Factors Affecting Postmold Shrinkage and Warpage

Most part shrinkage takes place within a very short time after the part is molded, typically within 16–48 h after demolding. The reduction in volume during this initial period is a result of solidification and thermal contraction as the molded part cools to room temperature. This rapid size change is influenced by the variables discussed in Chapters 2–6 Chapter 2 Chapter 3 Chapter 4 Chapter 5 Chapter 6 , namely material properties, part geometry, the runner and gate systems, melt temperature, mold temperature, injection pressure, holding pressure, and so on.