Evolution of Geometry and Surface Quality of Laser-Drilled Micro Holes by Electrochemical Post-Processing

Micro holes are critical structures of the components in industrial. Laser drilling can efficiently process micro holes, but defects such as recast layer and taper limit its wide applications in engineering. In this paper, electrochemical post-processing has been employed to improve both the surface quality and precision of the laser-drilled micro holes. The evolution of the surface quality and geometry of the laser-drilled micro holes during the electrochemical post-treatment process was studied. Simulation results showed that the diameter of laser-drilled micro holes increased, and the taper of the laser-drilled micro holes decreased with increasing processing time and voltage. Experiments were conducted to investigate the effects of different electrolysis parameters on the quality of holes. Results demonstrated that the diameter increased with the increase of processing time and voltage, and the taper decreased with the rise of processing time and decreased first and then increased with the increase of voltage. Micro holes with a diameter of 0.614 mm, a taper of 0.85°, a surface roughness of Ra 3.2 μm and free of recast layer were obtained with a voltage of 20 V, a pulse frequency of 20 kHz, a duty cycle of 60%, and an electrochemical post-processing time of 18 s.