Effect of the micromoulding process conditions on polymer flow behavior within a variable thickness microcavity

Abstract

Fast time to market along with high level of automation and versatility made microinjection moulding, by far, a favorite technique for the mass production of microplastic components. In the microimpressions, very high shear rates develop, eventually leading to excessive shear heating and consequently to less predictable flow behaviour comparing to conventional injection moulding. In this study, the flow behaviour within a variable thickness microimpression is investigated by monitoring pertinent process parameters such as cavity temperature and pressure. A micromoulding insert with a variable thickness was designed, fabricated and instrumented with pressure and temperature sensors. Full factorial design of experiment (DOE) was carried out to optimize the filling of the microimpression. The study with acrylonitrile butadiene styrene (ABS) suggests that the mould temperature plays an important role in the microimpression filling regardless of its thickness. In addition, the microinjection moulding process was monitored in terms of the cavity pressure and temperature, enabling closer assessment of the polymer flow state in the microimpression.