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

Highlights: • The surface quality was greatly improved after post-processing. • The un-melted powder layer caused by selective laser sintering (SLS) was effectively removed. • The polished surface showed a better tribology performance. • No obvious chemical changes were induced on the sub-surface level within 10 μm. 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 15 μm Ra to 2.85 μm Ra and 0.89 μm 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 10 μm by the post-processes.