The hinge is the lynchpin of the mold and ensures each opening and closing is exactly the same no matter what type of machine it is on.
Like conventional molds, book molds may have taper locks to maintain alignment between both halves to avoid shifting. A tapered sprue bushing is located on the top of the mold so that, when the mold is opened, the sprue and runner will remain in the bottom half.
Ejectors are installed in the bottom half to lift out finished parts along with the sprue and runner, so multiple cavities are often well-suited for book molds. A handle is often mounted on the top half for easy opening, which can be done manually by the press operator or with a stationary ramp.
One service that is best used with book molds is overmolding. Overmolding is often confused with insert molding because it is performed on the same injection-molding machines. Overmolding is a subset of insert molding. All overmolding is insert molding, but it does not go both ways.
The term “insert molding” is often used when a pre-produced part is inserted into a mold and receives a mold around it. Overmolding is a similar process but is typically used when a part needs a second operation over the initial insert molding. It is still an insert-molded product, but the process is referred to as overmolding. Overmolding is also commonly referred to as “injection molding with a second operation,” or “insert molding with an overmolded sequence.”
The manufacturing process should always be at the forefront of a medical device engineer’s mind as manufacturing costs quickly rise with the complexity of each part. The best way to keep manufacturing efforts efficient and affordable is to find a capable vertical molding manufacturer to help through the entire process.
John Schmitz is president of Aberdeen Technologies (Carol Stream, Ill.), which provides plastic injection molding and mold tooling solutions to the largest medical device companies in the world. The company has been an insert molding provider for more than 25 years.