Replication of micro-feature using variety of polymer and commonly used mould at elevated temperature and pressure

Due to the functional dependency of micro-systems technologies on stringent dimensions, masses and tolerances, strict quality requirement is paramount for mass producing micro-parts for use in micro-devices. The consistency of components produced could vary as a result of significant effects of process parameters or process noise, thereby necessitating the urge for experimental studies to determine the best process combination that will produce a variant free component that will meet the dimension, mass and other parameters requirement of its application use. In this paper, the influence of some process parameters on replication of micro-feature is explored. Parts with micro-feature designed are moulded using polyethylene and polypropylene. Design of experiment (DoE) approach was applied to correlate the fabricated parts quality to the processing parameters. Two level, half factorial 8-run (2 ^4-1) experimental plan was used to investigate the effect of four process parameters of melt temperature, injection pressure, mould temperature and holding time on the replicated quality of the moulded parts, with part mass as output parameter to reflect variability. Of all the investigated process parameters, result of experiment indicated melt temperature and holding time as most statistical significant processing parameter for parts produced using polypropylene. While there are no statistically significant effects of process parameters for those parts produced using polyethylene, rather, variability is observed to have occurred as a result of process noise. Furthermore, the experiments show that variability in the response parameter during micro-injection moulding differs for different polymer. Therefore, appropriate polymer type should as well be made to match with suitable processing parameters so as to obtain quality replication of micro-feature when mass producing.