial examined the quality of the joint   Laser: LDF 6000-100
               at higher process speeds as well as the process stability in   Optics: Tactile brazing head with CuSi3 filler wire
               series production.
                                                                  Brazing speed: 4.4 m/min








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