On the Influence of Thermal Histories within Part Cakes on the Polymer Laser Sintering Process

Polymer Laser Sintering (LS) is one of the most used Additive Manufacturing (AM) technologies for the tool-less production of polymer parts. The raw material is a polymer powder which is melted layerwise by the use of laser energy. Especially for the production of single parts, small series, individualized and complex structures, the technology is yet established in few branches. However, inhomogeneous and hardly controllable thermal effects during manufacturing limit the build reproducibility. The present work focuses on temperatures within so-called part cakes, their time dependency and their influence on process quality. Therefore, a temperature measurement system is implemented into a commercial laser sintering machine. Based on the experimental data a model to simulate heat transfer within part cakes is set up. Individual thermal histories during processing are successfully correlated with position dependent powder ageing effects. Another focus is on the analysis of a recycling optimized material. First results of correlations between thermal histories and part properties are shown in order to provide an outlook to further research. The data and knowledge gained through this work can be used to understand thermal effects in greater depth and to increase the process quality via optimizations.