Characterization of Polymer Powders for Selective Laser Sintering

Flowability and packing properties are essential for powder spreading and resulting part properties in powder bed fusion processes (PBF), such as selective laser sintering (SLS). In this contribution, powder requirements for SLS, structure-property relationships and appropriate methods for powder characterization are reviewed. Effects of particle size, particle shape and surface functionalization on flowability, packing density and tribo-charging will be discussed for commercial PA12 laser sintering powders (virgin vs. aged), polyolefin and polyester powders. The possibilities of dry particle coating as an efficient method to tailor powder flowability, bulk density and charging behavior are demonstrated. The capabilities of a Schulze ring shear tester, a powder tensile strength tester, a thermally controllable ring shear apparatus and a model experiment mimicking the powder spreading are discussed to assess SLS processability.Mechanical Engineerin