Improving surface finish in pulsed laser micro polishing using thermocapillary flow

Thermocapillary flows can be generated in pulsed laser micro polishing by using longer melt durations, significantly reducing surface roughness at the expense of creating residual high spatial frequency process features. However, polishing with short melt durations, with no thermocapillary flows, effectively smoothens high spatial frequency surface features. This paper presents a two-pass polishing process in which the first pass takes advantage of thermocapillary flows in significantly reducing the surface roughness, and the second pass removes the residual process features. Experimental results of polishing micro end milled Ti6Al4V surfaces are presented that indicate 72% improvement in average surface roughness.