Calculating Plastic Mold Shrinkage

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Calculating Plastic Mold Shrinkage

What is Plastic Mold Shrinkage and How is it Calculated?

Plastic injection molding shrinkage is the contraction of a plastic molded part as it cools after injection. Most of the part shrinkage occurs in the mold while cooling, but a small amount of shrinkage occurs after ejection, as the part continues to cool.

After that, the part may continue to shrink very slightly for several hours or even days until the temperature and moisture content stabilize. Because of this, dimensional inspection should wait at least a day.

To compensate and plan for the shrinkage, the mold tooling engineer applies a calculation to expand the dimensions slightly. So how do you know how much? Visit this page of the Learning Center on our website for information on plastic injection molding shrinkage.

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