Application of picosecond laser for polishing of AISI H13 tool steel sample prepared by micro milling

This paper explores the applicability of picosecond laser (ps) in laser micro polishing (L\u3bcP) of AISI H13 tool steel. The melting regime associated with this process was determined experimentally through the variation of the focal offset in order to attain a desired fluence level. To ensure the consistency and certainty of initial surface geometry, the surface was prepared through a micro milling operation with a step-over of 50 \u3bcm and scallop height of 2 \u3bcm. The L\u3bcP experiments were performed at 5 different fluence levels of the melting regime obtained through setting of the focal point at 5 different distances. The polishing performance was evaluated based on the distribution of line profiling average surface roughness (Ra) at various spatial wavelength intervals. Additional statistical metrics such as material ratio function and power spectral density function were also determined in order to establish the process parameters associated with best achievable surface finish. Finally, as a demonstration of the applicability of ps L\u3bcP process, a flat micro milled area was polished using optimum process parameters. This operation yielded in 68% surface quality improvement as quantified through the reduction of the areal topography surface roughness (Sa) from 0.53 urn to 0.17 \u3bcm.Peer reviewed: YesNRC publication: Ye