Impact of initial surface parameters on the final quality of laser micro-polished surfaces

Laser micro-polishing (L\u3bcP) is a new laser-based microfabrication technology for improving surface quality during a finishing operation and for producing parts and surfaces with near-optical surface quality. The L\u3bcP process uses low power laser energy to melt a thin layer of material on the previously machined surface. The polishing effect is achieved as the molten material in the laser-material interaction zone flows from the elevated regions to the local minimum due to surface tension. This flow of molten material then forms a thin ultra-smooth layer on the top surface. The L\u3bcP is a complex thermo-dynamic process where the melting, flow and redistribution of molten material is significantly influenced by a variety of process parameters related to the laser, the travel motions and the material. The goal of this study is to analyze the impact of initial surface parameters on the final surface quality. Ball-end micromilling was used for preparing initial surface of samples from H13 tool steel that were polished using a Q-switched Nd:YAG laser. The height and width of micromilled scallops (waviness) were identified as dominant parameter affecting the quality of the L\u3bcPed surface. By adjusting process parameters, the Ra value of a surface, having a waviness period of 33 \u3bcm and a peak-to-valley value of 5.9 \u3bcm, was reduced from 499 nm to 301 nm, improving the final surface quality by 39.7%.Peer reviewed: YesNRC publication: Ye