Colloquium announcement

Faculty of Engineering Technology

Department Design, Production and Management
Master programme Mechanical Engineering

As part of his / her master assignment

Snijder, H. (Henk)

will hold a speech entitled:

The role of powder ageing in the polymer sintering process

The role of powder ageing in the polymer sintering process - Snijder, H. (Henk)


In this master assignment, an experimental study on polyamide printing powder is performed. The additive manufacturing industry is printing more and more reliable products, knowing the quality of this printed product will be the key to delivering products on these requirements. The quality can deviate when printing with different states of powder, aged and virgin. For the experimental phase of this assignment, a simplified part of selective laser sintering is taken, the coalescence of two powder particles. To predict what the effect of aged powder is, different states of powders are taken to perform a hot stage microscopy experiment. The coalescence over time for these powders is compared and used by the multi scale mechanics group of the University of Twente to design a prediction model for this mechanism. The results of the experiments show degradation in the coalescence rate of the reused powders. The melt flow rate is decreased and for a large part this is contributed by post condensation of the material. The post condensation occurs in an earlier heating process of the powder and increases the molecular weight of the material, which is related to the viscosity and so the melt flow rate. This results in a recommendation for the additive manufacturing industry to adjust printing settings when using an amount of recycled powder, based on the level of degradation to gain a part with the best mechanical properties.