Speaker
Description
In hybrid injection moulds, the mould cavity in which a polymer product is shaped consists of nonmetallic inserts produced by a rapid manufacturing method such as AM. A promising AM material currently investigated in our group is PA11 processed by MultiJet Fusion (MJF). The material choice is relevant as it largely influences injection parameters and final product properties, due to the impact of thermal, mechanical and thermomechanical property variations. For instance, the thermal diffusivity of MJF PA11 is nearly 20 times lower compared to conventional mould steel, which results in a different cooling behaviour of the melt in the cavity, causing a different flow pattern during filling and longer cooling times before part ejection [1].
In the present contribution, an in depth study on the different material properties of the mould inserts and the final produced part morphology is conducted by performing injection moulding tests and simulations in which the material characterization results are utilized. Then the macroscopic part properties are linked to the morphology and processing parameters to compare hybrid with conventional systems. Both different flow patterns and extended cooling times lead to a final part morphology which deviates from parts manufactured in conventional steel moulds. As for processing, the difference in the flow pattern results in lower injection pressures which go up to only 45% of the pressure required to fill a steel mould with for instance polypropylene (PP). Different injection moulding settings such as injection velocities, melt temperatures and closed cooling times should therefore be altered for the production of specimens moulded in AM and steel mould inserts. Furthermore, a lower material strength for AM inserts results in a shorter lifetime of the mould insert and possible dimensional deviation between the parts due to compressive deformation and wear.
1. Fernandez et al. Plast. Rubber. Comp. 2020 accepted
| Speaker Country | België |
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