Increasing the Joining Depth of Laser Welded Metal Layers in Metal-Polymer Sandwich Composites

When joining sandwich panels that are used in automotive and aerospace industries, there are issues regarding the thermal degradation of the core polymer layer. The use of two-sided pulsed-periodic laser welding allows to reduce the thermal impact on the polymer layer. Welding of a three-layer composite material consisting of two metal layers and an inner polymer core was carried out. A weld depth of at least 70 % of the thickness of the outer metal layer was achieved. Focusing the laser beam into a segment-shaped spot provides an opportunity to enhance the butt joints of metal-polymer sandwich composites by creating weld connections with a larger cross-sectional area and minimizing deformation. At the same time, diffractive optical elements (DOEs) can be used to control the properties of such joints.