Research on process and mechanism of micro punching driven by laser-induced cavitation

In this paper, a method of micro-punching driven by combining laser-induced cavitation was proposed. By analysing the surface roughness and the morphology of copper foil punched by the process, the influences of key process parameters including laser energy, cavitation position and punching times on the punching workpiece were systematically studied. With the laser focus position changing from -1 mm to +3 mm, the maximum depth of punching copper foil pits gradually decreased from 118.10μm to 55.19μm, and the ablative degree of the pit bottom reduced gradually. Meanwhile, it is found by high speed camera that the plasma shock, collapse shock and micro-jet produced by laser induced cavitation are the main driven power sources for deformation. Finally, the process is optimized with laser focus position of +2 mm, laser energy of 10.1mJ and 5 laser pulses, the surface ablation could be completely avoided.