Rheological Analysis of Microminiature Powder Injection Molding (μPIM) Feedstock

Abstract

A rheological analysis has been performed to evaluate the characteristics and behaviors of Microminiature Powder Injection Molding (μPIM) feedstocks. The feedstocks comprised of 316L stainless steel powder and water-based binder components. Feedstocks formulations with powder loading of 59% to 63% were prepared and investigated. In these formulations, the binder system consists of 65% Polyethelena Glycol (PEG), 25% Polymethyl Methacrilate (PMMA) and 10% Cellulose Acetate Butyrate (CAB) based on the weight fraction. The influences of rheological behaviors such as flow activation energy (E), Power-Law exponent (n), viscosity (η) and temperature (T) of the SS316L/PEG/PMMA/CAB feedstocks are analyzed and discussed. Results show that all of the feedstocks exhibited the pseudo-plastic flow behavior. The homogenous feedstock at 61 vol. % demonstrated the most satisfactory rheological properties for μPIM with the lowest flow activation energy, Power-Law exponent, n < 1 and moderate viscosity values. It was chosen to perform the injection molding process. Micro components have been replicated successfully by using this selected feedstock.

Investigation of Rheological Behavior of Low Pressure Injection Molded Stainless Steel Feedstocks

“…Thus, value shows that all PGA feedstock have high pseudoplastic properties and facilitate the process of injection molding. These results are in agreement with the studies conducted by Li and Muhamad [20]. Figure 5 also shows the viscosity dependence of various feedstocks on temperature and it determines the value of activation energy .…”