On the influence of inter-layer time and energy density on selected critical-to-quality properties of PA12 parts produced via laser sintering

Laser Sintering (LS) of polymers is an Additive Manufacturing technique progressively used to produce functional parts. However, LS parts still present a certain quality variability. Efficient consolidation of the polymeric powder, necessary to obtain a dense part, mainly depends on the viscosity of the molten polymer and on the time given for the polymer to coalesce. The polymer viscosity is a function of the temperature and, consequently, of the energy density (ED) input by the laser. The sintering time strongly depends on the surface area to be laser-scanned in each layer, which in turn is strongly related to the product complexity and the number of parts within one build. The aim of this work is to investigate how this thermo-temporal effect, influenced by the ED and the inter-layer time, influences the resulting LS PA12 part quality at both micro-level (e.g., porosity, crystallinity) and macro-level (e.g., dimensional accuracy, mechanical performance).