Abstract
Usually, prosthesis are manufactured by the casting technique.To make precise castings, high technical skill and attention are required.Heating of mold is not only required for dewaxing but for many important roles, such as mold strengthening, ensuring air-permeability of mold and preheating for precise casting.To fill these roles, temperature control during the heating process is essential.Although it is known experimentally that the temperature varies with the position in the furnce and the mold temperature varies depending on the arrangement of the molds, no precise study about this problem has been reported.In the present study, the temperature distribution in the furnace without mold and actual mold temperatures placed in the furnce were measured and recorded using a conventional furnace which is usually used in the dental clinic.Experimental data were examined from the view points of temperature changes due to heating and cooling, mold size and arrangement in the furnace.With no molds, less temperature difference was measured between top and bottom of the furnace and also between right side and left side.However, it is observed that much temperature difference exists between door side and deep of the furnace.When the molds were put in the furnace, there was less temperature differences among the molds which were placed crowded together at the center of the furnace than when the molds were placed scatteringly from door side to deep of the furnace.Temperature differences among molds became larger at elevated temperatures due to influence of heat radiation.It is concluded that detailed studies on the relationship between mold temperature changes during heating and results of castings are necessary to build a better casting system for dental materials.
