A quantitative approach to assess high temperature flow properties of a PA 12 powder for laser sintering

In order to consider thermal conditions involved in laser sintering (LS), the effect of temperature on the flow properties of a polyamide 12 powder was assessed. Shear tests were carried out at temperatures from ambient up to values close to the melting temperature of the polymer. The measurement method provides quantitative descriptors of powder flowability. Experiments indicate that flowability significantly deteriorates when temperature rises and approaches a value of about 20 °C lower than the melting temperature. The spreading process may be hindered by natural agglomeration of the material. A simple analysis based on the extrapolation of the bulk flow properties at zero consolidation shows that agglomeration is excluded in the temperature range between 100 and 140 °C. This turns out to be the range in which it is known that the material can be used safely for LS applications.