Authors: Dieter Schu÷cker, Joachim Aichinger, Georg Schu÷cker
If relatively thick workpieces are cut with a laser severe quality defects appear as enhanced roughness and adherent slag. The latter quality degradations must be caused by dynamic phenomena taking place in the liquid layer formed at the momentary end of the cut kerf. Therefore a theoretical analysis of the latter zone has been carried out that shows that surface tension plays a major role and causes an intermittent ejection of melt that is finally responsible for fluctuations of the volume of the molten body leading to roughness of the cuts. The latter intermittent melt removal can also be shown to cause adherent dross and slag. A mathematical evaluation of the latter considerations shows good coincidence with experiments.