Laser beam characteristics of handheld laser beam welding systems

As the use of hand laser beam welding (HLBW) is rapidly increasing even in regulated areas, it is important to use a defined and robust configuration, including parameters, to ensure a reliable process. To this end, it is important to understand the influencing factors and their effects on the resulting properties. For this purpose, several commercially available systems were tested and characterized.The laser beam properties of the systems examined vary, e.g., in terms of beam waist diameter, power distribution, beam quality factor M2, beam divergence, focal shift, and beam oscillation options. The main difference in these systems includes the type of laser source (single-mode and multi-mode) and maximum power. After characterizing the systems, welding tests were also carried out with different materials, including different steel types. Porosity and appearance of weld seam were selected as the main criteria for evaluation. Based on the results, it can be concluded that it is not possible to simply transfer optimized process parameters or a Welding Procedure Specification (WPS) between different systems. Imperfect designs of the optical setup may result in focal shifts exceeding the Rayleigh range which, in turn, can be the cause for weld anomalies, e.g. reduced penetration depth. This publication focuses primarily on the differences in laser beam properties.