Product Code: ICAL06_402

Inert Cutting of Medium Section Stainless Steel Using a 2.2kW High Brightness Fibre Laser
Authors:
Martin Sparkes, The University Of Cambridge; Cambridge Great Britain
Markus Gross, The University Of cambridge; Cambridge Great Britain
Steven Celotto, The University Of cambridge; Cambridge Great Britain
Tao Zhang, The University Of cambridge; Cambridge Great Britain
William O'Neill, The University Of cambridge; Cambridge Great Britain
Presented at ICALEO 2006

A 2.2KW fibre laser was used in a series of inert cutting trials on stainless steels, thickness in the range of 6-8mm. Variations in the cutting performance with changing gas pressure, focal position and nozzle diameter were investigated. Results showed the difficulties associated in cutting with high brightness lasers, specifically in obtaining full melt eject through narrow kerfs; two distinct melt eject failure mechanisms being observed. Failure of melt removal in the upper region resulted in melt ejecting out of the top surface, poor base ejection giving recast and dross problems on the base of the cut, detailed SEM images being presented. Consideration of fluid dynamic models is used to show distinct differences in the theoretical gas performance at the centre of the cut, displayed by most models, and at the edges were the melt eject is taking place. Melt eject is also shown both experimentally and theoretically to be improved for these experiments by the use of smaller nozzles. With a change in focal position strong correlations between the theoretical laser path, and the cut edge with variation in focal position were observed. The performance of the melt eject is shown with respect to speed, pressure and kerf width. Improved cut edges being seen at higher speeds, higher pressures, smaller nozzles and wider kerfs. Processing parameters were not optimised to take benefit of the high brightness of the laser. Speeds were seen to be around 1.5 times higher than those of the CO2 with corresponding powers, processing parameters being very similar.