Abstract
All the casting prepared for the present experiment could not be produced without any shrinkage and deformation. Although asbestos lining surely decreased the cast shrinkage, the casting could almost never become larger than the wax pattern. Under the circumstances the conventional crown model of the casting, of which the core height is three quarters of the outer side wall height, could have larger concave than the wax pattern by lining the ring with two folds of wet asbestos or more. Such a deformation favorable for the good fitness may possibly be caused by larger size of the core. Results of the pressure measurement on the pattern in the investment revealed that the anisotropic and heterogeneous setting expansion of the investment in the casting ring would be induced by the presence of the wax pattern itself. The investment is partitioned by the pattern into two parts, the core portion and the portion between the pattern and the ring wall. Each portion of the investment would seem to behave somewhat independently in setting. The well fitting of the crown casting may be attributed never to the full compensation for the cast shrinkage, but to the favorable deformation caused by the beneficial expansion of the core and the impediment of it to the free contraction of the cast alloy in solidification.
