Investigation of a novel laser shock liquid flexible microforming process applied to embossing three-dimensional large area microarrays on metallic foils

摘要

This paper proposes a novel micro high-speed forming technique, laser shock liquid flexible embossing (LSLFE), that uses liquid shock wave induced by the laser energy to achieve elastic–plastic forming of parts, to emboss metallic foils into three-dimensional large area microarrays, and expand the range of liquid impact forming application to the field of microforming. In this study, the micro-die and liquid chamber are designed to investigate the effects of the workpiece thickness and laser energy on formability. Then, experiments are performed to demonstrate the deformation characteristics of pure copper foils with LSLFE process. The results show that the fabrication of microparts with microscale structures through LSLFE is feasible. The morphology and fitability of the formed part indicate that accurate shape and dimension replication can be achieved through this technique. Then, the influences of laser pulse energy and copper foil thickness on the deformation depth of the formed parts are investigated. The results show that the depth of the replicated features increases with laser energy rising and the workpiece thickness decreasing. Besides, surface quality investigations indicate that the roughness of the fabricated micro-die and the original workpiece, as well as the process method significantly influence surface quality of the formed parts. Nanoindentation tests show that the hardness of the formed parts along the cross-section increases in various degree after LSLFE. Finally, the thickness distributions are characterized by polishing the cross-section of the formed parts and the most significant necking of thickness occurs at the fillet location.