Three plate mold
A three-plate mold is a type of mold used in injection molding that consists of three plates:
Clamping plate: Fixed to the stationary plate of the injection molding machine.
Fixed die: Fixed to the clamping plate, forming part of the mold cavity.
Stripper plate: Clamped between the clamping plate and the core plate, and movable.
In the injection molding process, the molten plastic is first injected between the core plate and the stripper plate. Then, the mold is closed, and the molten plastic is forced into the mold cavity. After the plastic has solidified, the mold is opened, and the stripper plate moves first, separating the molded part from the core plate—finally, the core plate moves, ejecting the molded part from the mold.
The main advantages of three-plate molds are:
Can produce molded parts with small sprues: Because of the stripper plate, the sprue can be placed anywhere on the molded part without worrying about the sprue vestige affecting the appearance of the molded part.
Can produce molded parts with complex shapes: Because the stripper plate is movable, it is possible to produce molded parts with complex shapes, such as undercuts or sidewall cores.
Disadvantages of Three-Plate Molds
The main disadvantages of three-plate molds are:
Complex structure and higher cost: The structure of a three-plate mold is more complex than that of a two-plate mold, so the cost is also higher.
Longer molding cycle: Because of the extra step of moving the stripper plate, the molding cycle of a three-plate mold is longer than that of a two-plate mold.
Applications of Three-Plate Molds
Three-plate molds are typically used in the following situations:
High appearance requirements for molded parts: When small sprues are required on molded parts.
Complex molded part shapes: When molded parts with undercuts or sidewall cores are required.
Thin-walled molded parts: When thin-walled molded parts are required.
