Due to its very good electric and thermal conductivity,copper is an important material with a wide range ofapplications, which require an efficient and reliablewelding process, preferably with laser beams. Thesame material properties make laser welding of coppera challenging task. To achieve welds with penetrationdepths of several millimeters in copper usingcommercially available laser sources relatively lowfeed rates below 10 m/min are needed. Welds incopper at such low feed rates with 1 μm wavelengthlasers often suffer from numerous weld seam defectssuch as melt ejections and pores.In this paper welds in copper using different laserwavelengths will be presented. Due to a higherabsorption green laser light (515 nm wavelength) isobviously far better suited for welding copper. Hencethe potential of green laser light on welding copper isdiscussed. Furthermore the influence of powermodulation during copper welding on weld defects isshown. Presuming the correct parameters, modulationof the power shows very distinct advantages. On theone hand a strong reduction in number of weld defectswas measured. On the other hand a significantly moreregular and homogeneous solidified weld seam surfacefor the modulated welds was achieved. Welding resultsfor different copper alloys using laser powermodulation with different laser wavelengths arepresented. Furthermore the influence of the modulationfrequency is discussed.
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