New technologies are being developed to meet the special problems encountered in molding precision parts from highly anisotropic composite materials comprised of advanced fibers and resin. Design considerations require many different ply orientations to fully utilize superior fiber mechanical properties. Coincident with their directional mechanical properties, composites exhibit a similar degree of anisotropy in other physical properties. Measured thermal coefficients of expansion for graphite/epoxy laminates are of −0.5 × 10−6 in/in/F parallel to the fiber axis and 39 × 10−6 in/in/F perpendicular to the fiber axis. Since composite parts are cured at elevated temperatures, this anisotropy produces appreciable residual stress as well as stability problems in dimensions of the finished part. Examples of these problems are presented. In addition to specific problem areas, the many aspects of achieving a true precision molding are reviewed. Specifically, the fabrication variables associated with resin and fiber selection, consolidation, and cure procedures are discussed.

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