How to control shrinkage during injection molding?

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Material temperature
Controlling the temperature of the plastic resin when it is heated is important to control shrinkage. The hotter the material is before it is poured, the more the molecules expand. When it cools, these molecules contract back. The lower the temperature of the plastic when it is poured, the less shrinkage there will be during the cooling process.

Form temperature
Controlling the temperature of the mold can control shrinkage. Using a cold mold allows the outer edges of the part to dry before it can fill and compress the entire space properly. Using a hot iran number data mold will create less shrinkage than a cold mold. This allows the molecules of the plastic material to continue to move freely, filling the mold and achieving the correct pressure before cooling begins.

Pressure regulation
The amount of pressure used to inject the plastic material has a direct impact on shrinkage factors. This is the pressure needed to compact the material in place. The tighter the material is packed, the less room there is for movement as it cools. The higher the injection pressure, the less the plastic will shrink.

As long as pressure is applied until the plastic has hardened, shrinkage will be limited. If pressure is released before the plastic has completely cooled, shrinkage will worsen. Holding the plastic in place while it cools to reverse its normal shrinkage pattern controls shrinkage, but the process takes longer and is more expensive. Forced air blowing on plastic parts also helps stabilize them.