Combining 3D printing and injection moulding for the fabrication of polymer micro-components with internal hollow features

Abstract

There is a need to cost-effectively produce polymer components with meso/micro-scale internal geometries with high replication accuracy without the use of post-processing steps. A possible process chain to produce such polymer components with internal hollow features is by combining the 3D printing (3DP) and micro-injection moulding (MIM) processes. To date, no studies were carried out to explore the feasibility of such a process chain. Consequently, this experimental study investigated the use of the 3DP lost-cores that are over-moulded using the MIM process. The first step involved the production of lost-core from a soluble polymer material where three different materials were studied: two filament-based materials (Xioneer VXL130 and AquaSys180) and one resin-based material (IM-HDT-WS). The filament-based materials were printed on an Ultimaker S5 (filament fused fabrication) and the resin-based material was printed using an Asiga Max X27 (digital light processing). In the second step, the lost core was then over-moulded with polymethyl methacrylate (PMMA) using the MIM process. After demoulding, the internal core was then dissolved using the respective dissolution method of each material to achieve a part with meso/micro scale internal features. Investigations carried out at the different stages of the process chain revealed that the best dimensional accuracy was achieved when using the IM-HDT-WS material in the 3DP of the lost-cores and their subsequent over-moulding to form the case study part internal geometry. In particular, the dimensional analysis of the replicated IM-HDT-WS lost-core geometries onto the over-moulded PMMA revealed a difference of 0% in diameter and − 3.17% in bifurcation angle of the Y1.6 channel and a difference of + 4.88% in diameter and + 11.48% in bifurcation angle of the Y0.8 channels when compared to the respective 3DP core dimensional values prior to encapsulation. However, dissolution tests revealed that the filament-based material, the Xioneer VXL130, achieved a dissolution rate of 3.5 and 4.5 h for the Y1.6 and Y0.8 channel, respectively, which was marginally faster than that of the IM-HDT-WS.