Process Description
Open Molding is the most flexible of all composite fabrication processes. Part size and design options are virtually limitless for open molded parts. Typically, the open molding process is used for very complex parts that cannot be produced in more automated processes, or for parts that are produced in low volumes and cannot justify the higher mold costs of the automated processes. Mold turn-over is limited, but with skilled operators, good production rates and consistent quality are obtained. The open mold process frequently utilizes a surface coating called a gelcoat or topcoat. The gelcoat is applied directly to the mold using a spray process which results in a high quality durable surface. After the coating is applied, the back-up reinforcement and binder resin is applied, either by spray or manual application. Entrapped air is removed from the resin/reinforcement mixtures, and additional layers of laminate are added to build thickness and strength as desired. In addition to the reinforcement, low density core materials such as balsa wood, foam, or honeycomb can be added to stiffen the laminate without adding significant weight.