Effect of stearic acid on rheological properties of 316L feedstock for metal injection moulding

Abstract

Stearic acid (SA) was used as an additive in the process of metal injection moulding (MIM). It was added to the wax/polymer mixture in order to modify the powder wetting, mould lubrication, mixture viscosity, residual stress and debinding behaviour. In this study, the effect of SA in feedstock formulation on mixing torque and rheological properties was investigated. Further, it's correlation on the as-moulded and as-debound parts behaviour was also investigated. The results showed that addition of SA significantly reduced the mixing torque value and viscosity which correspond to decreasing in inter-particle friction. As a result, injection moulding could be carried out at a lower temperature to achieve sound moulded parts and increased the removal rate of binder during solvent extraction process. However, it seemed that increasing the SA had a little negative effect on the as-moulded density. © 2012 Penerbit UTM Press.