ABSTRACT
Liquid composite molding (LCM) is a class of manufacturing processes used to produce polymer composite components and structures (materials consisting of high-strength fibers embedded in a polymer matrix). In any LCM process, a fibrous preform material is placed into a mold, and then the mold is closed and sealed to prevent leakage before a liquid resin is injected. The resin is introduced with either positive pressure or by drawing a vacuum (Advani and Sozer 2003). The most common LCM process that uses two-sided rigid tooling is called resin transfer molding (RTM). As seen in Figure 18.1a, the rigid tooling in RTM encompasses the fibers and compresses them to the desired fiber volume fraction. Then resin is injected through ports located in the rigid tooling to fill the empty spaces between the stationary fibers. Once the preform is fully wetted and the resin cures, the mold is opened and the finished part removed. The vacuum-assisted resin transfer molding (VARTM) process, shown in Figure 18.1b, uses only a single-sided tool, and the mold is sealed by enveloping the preform fabric with a nonrigid polymer film adhered to the tooling surface with a sealant tape. A vacuum is used to compact the preform and draw the resin into the mold from a reservoir at atmospheric pressure. Many variations of this process have been introduced to overcome the disadvantage of lengthy filling times, which is especially protracted when manufacturing large structures. The most favored
CONTENTS
Introduction Liquid Composite Molding and Vacuum Infusion Processes ....................................................................... 531 The VARTM Process ..........................................................................................533 Theory of Resin Infusion in VARTM ................................................................ 537 Process Automation and Control ...................................................................... 539 Current VARTM Applications and Future Developments............................540 References .............................................................................................................542
