Parkins and Cowan’s model is considered appropriate in explain the measurement of the condition in which the castings are under a relatively low restraint force from the sand mold. However, under a relatively high restraint force condition (for example, the large and small flange castings in the furan sand mold), the experimental results demonstrated that the free-to-experimental contraction difference curve exhibited a different behavior from that of the low restraint force condition during cooling.
Therefore, it is necessary to examine the other model to explain the free-to-experimental contraction difference curve during cooling for the relatively high restraint force condition.