Aging Dynamics in Polymer Powder Bed Fusion Systems: The Case of Selective Laser Sintering

Additive Manufacturing (AM), is an advanced production method for layer by layer fabrication, offering a paradigm shift in manufacturing. However, the sustainability of AM processes is poor, particularly as suppliers recommend reusing 50%-70% of reprocessed powder, contributing to significant material disposal.
To explore the possibility of fully reusing the polymeric material, we conduct a comprehensive characterisation of the powder particulates, in combination with analysis of the final prints. Utilizing optical and scanning electron microscopes, we statistically evaluate the size, morphology, and shape of the particles. Furthermore, tensile strength and deformation of printed bars is evaluated, showcasing the impact of aging on the print properties. The findings reveal that consecutive reuse of used powder significantly influences dimensional accuracy of the printed parts, as we detect increased relative value of shrinkage of 30.63 % after six printing iterations, absolute shrinkage increase by 0.98%, which is significant considering the standard shrinkage for the material used is 3.2%. Additionally, parts printed with reused material exhibit a slight increase in elongation at yield and an unexpected rise in tensile strength. Significant agglomeration of small particles is observed in the aged powder, especially ones less than 10 µm, not found in the virgin powder. These results contribute to a better understanding of the issues related to reusing aged material and offer valuable insights for mitigating the environmental impact associated with material disposal in AM.