The characterization of the hole-contour and plume ejection in the laser drilling with various inclination angles

The contours of the drilling-hole for the laser drilling at various inclination angles were investigated in this study. A simple model was proposed to estimate the drilling-hole shape and it was verified with experiments in pulsed laser drilling process. The contour dimensions of the drilling hole are significantly affected by laser power and inclination angle, and there is a good agreement between the simulation and measurement. Furthermore the laser induced plume on the graphite substrate heated by a Nd-YAG pulsed laser at various inclination angles was visualized experimentally. It can be found that the plume ejection is mainly normal to the substrate surface without the shielding gas.

► A model was proposed to estimate the drilling-hole shape on the inclined substrate.
► It was verified with experiments in pulsed laser drilling process.
► There is a similar tendency between the numerical and experimental results.
► The laser beam center is at the location of the maximum drilling depth.
► The plume ejection direction is perpendicular to the inclined substrate.