Mold Manufacturing 101: The Structure of the Mold

Mold Manufacturing 101: The Structure of the Mold

The mold manufacturing process for injection molding is called mold tooling. Most molds created for this purpose are constructed using steel, but can also be manufactured from aluminum.

No matter what the material, mold manufacturing is always a complex challenge considering that each mold comprises many different parts. This article will look at the mold’s structure and define each element.

Mold Base – The mold base comprises two or more metal plates called clamp plates. They are designed to hold all of the internal aspects of the mold securely between them.

Ejector Plate – The ejector plate is a moving part designed to lift the molded product out of the core.

Ejector Retainer Plate – The ejector retainer plate, more commonly known as the pin plate is a relatively thin plate of metal that fits over the ejector plate. It features holes for each ejector pin and acts as a locator for them.

“B” Plate – The “B” plate is designed to support the core of the mold as the “A” plate closes down on it.

“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 exterior shape of the part. This cavity can be placed in either the “B” plate or a plate, most commonly, in the “A” plate.

Mold Core – The mold core forms the interior of the final part. Similar to the cavity, the mold core can be found on either A or B plates.

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