What causes shrinkage in injection Moulding?

Cnmoulding12 Aug, 2025Technology

Thermoplastics are characterized by expansion after heating and contraction after cooling. Of course, the volume will shrink after pressurization. In the injection molding process, the molten plastic is first injected into the mold cavity. After the filling is completed, the melt is cooled and solidified. When the plastic part is taken out of the mold, shrinkage occurs. This shrinkage is called forming shrinkage. During the period of time when the plastic part is taken out from the mold to stable, there will still be slight changes in size. One change is to continue to shrink. This shrinkage is called post-shrinkage.