Quick Cure Long-Shelf-Life Liquid Shim

The Navy and the Air Force currently use epoxy liquid shim materials for aircraft assembly. The two-part epoxy is mixed just prior to the application on airframe components during assembly. However this method is time consuming as excessive labor isrequired to support mixing, application and cleanup of the excess liquid shim material. This particular process has historically been a schedule driver in the F/A-18 E/F as two part liquid shim materials typically require eight hours or more prior tobeing able to perform the next assembly process. With the aggressive production rates proposed for the JSF program, optimizing manufacturing throughput is of paramount concern, which means reworking liquid shim practices. In support of this, the Navy islooking for innovative material approaches creating a quick cure (less than two hours), long working life (greater than one hour), and a room temperature shelf life exceeding one year. New shim materials should also remove the liquid shim process from thecritical assembly path. Under the proposed program METSS will evaluate single-component anaerobic-curing liquid shim compositions that will eliminate the need for mixing components, provide the required working time for parts assembly, and fully curewithin two hours or less. The proposed technology can be rapidly commercialized, thereby offering the Navy potential for a near-term solution to this critical production problem.