High-power fibre lasers for materials processing haveundergone a rapid development process within thepast two years. The modular structure of the systemshas, in this short period of time, enabled the scalingof laser power from several hundreds of Watts to 10Kilowatts and potentially even more. Due to itsspecific advantages, among which there are a beamquality significantly improved compared to othersolid-state lasers, a high energetic efficiency and acompact size, they might well be considered to be afuture alternative (in view of technical and economicaspects) to both Nd:YAG- as well as to CO2-Lasers.However, principle studies on its readiness forwelding steel and aluminium alloys are still lacking.Thus, at the BIAS Bremer Institut für angewandteStrahltechnik GmbH, a basic experimentalprogramme on welding of various steel andaluminium materials with a fibre laser possessing amaximum beam power of 6.9 kW was performed.The central aim of the experiments was to explore thepotentials of this new type of laser and demonstrateits ability to enhance the process limitationsconsidering welding speed and sheet thicknesspreviously regarded to be inevitable when weldingwith solid-state lasers.Compared to Nd:YAG-Lasers with a maximum beampower of 4 kW (nowadays a standard laser inindustry), the penetration depth could be significantlyincreased. E.g., a penetration depth of up to 8 mmwith a sufficiently narrow seam width could beachieved, and for sheets of 3 mm thickness, anincrease of laser power from 4 to 7 kW nearlydoubles the possible welding speed. For aluminiummaterials, very stable processes have been obtainedeven at a welding depth of more than 6 mm.In general, the results have been so promising for allmaterials tested that first studies on other industriallyrelevant joints such as overlap joints of zinc-coatedsteel or aluminium have been conducted.
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