Mold Components

Components of an Injection Mold

So you've designed a product. You've gone through the RFQ process, sharing your CAD drawings with engineers who probably made even more tweaks. The part is going to be made of plastic using the injection molding process. But you've never made a plastic injected part before. There are a lot of new words and phrases being tossed around and you don't really know what they all mean. Runner Sprue? Water Baffle? Ejector Pin?

Is a tool the same thing as a mold? Why is mold spelled two ways (mold vs. mould)?

And how does the whole thing actually work?

No one would blame you for looking for a glossary of terms right about now. Fear not. Below, we break down the components of an injection mold in simple, easy-to-understand language. It even includes labeled cutaway drawings. I promise, if you didn't understand how an injection mold worked before, you will after reading this.

An injection mold is a tool comprised of a series of parts that allows molten plastic to be formed and cooled in such a way as to create a discrete part shape. A lot of mold parts,mold components are used in one set of mold, including ejector pin, guide post, guide bush, mold spring, stripper bolt, sprue bush, gate bush and etc.

DETAILED COMPONENTS

CLAMP PLATES

Liquified plastic is pushed through the nozzle of the barrel of the molding machine. The nozzle seats against a surface on the mold called the sprue bushing and locating ring, which help center the nozzle to the mold.

FEED SYSTEM

The sprue and runners can be reground (chopped up) and reused. They can be eliminated by using a hot runner system.

CAVITIES

Plastic is injected hot and is cooled by cooling channels that allow conduction to cool the part. Working fluid is typically water, although oil can be used in high temp applications.

GUIDE PILLARS/BUSHINGS

Parts are pushed off of the core using a series of pins or bars. These series are called the Ejector System.

EJECTOR PLATE SYSTEM