Advances in elastomeric tooling technology

Abstract

Among the modern technologies able to produce hollow composites components, vacuum bagging in an autoclave is the most widely used. It is very flexible, but also very labour-intensive. In addition, the high costs of its consumables and of equipment has to be considered. For these reasons, strong economic motivations exist to develop alternative technologies, such as that of the elastomeric tooling treated in the present article. This is based on the use of elastomeric mandrels which, when contained in closed metal tools, as a result of the larger thermal expansion of the elastomer provide the pressure needed for laminate compaction during the curing process. The production of hollow components is studied in this paper by means of analytical, numerical and experimental approaches. They allow us to evaluate the pressure exerted by the mandrel during the thermal expansion process as a function of both geometry and temperature. Analysis and comparison of the results demonstrate the need to design the mandrel accurately and characterize the elastomeric material, because even minimal errors during mandrel preparation induce pressures unsuited for the production of composite artefacts.