Closed molding is based on certain forms of physical enclosures to fabricate composite materials without atmospheric exposure. There are a wide variety of methods employing different ways of constriction, shaping, wrapping, or chemical conversion. It consists of four steps:
Assembly of raw materials and (inside) molding system
Closing of mold
Curing/hardening of materials
Opening of mold and removal of the final part.
Closed molding processes enable manufacturers to make precision parts faster and more consistently, with less waste. Usually automated with special equipment, they are perfectly suited for large plants that produce huge volumes of material—up to 500,000 parts a year.
Finished parts have a better surface finish, reducing the need for post-work. These molding processes tend to require higher capital investment in tooling and equipment.
Because the resin is handled in a closed mold system, there are significantly fewer emissions reducing the need for worker protective clothing and other PPE (personal protective equipment).
Compared to open mold processes, closed mold technologies offer such advantages as:
Reduced waste and emissions
Cleaner, healthier environment
Lower material/disposal costs
Greater consistency and repeatability
Reduced cycle times
Less operator-dependent and lower labor costs.
Require fewer molds.