The part shrinkage can be defined in terms of either the part length or the part volume. As shown here, L sub part is the length of the part after molding and L sub mold is the length of the mold. Linear shrinkage, S L is approximately one third of the volumetric shrinkage S V for isotropic parts.
True shrinkage is evaluated with the dimensions of the hot mold.
Material properties include PVT data, thermal properties, viscosity etc. Part geometry parameters include part thickness mold constraints like ribs and bosses. Manufacturing parameters include temperature, pressure, fill time etc. Part shrinkage is a system property that depends on the combination of all of the above parameters. Warpage causes the post mold shape of plastic parts to differ from the mold cavity shape.