Simulation of surface roughness evolution of additively manufactured material fabricated by laser powder bed fusion and post-processed by burnishing

Abstract

Additively manufactured (AM) metal parts are usually post processed by mechanical surface finishing to attain desired surface roughness. Simulation of AM chain provides means to effectively optimize the final product's quality characteristics in the design stage. The present study developed theoretical models for simulation of surface topography and roughness of parts produced by the laser powder bed fusion (LPBF) process and their evolution after burnishing as post-treatment. The simulation algorithm has been integrated by combining principles of LPBF process, i.e., formation of the melt pool and kinematic of motion, as well as the fundamental theorem of multi-roller rotary burnishing process, i.e., Z-map approach and mechanic of elastic rebound of the surface. This simulation allows the surface topography and roughness to be controlled by adjusting both sequential processes' parameters in a short period with acceptable accuracy. To verify the simulation results, 316L stainless steel was fabricated by an EOS GmbH printing machine and then burnished under different processing conditions. 3D surface profile and surface roughness of as-printed material and those post-processed by burnishing were measured through microscopic examination and surface roughness measurement, respectively. The results obtained through comparison of confirmatory experiments and simulation model affirmed that the proposed approach is accurate enough to predict the surface topography and roughness of as-printed and post-treated samples. The proposed integrated simulation framework has been further utilized to identify how the parameters included in the chain of additive manufacturing and sequential post-processing contribute to achieving nanoscale surface finish in the design stage.