The quality of laser beam welded seams is strongly influenced by hydrodynamic processes of the liquid material. One phenomenon with negative effects on the seam quality is the so called “humping effect” which occurs at high welding speed.
New types of solid state lasers are allowing reduced focus diameters and consequently higher beam intensities. These improvements can be transferred into increased welding speed.
Under the aim to optimize the high speed welding process using solid state lasers with improved beam quality different aspects of humping have been investigated experimentally as well as theoretically. This includes investigation of keyhole formation as well as melt pool dynamics.
Different measures to prevent humping especially by slowing down the melt flow velocity have been investigated. It has been demonstrated that by adaptation of focus diameter or using of twin spot focus technique with accommodated focus distance humping can be shifted to higher welding speed from less than 20 m/min to more than 45 m/min.