Effects of material and processing conditions on powder-binder separation using the Taguchi method

Abstract

The effects of material and processing conditions—powder size, injection temperature, initial powder volume fraction, and shear rate—on powder-binder separation in powder injection molding were investigated. A minimum set of experiments were performed based on the Taguchi method. The non-Newtonian viscosity model was employed to describe the rheological behavior of the feedstock. The critical solid loadings for the different powder sizes were determined by torque rheometry experiments. All other parameters for the viscosity model for the different powder sizes were obtained by capillary rheometry and linear fitting. The powder volume fractions along the radial direction of the polished surface were measured by image processing, based on the intensity difference between the powder and binder. The powder distribution profile was determined by a mean residual method. Powder-binder separation under the different processing and material conditions were quantitatively calculated by the definition of Variation. Finally, the effects of powder size, injection temperature, initial powder volume fraction, and shear rate were analyzed by the Taguchi method. Furthermore, the results of the Taguchi analysis were verified by additional experiments.