Surface quality improvement of selective laser sintered polyamide 12 by precision grinding and magnetic field-assisted finishing

Abstract

Surface quality is essential for additive manufactured components due to the growing demand in various industries. This paper presents an experimental and analytical study on post-processing of selective laser sintered Polyamide 12 (PA12), aiming at improving surface quality and clarifying interrelations between surface quality and process parameters. The effects of post-processes on surface and subsurface characteristics regarding material removal, surface morphology and roughness, hardness, tribology performance were quantitatively evaluated. The results show that after post-processing, the surface roughness of the PA12 components were reduced obviously from over 15μm Ra to 2.85μm Ra and 0.89μm Ra by precision grinding and magnetic field-assisted finishing (MFAF), respectively. The un-melted powder surface layer was effectively removed although the surface hardness was slightly reduced. The MFAF processed surface showed a better tribology performance represented by lower coefficient of fiction and higher wear resistance. Moreover, the results of laser Raman analysis and X-ray photoelectron spectroscopy (XPS) indicated that there were no obvious chemical changes induced on the sub-surface level within 10μm by the post-processes.