Product Code: ICAL06_903

Humping in Welding with Single-Mode Fiber Lasers
Authors:
Frank Vollertsen, BIAS Bremer Institut fuer angewandte Strahltechnik GmbH; Bremen Germany
Claus G Thomy, BIAS Bremer Institut fuer angewandte Strahltechnik GmbH; Bremen Germany
Florian Wagner, BIAS Bremer Institut fuer angewandte Strahltechnik GmbH; Bremen Germany
Thomas Seefeld, BIAS Bremer Institut fuer angewandte Strahltechnik GmbH; Bremen Germany
Presented at ICALEO 2006

Recent developments have made available single-mode fiber lasers with beam powers up to 1 kW. With these laser systems, it is possible to cover the whole range of micro welding applications from penetrations of several tenths of mms and welding speeds well exceeding 100 m/min up to the macro range with penetrations exceeding 2 mm and welding speeds of several meters per minute. However, when welding steel at higher velocities, melt pool instabilities have to be experienced, leading to the so-called humping phenomenon. Within this paper, results of a study on humping with a single-mode fiber laser with a maximum beam power of 1 kW and a beam quality M2 < 1.05 will be presented. Aside from assessing the influence of power on the start of the humping phenomenon, the influence of spot size, focal length and beam incidence angle is investigated. Moreover, a model based on a modification of the Rayleigh theory is suggested and applied to a wide range of welding speeds.