Comprehensive in-mould state monitoring of Material Jetting additively manufactured and machined aluminium injection moulds

Abstract

The rapid evolution of additive manufacturing (AM) technologies is expected to revolutionize the injection moulding industry as well. AM technologies can be used to manufacture injection mould inserts. Several polymeric additive technologies like Material Jetting (including PolyJet), Material Extrusion (including Fused Deposition Modeling (FDM)) and Powder Bed Fusion (including Selective Laser Sintering (SLS)) can make mould inserts that are suitable for small series production. Metal inserts, made of steel or bronze can also be produced by Powder Bed Fusion (for example by Direct Metal Laser Sintering (DMLS)). These are comparable to their traditional, machined counterparts, regarding longevity and dimensional accuracy. In our study, we made inserts by Material Jetting (PolyJet) from an epoxy acrylate resin and compared its in-mould behaviour to a reference mould insert machined from aluminium. We measured the operational strains, cavity pressure and temperature distribution of the inserts. Operational strains exceeded 2 % in the case of the epoxy-acrylate insert. However, strains of the aluminium insert remained below 0.03 % for the aluminium insert under the same operational conditions. We set up correlational diagrams to numerically specify the load-deformation curve of the mould inserts. We also applied 3D scanning to measure the deformation of the inserts and injection moulded products alike. We found that scanning the injection moulded products yields more information about operational deformation of the inserts than scanning the inserts themselves.