Micro Processing of Metals Using a High Repetition Rate Femtosecond Laser: from Laser Process Parameter Study to Machining Examples

摘要

The paper presents a study of laser micro processing ofrnmetals by using a high repetition rate femto secondrnlaser. On stainless steel (AISI 304), copper andrnaluminium the impact of the significant laserrnprocessing parameters onto the machining process wasrninvestigated, such as laser fluence, repetition rate,rnlateral pulse distance and polarisation. The machiningrnresults were evaluated by the ablation rate, surfacernroughness, process efficiency, material removal raternand the wall-angle. For complementary discussions thernexperimental data were compared with resultsrnachieved in theoretical analysis. Outgoing from thernresults appropriate laser processing parameters werernderived in order to optimise the machining process.rnWith the application of ultra short laser pulses highqualityrnmachining results with a minimal thermal loadrnand a roughness R_a of the laser processed surface ofrnonly some hundreds nano meter were obtained. Onrnother hand high machining throughputs were achievedrndue to application of high repetition rates. Finally, thernpossibilities and the limits of the high repetition raternfemto second laser technology in laser micrornprocessing are demonstrated by means of threedimensionalrnmicro structured machining examples.