Material flow data for numerical simulation of powder injection molding

2nd International Conference on Rheology and Modeling of Materials

Duretek, I.^1,2 ; Holzer, C.^1

Department of Polymer Engineering and Science, Montanuniversitaet Leoben, Leoben, Austria^1

Polymer Competence Center Leoben GmbH, Leoben, Austria^2

关键词: 316 L stainless steel;    316L;    Commercial injections;    Highly filled polymers;    Net shape manufacturing;    Powder injection molding;    Rheological measurements;    simulation;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/790/1/012007/pdf
DOI  :  10.1088/1742-6596/790/1/012007

来源: IOP

【 摘 要 】

The powder injection molding (PIM) process is a cost efficient and important net-shape manufacturing process that is not completely understood. For the application of simulation programs for the powder injection molding process, apart from suitable physical models, exact material data and in particular knowledge of the flow behavior are essential in order to get precise numerical results. The flow processes of highly filled polymers are complex. Occurring effects are very hard to separate, like shear flow with yield stress, wall slip, elastic effects, etc. Furthermore, the occurrence of phase separation due to the multi-phase composition of compounds is quite probable. In this work, the flow behavior of a 316L stainless steel feedstock for powder injection molding was investigated. Additionally, the influence of pre-shearing on the flow behavior of PIM-feedstocks under practical conditions was examined and evaluated by a special PIM injection molding machine rheometer. In order to have a better understanding of key factors of PIM during the injection step, 3D non-isothermal numerical simulations were conducted with a commercial injection molding simulation software using experimental feedstock properties. The simulation results were compared with the experimental results. The mold filling studies amply illustrate the effect of mold temperature on the filling behavior during the mold filling stage. Moreover, the rheological measurements showed that at low shear rates no zero shear viscosity was observed, but instead the viscosity further increased strongly. This flow behavior could be described with the Cross-WLF approach with Herschel-Bulkley extension very well.