The Injection Molding Process


Whether your an existing customer or just a curious George, you might be wondering “what exactly does the process of injection molding entail?”

We have broken it down for you step by step so that you can understand exactly what happens during this process. An injection molding machine constists of three basic parts; the mold plus the clamping and injection units.

The clamping unit holds the mold under pressure during the injection and cooling. Basically, it holds the two halves of the injection mold together.

During the injection phase, plastic material, usually pellets, are loaded into a hopper on top of the injection unit which are heated until they are melted.

There is a motorized screw that then pushes the pellets to the end of the cylinder. Once enough material has accumulated in front of the screw, the injection process begins.

The molten plastic is inserted into the mold through a sprue, while the pressure and speed are controled by the screw.  Note: some injection molding machines use a ram instead of a screw.

After the melted plastic has been injected into the mold and the pressure is applied to make sure all of the mold cavities are filled the dwelling period is sort of a waiting period.

We allow the plastic to cool so it can become a solid form within the mold.

Mold Opening
The clamping unit is opened, causing two halves of the mold to separate

An ejecting rod and plate eject the finished piece from the mold. The un-used sprues and runners can be recycled for use again in future molds.

You can also check out this video to get a better idea:



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