Comparative Assessment of the Laser-Induced Plasma Micromachining and the Ultrashort Pulsed Laser Ablation Processes

Abstract

The ultrashort pulsed laser ablation process is a well-established micromachining process and has been at the center of manufacturing research in the past decade. However, it has its own limitations, primarily due to the involvement of various material-specific laser and machining process parameters. The laser-induced plasma micromachining (LIP-MM) is a novel tool-less and multimaterial selective material removal type of micromachining process. In a manner similar to ultrashort pulsed laser ablation, it also removes material through an ultrashort pulsed laser beam. However, instead of direct laser–matter interaction, it uses the laser beam to generate plasma within a transparent dielectric media that facilitates material removal through plasma–matter interaction and thus circumvents some of the limitations associated with the ultrashort pulsed laser ablation process. This paper presents an experimental investigation on the comparative assessment of the capabilities of the two processes in the machining of microchannels in stainless steel. For this purpose, microchannels were machined by the two processes at similar pulse energy levels and feed-rate values. The comparative assessment was based on the geometric characteristics, material removal rate (MRR), heat-affected zone and shock-affected zone (HAZ, SAZ), and the range of machinable materials.