Investigation on selective laser sintering of PA12: dimensional accuracy and mechanical performance

Selective laser sintering (SLS) has passed other techniques, thanks to its high print resolution, its ability to print microscale geometries without any additional support, its surface quality and its long-term thermal stability. However, despite the many advantages of SLS compared to fusion deposition modelling, there are still today some limitations on the materials to be printed. A limit critical from an industrial point of view is the aging of PA12 powder, i.e. the degradation of its physical and chemical performances, due to the high temperatures and the long printing cycles, thus involving a decrease of the mechanical properties of the printed parts. The purpose of this study was to charaterize mechanically and dimensionally specimens printed in PA12 through SLS by means of virgin or aged powder, i.e. powder just used for five printing cycles.

To achieve this aim, a set of specimens were designed, built, measured and mechanically tested; the obtained results were put into relationship with the values of the process parameters used to print them. Statistical tools to design the experiments and to analyse the obtained results were used.

The results show that the SLS process carried out through a Sintratec machine on PA12 powder has a good repeatability. To obtain the best dimensional and mechanical performances, it is needed to use virgin powder and place the part in the central zone of the printing area.

There are no scientific articles dealing with the influence of both the aging of the powder and the manufacturing parameters on the dimensional and mechanical characterization of specimens printed with SLS technique in PA12.