Optimization of laser process conditions for cutting of thin metal and polymer sheets with femtosecond laser

摘要

In this paper the results of micromachining of polycarbonate polymer foils and SUS304 stainless steel thin sheets are reported, performed by an industrial femtosecond laser operated at 1030 nm and 515 nm (SHG) wavelength. For a typical Galvoscanner setup the ablation scribing was investigated at a spotsize of 20 urn which is typical for contemporary feature size used for medical stents. At this value a maximum peak intensity of 6.4*10~(13) W/cm~2 can be reached, which enables significant nonlinear absorption in the polymer. Laser pulse overlap was varied to optimize overlap values for best edge quality and for best ablation rate. From the results some guidelines for complete cutting of thin sheets were derived. For an acceptable edge quality a maximum ablation rate of 2.6 mm~3 min was demonstrated for stainless steel thin sheets, whereas up to 9,4 mm~3 min have been reached for polycarbonate. For SUS304 the use of the SHG does not increase ablation rate or edge quality, whereas for polycarbonate the cutting quality is better, but at a smaller ablation rate.