Temporally modulated laser power dynamic drilling strategy with comprehensive optimization of quality and efficiency

Abstract

Motivated by the need to comprehensively optimize the quality and efficiency of laser drilling, a dynamic drilling strategy wherein laser power is temporally modulated is proposed, the laser power of which increases with the number of pulses to match the dynamics of the drilling process. Taking nanosecond laser drilling as the specific research process, the proposed dynamic drilling strategy is successfully applied. A continuous hydrodynamic model is first established to reveal the mechanism and driving force of material removal. Subsequently, linear and hybrid power growth profiles are proposed to improve the driving force of melt ejection and evaporation intensity during the drilling process. By comparing the variations in crater depth, ablation rate, recoil pressure, and recast layer thickness with the number of pulses, the effect of dynamic drilling modes on the drilling process and micro-holes performances was revealed. Moreover, the effect of power growth rate on the dynamic drilling process and final micro-hole quality is discussed in detail to provide a basis for formulation and optimization of the power growth profile. Finally, an experiment using an aerospace Ni-based superalloy verifies the reliability of the dynamic drilling strategy and the material removal rate, taper, and recast layer thickness of the micro-holes are comprehensively optimized. The proposed dynamic drilling strategy provides an effective solution to the universal problems of micro-hole quality and efficiency in the field of laser drilling.