Statistical Analysis and Modelling of an Yb: KGW Femtosecond Laser Micro-drilling Process

Femtosecond laser drilling is capable of economically drilling a number of closely located holes on micro-scale. Different characteristics or acceptance criteria like geometric and metallurgical factors are used to judge the quality of the drilled holes. This paper aims to evaluate the quality of micro-holes, which were drilled by Yb:KGW laser end-pumped by high-power diode bars. The geometric factors included hole roundness, hole taper and variation in hole entrance diameter. The metallurgical factors included recast layer and micro-cracks. The process parameters that most affected the hole quality were identified by the analysis of a full factorial design. Optimum hole characteristics on stainless steel sheet were studied by the ANOVA analysis. ANN model provided better insight into the best conditions for process adjustment, making possible simultaneous optimization of multiple responses.