Holo/OR, industrial partner of LASER COMPONENTS, has developed a diffractive optical element (DOE) that accelerates the laser brazing process for hot-dip galvanised metal sheets. It provides better melting performance and cleaner edges at the same time. The DOE made of UV fused silica has an efficiency of 90%. It forms three beams with different diameters and power levels. Two smaller stripping beams ensure that the zinc coating is preheated, cleaned and preconditioned for brazing.
The large centre beam performs the actual brazing process. Its homogeneous energy distribution ensures that the brazing material is melted evenly. So far, similar results could only be achieved with several lasers or complex optomechanical elements.
Laser brazing uses a laser to melt the brazing material and join two metallic components together. In contrast to the welding process, the parts themselves are only minally heated. In the case of hot-dip galvanised sheets, this means that the zinc layer evaporates only in a very limited area and the sheets are hardly deformed during processing.
Providing connections with high mechanical stability without impairing the corrosion protection, laser brazing has become an important process in the automotive industry. Oxides and impurities in the zinc layer of the soldered seam can cause irregularities, e.g. splashes, pores and uneven surfaces. This effect is now prevented by the new DOE.