openmolding

Openmolding is a manufacturing process that involves shaping materials, often plastics or composites, within a mold that is not entirely enclosed. Unlike traditional closed-molding techniques where the mold is clamped shut, open molding leaves one or more surfaces of the mold exposed to the atmosphere. This exposure allows for easier access to the material being molded, which can be beneficial for certain applications.

The most common method within open molding is hand layup. In hand layup, layers of reinforcing material, such as fiberglass or carbon fiber, are placed into the mold. A liquid resin, often polyester or epoxy, is then applied with brushes or rollers to saturate the reinforcing fibers. This process is repeated until the desired thickness is achieved. Once the resin cures, the part is removed from the mold.

Open molding is generally a simpler and less expensive process compared to closed molding. It requires less sophisticated tooling, making it suitable for producing large or complex shapes, prototypes, or low-volume production runs. Applications for open molding include boat hulls, automotive body panels, wind turbine blades, and various custom fabrications. However, the open nature of the process can lead to a less precise finish, potential for voids, and emission of volatile organic compounds (VOCs), necessitating careful handling and ventilation. Variations exist, such as spray-up, where chopped fibers and resin are simultaneously sprayed into the mold.