DME University

Why are Ejector Pins Important?

After a molded part is cooled, it must be ejected out and clear of the mold cavity. An ejector pin, sometimes called a knockout pin, is a device typically used for part ejection.

As a molded part cools it contracts an amount depending upon the shrink rate of the plastic resin used. A device called a core is used to make an internal shape in a part. Even with draft or taper on its sides, part removal from the core would not be practical without an ejection device.

This unit will cover some of the many styles, coatings, and hardening methods used for ejector pins.



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