ejector system in injection molding

Ejector system in injection molding use to push the final samples out of the mold. They are used forcefully to eject the solid part out of the mold and are usually made of high-quality steel.

I. Basic construction of ejector system.

Picture above show basic construction of ejector system.

1. Return pin: It always pushes ejector system return with spring force.

2. Ejector stopper: It prevents impacted between core plate and ejector plate.

3. Stop pin: A stopper installed to keep an ejector plate horizontal or prevent the ejector plate from retreating too far and damaging a core adaptor plate.

4. Ejector pin: It will push samples out of the mold.

5. Ejector plate: Use to assemble ejector pin, return pin, ejector stopper. There are two ejector plates in the injection molding.

6. Sprue lock pin: When mold opening, runner will stick in sprue lock pin.

7. Spacer block: It will create distance between bottom plate and core plate. This distance use to assemble ejector system.

8. Ejector guide pin: guide for sliding of an ejector plate.

9. Ejector bolts: To tie up two ejector plate.

10. Sleeve ejector system.  It will push samples out of the mold.

II. How ejector system works?

1. After mold opening finished, rod of injection machine will push the ejector plate. Ejector plate will move forward. Ejector guide pin will guide those moving.

2. Ejector pins clamped between two ejector plate so it will move forward and push product out of the mold.

3. After we get the product, rod of injection machine will move back. Spring of return pin will push ejector plate move back. Spring and mold closing will guide ejector back to the position.

III. Ejector system can not return. How do we do?

Ejector system must return before mold closed. If they can not return that will crack and cavity of mold could be scratch, crack. And mass product can not continue.
Reason:
+ Have trash on the ejector pins, oil and maintaining is bad.
+ Worker assembly ejector pins not good.
+ Angular pins were cracked when injection.
+ Resin were stuck in mold.
+ Temperature is difference between a core plate, a cavity plate, pins.
How do we do to solve the problem.
+ Have trash on the ejector pins, oil and maintaining is bad. You should clean the mould and add the lubricating oil.
+ If injection processing and you don’t see pins or core crack, don’t want stop injection, you can use cleaner. But I think your mold will NG faster.