Laser drilling in ablation regime: Study of drilling velocity with decoupled Q-switch laser

Future generation of laser drilling processes for cooling systems in aeronautics couple ablation and percussion removal regimes. Percussion using ms pulse laser duration, produces deep holes with high productivity and ablation, with ns laser pulse duration, regime machines shape holes with high quality. Up to now, acousto-optic Q-switch Laser are mainly used for this micro-machining. However, energy/pulse duration/repetition rate are coupled not allowing a comprehensive approach of interaction mechanisms. In this paper, we explore laser drilling laser in ablation regime using an innovative laser from Trumpf compagny. This laser provides TEM00 laser beam with energy and pulse duration independent of repetition rate. So, drilling velocity has been measured as function of laser parameters. It saturates at high laser intensity and stays constant for repetition rate under 70 KHz. Results are discussed vs laser screening induced by plasma in half-confined geometry and residual particles produced by the ablation.