Mold Making: The Structure Of The Mold

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Mold Making: The Structure Of The Mold

The plastic mold manufacturing process of injection molding is called mold processing. Most molds made for this purpose are made of steel, but they can also be made of aluminum.

No matter the material, mold-making is always a complex challenge considering that each mold contains many different parts. This article will look at the structure of the mold and define each element.

Formwork - A formwork consists of two or more metal plates, called plywood. They are designed to hold all the internal parts of the mold firmly between them.

Ejector Plate - The ejector plate is a moving part designed to remove the molded product from the core.

Ejector Mounting Plate - The ejector mounting plate, commonly called the needle plate, is a relatively thin metal plate that mounts to the ejector plate. Each thimble has holes and acts as a locator for them.

"B" Plate - The "B" plate is designed to support the core of the mold when the "A" plate is closed.

"A" Plate - The "A" plate closes on top of the "B" plate and receives the plastic resin from the machine.

Mold Cavity - The mold cavity is filled with plastic resin to form the final outer shape of the part. This cavity can be placed in the "B" plate or in one plate, most commonly in the "A" plate.

Core – The core forms the interior of the final part. Similar to cavities, cores can be found on either the A or B plate.

Sprue Bushing – The sprue bushing is placed inside the "A" plate and acts as a channel for the plastic resin to flow through and to the mold cavity and core.