Compression Molding

Molding composite structures under pressure.

Compression molding is a closed-mold composite manufacturing process that uses matched metal molds with the application of external pressure. In the compression molding process, an engineered composite layup is placed in the open mold cavity, the mold is closed, and consolidating force is applied. The pressure remains on the mold throughout the cure cycle, which usually occurs in an oven. The combination of heat and pressure produces a composite part with low void content and high fiber volume fraction—a near net shape finished component. Compression molding often yields composite parts that have the optimal mechanical properties possible from the particular combination of constituent materials.

An efficient production system.

This type of molding process is an appropriate fabrication system for producing uniform quantities of complex, high-strength composite structures of carbon fiber, aramid fiber or fiberglass. Compression molding allows for the manufacturing of intricate components with features, such as holes, that would otherwise have to be machined post-mold. The technique produces a highly integral composite structure, with fewer knit lines and less fiber-length degradation than injection molding.

Compression molding is versatile in application.

ACI produces many of its prosthetics, bicycle components and other complex geometries using this molding method. Compression molding, in addition to filament winding, lay-up and reaction injection molding processes, allows Advanced Composites Inc. to be almost unlimited in our ability to produce carbon, fiberglass and aramid composite structures for all applications.

A process that demands skill.

The system requires a high level of proficiency: placing the compound into the mold is fairly easy, but orienting the various layers of fiber correctly requires extensive training and experience. To this end, an Advanced Composites technician must apprentice under an experienced compression molder for several months, and demonstrate expertise in the various stages of the process before before becoming a compression molding technician. Even then, initially, novice compression molding technicians must operate under their instructors’ supervision until mastery has been sufficiently demonstrated.