Design and application of actively controlled injection schemes for resin-transfer molding

Liquid composite molding (LCM) processes provide the potential for producing complex net-shape components with relatively simple hardware requirements. The physical complexity of these processes has motivated the development of numerical process simulations, addressing preform manufacture, mold filling, and resin cure. While these simulations have increased the scope of parts successfully manufactured, it is argued here that in order to bring these processes to their full potential, intelligent application of active-control technology should be applied. In this paper we investigate active control of resin transfer molding (RTM), focusing on mold filling. A fully automated flow-visualization testbed has been developed, integrating a multiple line injection system, flow-front sensors, and automated vent assemblies. A mold-filling case study is presented here, demonstrating a design methodology for actively controlled injection schemes. The resulting injection scheme is implemented experimentally, and is shown to eliminate dryspots in all cases. As increasingly complicated parts are addressed, it is imperative that well-defined design methodologies are developed, that can be easily applied to the widest variety of components. (C) 2001 Elsevier Science Ltd. All rights reserved.