V. Wippo
C. Henkel
J. Kuklik
P. Jäschke
S. Kaierle

Laser Transmission Welding With A Multi-Focal Optic

Proc. International Congress on Applications of Lasers & Electro-Optics (ICALEO)
Type: Zeitschriftenaufsatz (non-reviewed)
Laser transmission welding is an established welding technique for unreinforced and short glass fiber reinforced thermoplastics. In many cases, the weld seam width is small (e.g. microfluidic applications, welding of electronic components and containers). However, the number of applications needing wider weld seams is growing in the automotive and aerospace sectors. In order to generate wide weld seams (above several mm) homogenizer optics are used. The welding of small radii is problematical with these optics because of an inhomogeneous heat generation. In order to overcome this problem, a special welding head was build consisting of nine independent controllable spots in order to be able to vary the intensity distribution within a laser focus in terms of location and time. This makes it possible for the first time to partially adapt the laser power depending on the weld path. The core part of the welding head is the optical assembly, which allows a homogeneous intensity distribution as well as adapted ones for example to weld small radii. The functionality was tested by bead on plate welding monitored by a thermo camera, allowing observation of the heat generation. In order to determine the weld seam quality, cross sections were prepared and examined for cavities related to the welding process. Afterwards the results were correlated to the used energy distribution.