Numerical analysis of thermal stress and shrinkage of wax patterns. III. Effects of physical properties and cooling conditions.

Thermal stresses in three brands of inlay waxes were numerically analyzed under different cooling conditions using the rheological and thermal properties of waxes. On the basis of this analysis , the shrinkage of the wax pattern was calculated. The larger the stress relaxation of the wax and the higher the ambient temperature, the smaller the thermal stress induced in the wax. The shrinkage of the wax pattern that was restrained by the die was extremely smaller than that of the male portion of the pattern . This indicates that the stress relaxation of the wax contributed greatly to the restriction of shrinkage of the wax pattern at the male portion of the die.