2 September 2003 Double focus technique: influence of focal distance on the welding process
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Proceedings Volume 5121, Laser Processing of Advanced Materials and Laser Microtechnologies; (2003) https://doi.org/10.1117/12.520910
Event: Laser Processing of Advanced Materials and Laser Microtechnologies, 2002, Moscow, Russian Federation
Abstract
The main goal of welding aluminium with double focus technique is to improve the quality of the welding result, that means to reduce porosity and to avoid melt ejection. The idea behind this approach, namely utilizing two or more individual focal spots on the workpiece instead of just one, is to shape the keyhole geometry such that the tendency of a keyhole collapse is considerably reduced. With one spot or with a small distance between the two laser spots, the weld bead is irregular and a high number of process pores can be observed. With a larger focal distance the bead is becoming stable and the porosity is reduced dramatically. At the same time, however, the welding depth is decreasing compared to the situation with a small focal distance. The best quality was achieved at the focal distance 0.6 mm. In this case, pores which are larger in diameter than 0.6 mm were avoided completely and the number of smaller pores is strongly reduced. After a further separation of the keyhole the number of pores increases again. Whereas the process quality can be improved by appropriate arrangement of the spots some reduction of the process efficiency might occur.
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Andreas Russ, Wolfgang Gref, Markus Leimser, Friedrich H. Dausinger, Helmut Huegel, "Double focus technique: influence of focal distance on the welding process", Proc. SPIE 5121, Laser Processing of Advanced Materials and Laser Microtechnologies, (2 September 2003); doi: 10.1117/12.520910; https://doi.org/10.1117/12.520910
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