Assessing polymer powder flow for the application of laser sintering

A need exists for techniques to assess flow properties of powders intended for laser sintering (LS). Although several powder flow measurement techniques are available, the flowability of a powder is strongly dependent on the nature of the applied flow field and none of the currently availably techniques adopt the flow field of LS. Therefore, this paper proposes a new technique, which mimics the flow in an LS machine, allowing a more appropriate powder flow evaluation for this particular process. The set-up provides qualitative assessment of powder layer smoothness, as well as a quantitative determination of the packing density of the deposited layer. Measurements on PA12, spherical PS and PMMA, and cryogenically milled TPU powders demonstrate the set-up's capability to evaluate powder flow with regard to LS.