Improving the Accuracy of Rapid Tooling for Design Evaluation

Abstract

The inherent technical limitations of rapid prototyping systems have lead to the development and industrial application of rapid tooling techniques. These techniques allow prototypes to be manufactured in final materials by the final manufacturing process. Enhanced silicone moulding is one such process which offers a rapid, low cost route to the manufacture of prototype plastic components in a metal impregnated rubber mould. During the moulding cycle the mould deforms under the high pressures and temperatures experienced and components produced suffer significant tolerance deviations. The main contributing factors are local deformation due to injection pressure and global mould expansion due to mould heating. In order to understand the individual effects and interaction of these deformation mechanisms on the part a finite element model of the system is developed.

Independent simulations of each of these phenomena are developed and indicate that results can be achieved within this approach using existing technology. Ultimately these simulations provide valuable information, which will help in developing an understanding of the deformation mechanisms involved. Furthermore, they provide the basis for a strategy to combine the two results, compensate for mould deformation and allow rapid low-cost production of more accurate prototypes suitable for thorough design evaluation.