On the performance of a viscoelastic constitutive model for micro injection moulding simulations

The numerical simulation of the injection moulding process involving microstructures presents several chal- lenges, mainly due to the surface effects that dominate the flow behaviour at the microscale. In this paper a new approach, which employs weld lines as flow markers, is used to evaluate whether the numerical codes that are normally used to sim- ulate the conventional injection moulding process, are suitable to characterize the melt flow patterns in the filling of micro features. The Cross-WLF viscous model and the Giesekus viscoelastic model were evaluated using 3D models of a micro part implemented in two different numerical codes. A micro cavity was designed in order to compare the results of numer- ical simulations and experiments. While the viscous simulations were found to be inappropriate for multi-scale structures, the accuracy of micro filling predictions was significantly improved by implementing a viscoelastic material model.