The Influence of Grain Size Distribution of PA12 on Key Steps of the Polymer Laser Sintering Process
As the industry pushes for higher resolution laser sintering, finer and finer powders are required. Yet, this also changes the way powders behave during the process. In this project, the influence of finer particles on the dosing and coating process during laser sintering is being investigated. PA12 laser sintering powder without flow additives was sieved to four fractions with grain sizes with a d50 of 42, 54, 61 and 66 µm. These fractions were characterized regarding powder flowability by FT4 powder rheometer. The dosing and coating behavior of these fractions was tested in separate experiments on an EOS P395, where the coating experiments were performed at both RT and 175°C. Furthermore, test jobs were built with the different powder fractions. The larger portion of fines in the finest fraction dominated the powder properties and led to significantly worse powder behavior during the dosing and coating steps, as predicted by analytical measurements.