Numerical simulation of flow and thermal behaviour of polymer under microinjection moulding process: role of the thermal joint model at the mould–melt interface

This paper suggests an original numerical investigation through a two-phase filling-stage model of microinjection moulding (μIM) of thermoplastics. An unsymmetrical stepped-part decreasing thickness was considered to perform our modelling attempts. The transient equations of mass, momentum, energy conservation, and crystallization kinetics are solved simultaneously using the Finite Element Method (FEM). Flow front advancement is tracked through the Level-set method (LSM), employing the penalty approach to deal with the mass loss problems. The significant role of the interfacial thermal contact resistance ( TCR ) is introduced by the thermal joint resistances approach to predict the strenuous heat transfer phenomenon along the melt–mould interface, with the presence of gap conductance. The numerical code predicted the V-shapes of the flow Fountain effect and the distinguishing flow marks due to the trapped air between the melt front and the mould. The high accuracy of the thermal joint interfacial heat transfer ( h tc ) model and the consideration of the micro-scale features are necessary for capturing such relevant details. Model validation was performed using simulation of predicted spherulite diameters, shear rates, and layer thickness measurements. Aspects of the present work are beyond the capability of the current commercial software.