Laser welding of aluminum: extended processing potential by different wire positions

Aluminum alloys are getting increasingly interesting not only for the classical application in the aircraft industry, but also in rail and road vehicles and the aggregate manufacturing as well as in many other fields of the metal processing industry. The laser is rarely found as a tool for joining aluminum in series production, up to now. Among others, this is due to the fact that only few instructions for the design of an appropriate joining geometry are available in the literature. In addition, neither hints concerning the laser's suitability for industrial application are provided nor essential issues for series production by lasers are to be found, such as e.g. acceptable tolerances regarding the joining geometry. In this paper, exemplary solutions to the problems mentioned above are presented, resulting from the application of a 3 kW fiber-guided Nd:YAG-Laser for tasks in the automotive industry. Taking the example of an overlap joint geometry on the one hand, and the connection of two extrusions forming a 'T-joint-geometry' on the other hand, there will be shown which tolerance fields exist and in which way and up to which extent a gap can be bridged, not only in a gravity position. In addition, results will be presented, demonstrating that the energy coupling as well as the melt pool dynamics can be influenced by varying the wire position or using a second wire in an adequate position. Concerning an overlap joint, gaps of more than the doubled size can be bridged with this technique.