PULSED LASER MICRO POLISHING: AN ANALYTICAL METHOD FOR PREDICTING SURFACE FINISH

This project is focused on developing physics based models to predict the outcome of pulsed laser micro polishing (PL mu P). Perry et al. [1-3] have modeled PL mu P as oscillations of capillary waves with damping resulting from the forces of surface tension and viscosity. They have proposed a critical spatial frequency, f(cr), above which a significant reduction in the amplitude of the spatial Fourier components is expected. The current work extends the concept of critical spatial frequency to the prediction of the spatial frequency content and average surface roughness after polishing, given the features of the original surface, the material properties, and laser parameters used for PL mu P. The proposed prediction methodology was tested using PL mu P results for Nickel, Ti6Al4V, and stainless steel 316L with initial average surface roughnesses from 70 nm to 190 nm. The predicted average surface roughnesses were within 10% to 15% of the values measured on the polished surfaces. The results show that the critical frequency continues to be a useful predictor of polishing results in the spatial frequency domain. The laser processing parameters, as represented by the critical frequency and the initial surface texture therefore can be used to predict the final surface roughness before actually implementing PL mu P.