Modelling the filling behavior of micro structured plastic optical components

In the case of micro structured and freeform optics, such as Fresnel lenses, the challenges related to the filling of the samples address to formation of weld lines, cavity balance and mostly full replication of the part and its surface features. Even though simulation and modelling can help predict such errors, when dealing with micro structured components the multi-scale requirements of the problem become a challenge. Not only the model definition, but also more practical aspects, as model validation and the definition of the boundary conditions as meshing are time consuming, complex but necessary steps. In this research, modelling of the filling behavior of a micro structured optical component is performed and validated comparing Injection Molding simulation with measured Injection Molded parts. The adoption of different polymer dosages addresses the investigation on “short shots”, in this way the filling of the part could be investigated at different injection instances. The comparison encompasses both micro- and meso- scale quantities, such as the injection pressure measured at the screw, the part mass, and the height of the micro features. The results show that the adopted modelling solution is in accordance with the experimental results at both the geometrical scales.