The Influence of Pressure Dependent Viscosity on the Powder Injection Molding Process Simulation

Activity: Talk or presentation Oral presentation


Powder injection molding (PIM) is a manufacturing process for the series production of metal or ceramic parts. PIM is an alternative to machining and investment casting and an ideal fabrication process for manufacturing complex, functional components in large quantities and with high material requirements; widely applied in various industries and applications. The shaping phase is realized usinginjection molding. During the filling phase high injection rates are required to fill the cavity in the shortest possible time, thus resulting in relatively high injection pressures which leads to the compression of the free volume of polymer chains of the feedstock-binder component, therefore the viscosity will increase. With the help of the injection molding simulation it is possible already in the early phase of the development and construction to detect and avoid wrong design decisions. This can only be achieved if reliable and accurate rheological material data are available. The flow behavior of PIM-feedstocks depends on shear rate, temperature and pressure. However, the effect of pressure is often neglected.The aim of this work was to investigate the influence of pressure-dependent viscosity on the results of the powder injection molding process simulation. For this purpose,viscosity measurements of a commercial PIM-feedstock, Ti48Al, at different temperatures without counter pressure and different counter pressures were carried out by means of a high-pressurecapillary rheometer and a commercial counter pressure chamber. Furthermore, a sensitivity study was performed with the injection molding simulation software Autodesk Moldflow Insight 2019 by Autodesk Inc. to evaluate the importance of the pressure dependent viscosity on the predicted injection pressure required to fill a tensile test specimen mold. 4thInternational Conference on Rheology and Modeling of Materials37The measurement results clearly show the pressure and temperature dependence of the viscosity. An increase of the counter pressure from 0 to 250 bar results in aviscosity increase by approx. 2 times. The coefficient D3 in the Cross-WLF model, which is related to the polymer compressibility and the pressure influence on viscosity, respectively, was calculated and is approx. 9.7×10-7 K/Pa, which is a relatively high value. The importance of pressure dependent viscosity in the filling simulation of PIM was confirmed in the simulation.
Period8 Oct 2019
Event typeConference
LocationMiskolc-Lillafüred, HungaryShow on map
Degree of RecognitionInternational


  • Rheology
  • Viscosity
  • powder injection moulding