What Causes Shrinkage in Plastic Products? Key Factors Affecting Plastic Shrinkage Rate 2026-05-20
If you work in injection molding, product design, or plastic manufacturing, you must have encountered these common problems: inconsistent product dimensions, surface sink marks, uneven warping, or unstable mass production sizes. In most cases, the root cause is plastic shrinkage.
Plastic shrinkage is an unavoidable physical change during the injection molding process. When molten plastic fills the mold cavity and cools down from a high-temperature fluid state to a solid state, its molecular structure tightens and the volume shrinks. However, shrinkage is not fixed—it fluctuates greatly according to materials, mold designs, and production processes.
Today, we will break down four core factors affecting plastic shrinkage rate, helping you quickly troubleshoot defective products and optimize molding quality.
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