Flow analysis of injection-moulded parts with cylindrical microfeatures

Injection moulding a macro-sized plastic part with microfeatures involves multi-dimensional flow and heat transfer behaviours, because there is a substantial difference between the dimensions of macro-sized part and its micro-sized features. How to effectively increase the filling distance of the microfeatures in a macro-sized part is a big challenge. In this study, a method combining both numerical simulation and analytical solution was employed to analyse the flow and the heat transfer behaviours of injection-moulded parts with cylindrical microfeatures. First, finite element and finite difference methods were used to simulate the filling process in the macrocavity based on a generalized Hele–Shaw theory. As a result, the pressure profiles at the entrance of the microfeatures were obtained. Then, the effects of the mould temperature, the injection speed, the dimension of microfeature, and the heat transfer coefficient on the filling distance in the microfeatures were investigated by a non-isothermal analytic method.