Optimization of the femtosecond laser trepan drilling strategy on IN792 for improving hole geometrical characteristics and machining efficiency.

Drilling film cooling holes (FCHs) that meet the stringent quality standards was a challenging task in aeroengine component manufacturing. This study aims to enhance the geometrical quality characteristics, such as hole taper and circularity, in the course of laser trepan drilling (LTD) of a 0.68-mm-thick IN792 superalloy while maintaining high processing efficiency and laser utilization. The linear correlation between the number of feeding times and entrance diameter has been confirmed, indicating that the diameter increases proportionally with the feeding times. This provides a useful reference for precise control of hole drilling geometry. By optimizing the scanning path and appropriately reducing the number of nested circles, machining efficiency improved. In addition, a variety of hybrid optimization strategies have revealed that moderately increasing the number of single-layer scanning times and adjusting the number of feeding times are key factors in establishing a suitable hole reaming process to improve machining quality and precisely control geometry. Finally, EDS analysis proved that only a small amount of oxygen was enriched at the orifice after removing oxides via oxidative ablation. Additionally, there were no heat-affected zones, oxidation zones, or recast layers. [ABSTRACT FROM AUTHOR]