Shrinkage Allowance

As the casting cools, the metal shrinks. For common cast metals, a 1% shrinkage allowance is designed in all linear dimensions (namely, the design is scaled p by approx 1%). Since the solidification front, i.e. the surface

at the boundary of the solidified and the liquid metals, travels from the surface of the mold to the interior regions of the part, the design must ensure that shrinkage does not cause cavities.