Description:
Warpage in injection molding is the result of unequal volumetric shrinkage of material throughout the geometry of the piece as it cools from a melt to a solid state. Before the part is ejected, the deformation of warpage has been developed inside the mold. The influence of in-mold constraint for warpage is different according to the time of in-mold period. In general the warpage will be smaller when the in-mold period is longer. The warpage with in-mold constraint effect is complicated phenomena. The contact behavior will be induced between rigid mold and plastic part. The part can't shrink and warp freely at in-mold stage due to the rigid mold. Besides, this contact behavior also induces the stress of part.