Laser beam micro-welding with single mode fibre lasers

Abstract

Single mode fiber lasers, which are available with laser powers of more then 1 kW, enable the welding of thin sheet materials. Although laser power is comparably low, the excellent beam quality of M2 < 1.1 provides intensities sufficient for keyhole welding. Especially for micro-fabrication, it is now possible to weld at considerable processing speed of 100 m/min and more, whilst heat input and thus distortion is minimized. Moreover, the weld pool and thus weld geometry is very narrow, consequently reducing the risk of weld imperfections due to weld shrinkage. Within the framework of this paper, the topic of keyhole welding of thin steel, copper and aluminum sheets is addressed. Based on fundamental studies concerning welding speed and welding depth relations vs. power and energy density for various base materials, the potentials for low distortion high speed processing are assessed.Single mode fiber lasers, which are available with laser powers of more then 1 kW, enable the welding of thin sheet materials. Although laser power is comparably low, the excellent beam quality of M2 < 1.1 provides intensities sufficient for keyhole welding. Especially for micro-fabrication, it is now possible to weld at considerable processing speed of 100 m/min and more, whilst heat input and thus distortion is minimized. Moreover, the weld pool and thus weld geometry is very narrow, consequently reducing the risk of weld imperfections due to weld shrinkage. Within the framework of this paper, the topic of keyhole welding of thin steel, copper and aluminum sheets is addressed. Based on fundamental studies concerning welding speed and welding depth relations vs. power and energy density for various base materials, the potentials for low distortion high speed processing are assessed.