Experimental and numerical analysis of the selective laser sintering (SLS) of PA12 and PEKK semi-crystalline polymers

•In the SLS process and more globally in additive manufacturing processes, there is a lack of global understanding and experimental data concerning either the laser irradiation, or the real temperature profiles carried out during the process, or the influence of powder properties that conduce to an optimum densification of the material.•Our paper on selective laser sintering of polymers is original first because of the dual experimental-numerical approach that we have implemented, which has necessitated the development and use of dedicated diagnostics (novel SLS set-up (Figs. 2 and 3), transmission measurements (Fig. 6), thermal measurements), together with the implementation of a specific finite element thermal model (Section 3.3).•This approach has allowed us to estimate numerically thermal cycles T=f(t) and optimal process windows for the selective laser sintering (SLS) of two polymers (PA12 and PEKK). With this method, we could establish the specificity of each polymer under laser irradiation (for instance, PEKK needs more time to densify), predict fusion depths and provide order of magnitude for maximum temperatures, cooling rates or degradation thresholds.•The numerical approach was also used for addressing more technical SLS process issues, like for instance how to maintain a high temperature level at the surface of the powder bed during powder layer spreading. This was done using numerical abacus (Fig. 14) to avoid crystallization during spreading.•To conclude, we think that the combination of experiments and rather simplified thermal calculation provides helpful information for optimizing and understanding the SLS process, which could not have been easily obtained without the use of an opened and instrumented SLS set-up. A dual experimental-numerical approach was carried out to estimate thermal cycles and resulting fusion depths obtained during the selective laser sintering (SLS) of two polymers: PA12 and PEKK. The validation of thermal cycles was obtained by considering fusion depths on single layers for different experimental conditions and temperature measurements with IR thermal camera. It was shown that a simple Beer–Lambert's heat deposit equation incorporating an extinction coefficient determined experimentally and an efficiency ratio including both laser absorption and diffusion in the powder bed were sufficient for determining accurately fusion depths, and heat cycles for the two polymers. This allowed determining optimum process conditio