Performance characterisation of a micro-injection moulding machine and influence of operative conditions on the process simulation accuracy

The purpose of the present study is to assess the simulation accuracy when modelling the filling phase of the micro-injection moulding process and to highlight the importance of proper choice of the values assigned to the process parameters. The injection of a miniaturized tensile test specimen made of POM has been chosen as case study. Mould temperature (Tmould), melt temperature (Tmelt) and injection speed (Vinj) have been analysed in order to have a better comparison between simulation and experimentation when the resulting mass injected is observed. In particular, due to measurement errors of the sensors or delays of the machine response to a command, it is necessary to study the effects on the simulation results deriving from such deviations to obtain highly accurate results and improve the design of the mould. Firstly, the injected volume related to the plunger stroke is studied (short shots) and the new filling conditions to be implemented in the numerical model are defined consequently. The results show that the mass differences between simulation results and experimentation can be largely attributed to the differences between the nominal values and the values measured by the sensors for process parameters.