This paper presents an interesting nanosecond (ns) laser-induced plasma deburring (LPD) effect (from microchannel sidewalls) discovered by the authors, which has been rarely reported before in the literature. Fast imagining study has been performed on plasma produced by ns laser ablation of the bottom of microchannels. It has been found that the plasma can effectively remove burrs from the sidewall of the channels, while on the other hand microscopic images taken in this study did not show any obvious size or shape change of the channel sidewall after LPD. LPD using a sacrifice plate has also been studied, where the plasma for deburring is generated by laser ablation of the sacrifice plate instead of the workpiece. The observed laser-induced plasma deburring effect has several potential advantages in practical micromanufacturing applications, such as high spatial resolution, noncontact and no tool wear, and less possibility of damaging or overmachining useful microfeatures when removing burrs from them. The fundamental mechanisms for the observed laser-induced plasma deburring effect still require lots of further work to completely understand, which may include mechanical breaking of burrs due to high kinetic energies carried by plasma and the associated shock wave, and/or thermal transport from plasma to burrs that may cause their heating and phase change, or other mechanisms.
Ultraviolet femtosecond and nanosecond laser ablation of silicon: Ablation efficiency and laser-induced plasma expansion