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.

Abstract

The correct selection of a curing tool, to make Carbon Fiber composite (CFRP) parts, is key to the success of a project. The trend in the Aeronautical industry is the reduction of costs and structural weights. The required curing tools are getting bigger and complex, which is a challenge for the manufacturers of the parts and tools. The high temperature autoclave curing cycles present a serious drawback to the use of conventional tooling materials, which has forced the development of molds made of materials with a low coefficient of thermal expansion to solve the problems arising from the different behavior of parts and molds during cycles and to ensure the tight geometric tolerances required. INVAR 36 and CFRP material with high performance resin have become standards for the manufacture of molds. The objective of the study is the comparison of properties and performance of this type of materials, as well as an estimation of the costs associated with each one, with the aim of helping the selection of the most appropriate for use in an industrial environment of high production rates. The method used consisted in the compilation of the technical characteristics of the materials that affect the performance of the tools, as well as the results of research projects and experience of the behavior in service. In addition, a simulation of costs associated with the development, manufacture, putting into production and maintenance of the molds was carried out. The results allow to evaluate qualitatively the performance of the molds manufactured with these materials as well as to have basic guidelines for the correct evaluation of them.