Combined model for prediction of viscosity of powder injection moulding mixes

The rheology of powder injection moulding (PIM) mixes has been analysed in literature normally as a variation of the viscosity with independent parameters such as shear rate, temperature, binder/powder content, etc. A generalised equation incorporating all these parameters for the prediction of viscosity of PIM mixes is proposed in this paper. In order to validate the model, the viscosities of a few PIM mixes with ceramic powders and polymer-wax based binder systems were measured by capillary rheometry at various shear rates, temperatures, and binder contents. The experimental viscosity data shows excellent correlation with the proposed combined equation. The digitised data from literature also validated the model with good correlations. The model facilitates the estimation of critical binder volume concentration of the powder in the mix if the viscosity data is known.