Characterization of Stainless Steel 316L Feedstock for Metal Injection Molding (MIM) Using Waste Polystyrene and Palm Kernel Oil Binder System

Abstract

This paper presents the homogeneity characterisation of MIM feedstock consisting Stainless steel alloy (316 L) powder mix with binder 60wt% of waste polystyrene and 40wt% palm kernel oil. It is one of a critical step that must be conducted in MIM process in order to have a feedstock that is homogeneous and moldable. Water atomised Stainless Steel powder was mixed with the newly developed binder system in a Brabender Plastograph EC rotary mixer. Several tests were performed to assess the homogeneity of the feedstock that was produced at 60 vol % powder loading . The 60 vol.% was chosen because the Critical Powder Volume Concentration (CPVC) of the Powder was found to be 64.8 vol.%. The tests conducted were feedstock density, binder burn-out, rheology and SEM morphology observation. Rheological results exhibited pseudoplastic or shear thinning flow behavior, where its viscosity decreased with increasing shear rate. The feedstock viscosity also decreased with increasing temperature and was found to be suitable for molding. From all the tests conducted, it was found that the feedstock shows good homogeneity and suitable for subsequent processes in MIM.