Ursachen für eine mangelnde Reproduzierbarkeit beim Laser-Sintern von Kunststoffbauteilen

Abstract

In the last few years laser sintering has been increasingly established as a manufacturing technique for small series production of plastic parts. However, the part quality oftentimes still does not meet the requirements due to warpage or poor reproducibility of part properties. One reason for this is the inhomogeneous temperature guiding while running the process. Significant local differences in the temperature-time-characteristic result from an inhomogeneous temperature distribution on the powder bed surface as well as from differences in cooling rates. Fundamental analyses on these effects have still to be done. Therefore, within the analyses presented here the reproducibility of different laser sintering machines should be studied in matters of the mechanical properties, the part’s density as well as the part’s accuracy. Additionally these results should be correlated to local temperature and cooling conditions in the powder bed. Thermal imaging is used to characterize the temperature distribution on powder bed’s surface, while the local cooling conditions within the powder bed are measured by special temperature radio sensors. In a further step the determined temperature and cooling conditions are correlated with position dependant analyses on the part shrinkage. Finally optimization potentials for a new temperature guiding system are deducted in order to establish more homogeneous temperature and cooling conditions.