Abstract: The free energy of a metal which will fill the sinkhead of an ingot mold is calculated by assuming the dimensions of a liner sized to achieve the selected sinkhead volume and calculating the maximum temperature which the liner would achieve upon filling the sinkhead with a molten metal. The free energy is maximized until the mass of the liner is minimized at a calculated temperature less than the melting temperature of the liner. A liner is formed having dimensions corresponding to those of the calculated minimum mass liner. The liner is inserted into a support structure which will rest on the ingot mold.

Abstract: A reusable hot top includes a shell having an aperture therethrough providing an inner wall. The shell has an upper end portion and a lower end portion which seats on a mold. A liner comprised of an insulating material is positioned in the aperture and is movable relative to the upper and lower end portions. Insulation is sandwiched between the liner and the inner wall and prevents heat conductance between the liner and the shell. Pins extend from the inner wall and are engaged with and support lugs extending from the liner and thereby maintain the liner in the aperture when the shell is lifted from the mold and the pins are disengaged from the lugs when the shell is seated on the mold. A thermal seal is disposed around the bottom of the liner and contacts the mold. The seal prevents the liner from contacting the mold and thereby prevents heat conductance between the liner and the mold.