Rheological investigation of a starch-based binder and feedstock for metal injection molding

This study investigates rheological characteristics of a new binder system based on tapioca starch for metal injection moulding (MIM) process. First in this work, a composition of starch and linear low density polyethylene (LLDPE) as a binder has been provided. Mixture of binder and 316L stainless steel metal powder has been used subsequently to prepare three types of feedstocks with 56, 57 and 58% vol. powder loading. Rheological analysis of the binder and the feedstocks has been accomplished by means of a capillary rheometer. Viscosity values for binders have been measured lower than 10 Pa.s meanwhile this parameter has been obtained less than 1000 Pa.s for feedstocks. It has been observed that binder and feedstocks possess pseudo-plastic flow behaviour which is one of the most crucial requirements in MIM process. Experiments in this study confirm that tapioca starch has the potential to be used as a binder for in MIM process