Characterisation of alumina feedstock with polyacetal and wax-polymer binder systems for micro powder injection moulding

Powder injection moulding (PIM) is a cost-effective technique for producing small, complex, precision parts in high volumes from powders. To have a good understanding of the PIM process and to provide the necessary data for simulation studies, detailed characterisation of the powder-polymer mixture (feedstock) is essential. In this paper, the characterisation of feedstocks consisting of alumina powder (median particle size of ~ 400 nm) with polymer/paraffin wax (Standard Mix) and polyacetal (Catamold AO-F, BASF) binder systems for micro powder injection moulding (µPIM) is reported. It was found that the Standard Mix had lower viscosity and heat capacity as well as greater pseudo-plasticity compared to the Catamold AO-F. However, the results from Moldflow simulations and scanning electron microscopy inferred that the Catamold AO-F filled the microcavities (50µm) more efficiently than the Standard Mix. In addition, the micro powder injection moulding of an alumina dental bracket was analysed using the Moldflow package following measurement of key feedstock material properties. A possible correlation was observed between the mould filling behaviour and the dimensional scatter of the sintered parts.

Characterisation of alumina feedstock with polyacetal and wax-polymer binder systems for micro powder injection moulding Articles