Precision replication of micro features using micro injection moulding: Process simulation and validation

Abstract

Commercial software for injection moulding is available to optimise the mould design for macroscale products, but such software cannot accurately simulate the moulding process and defects for micro features, which are critical for the performance of polymeric micro/nano devices. In the present work, essential micro features with an aspect ratio of 3:1 on a microfluidic flow cytometer chip were used as typical models to develop a feasible approach to describe the filling of the micro features using commercial simulation software. Factors including the heat transfer coefficient, venting, wall slip and freeze temperature that were critical for micro injection moulding but not of primary importance for conventional injection moulding were specifically investigated. Based on process monitoring and a series of experiments and validation, the insufficient filling of micro features was successfully predicted. The heat transfer coefficient showed a significant impact on the filling of micro features. Venting and wall slip were both critical in simulating the filling process. This paper provides a reasonable approach that can be used to predict defects when injection moulding micro features, while the simulation accuracy still needs to be further improved.