Rheological investigation and injection optimization of Fe–2Ni–2Cu feedstock for metal injection molding process

Abstract

In this study, rheological behavior and optimized injection parameters for Fe–2Ni–2Cu feedstock in the metal injection molding process were investigated using the capillary and Taguchi methods. For this purpose, the critical solids loading obtained for the feedstock by analyzing various solids loading (56–64 vol%). In the next step, fundamental rheological characteristics of a homogenized feedstock, including flow behavior index (n), flow activation energy (E), and general moldability index (αstv), were studied. Optimization of the most important injection parameters, including injection speed, injection temperature, mold temperature, and holding pressure, was conducted applying the Taguchi method. According to the results of experiments, injection speed plays a significant role in increasing the density and flexural strength. Also, there are optimum points for injection temperature and mold temperature, while holding pressure does not significantly influence the density and flexural strength. Satisfying results have been shown in green density and flexural strength after the verification test. Rheological behavior analysis showed 60 vol% as critical solids loading, while the proper solids loading considered to be 58 vol% in order to make an easier flow during the injection for the feedstock. The flow behavior index of developed feedstock indicates the shear rate sensitivity was desirable since it shows less than one value. Also, flow activation energy, which shows the feedstock sensitivity to the temperature changes, came out to be 78.138 kJ/mol. Finally, The general moldability index was calculated to be 3.1302E-06 Pa−1 K−1 by using these parameters.