3D printed RTM prototype-moulds

Abstract

In the present work the feasability of 3D printintg, more specifically the FDM (Fused Deposition Modeling) technology, to manufacture moulds of RTM in the phase of prototyping has been demonstrated. The upper part of the mould for a side-intrusion bar of a front door of a car has been manufactured, since the bottom mould is the original metallic. Printing of the mould took 104 hours and 3.8 kg of plastic were used. For the employed PLA, it has been established that up to 5 mm thick the translucency is sufficient to observe the resin flow pattern during injection. In order to increase the rigidity of the mold, different geometries of vertical reinforcements have been analyzed by means of finite element simulations. Finally, the honeycomb-like structure has been selected. At the stage previous to the injection, when the vacuum is made, the presence of the glass fiber preform reduces the displacements measured at different points on the mould. Additionally, the tightness has been good even without applying any kind of surface treatment. However, when the resin is injected the intrinsic stiffness of the mould has not been sufficient to limit displacements and to make a good piece. This has been solved by using a 30 mm thick methacrylate plate to stiffen the mould, which in turn allows the visualization of the flow through the mould.

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