Simulation is commonly used to optimise mould design for complex 3D products, but it is particularly difficult to describe precisely the injection moulding process for microscale features. In the present project, a typical micro-sized feature, critical for a microfluidic flow cytometer chip, is used to develop a feasible approach to simulate the filling progress of micro features. Factors including heat transfer coefficient, venting, wall slip and freezing temperature are studied. Notably, the insufficient filling of micro features is predicted successfully, and the selected parameters are validated by two further configurations of microfluidic mould tool inserts. This project constitutes an important example of simulating the micro injection moulding process in the production of polymeric microscale devices and the development of mould tool inserts with micro-sized features.
- Difficult to capture the filling behaviour of polymer melt in micro-sized cavities
- Defects of micro features couldn’t be predicted using simulation when using default and normal parameters before a mould tool is manufactured
Moldex3D Designer BLM was used with specifically modified node seeding. Furthermore, real process conditions, actual machine responses, and physical phenomena including heat transfer coefficient, venting, wall slip and freezing temperature were all integrated into the analysis. This helped to ensure that the real problems of the filling of micro features can be predicted, thereby saving the cost that would otherwise be required to rectify these problems after manufacturing a mould tool.
- Successfully predicted the incomplete filling of micro-sized features
- Validated the effectiveness of proposed manufacturing solutions, such as variotherm injection moulding
- Evaluated alternative designs before production, saving time and money