Abstract: The method and apparatus of the present invention substantially reduce the incidence of cracking, flaking, bulging and other mold defects which originate during the drying step of the investment mold formation process. Drying is conducted under conditions which enhance uniformity of drying and which preclude harmful increases in pattern temperature resulting from changes in the moisture removal kinetics of the slurry layer. In particular, during the drying process, drying air of different quality is provided during the different stages of moisture removal from the slurry layer.

Abstract: The method and apparatus of the present invention substantially reduce the incidence of cracking, flaking, bulging and other mold defects which originate during the drying step of the investment mold formation process. Drying is conducted under conditions which enhance uniformity of drying and which preclude harmful increases in pattern temperature resulting from changes in the moisture removal kinetics of the slurry layer. In particular, during the drying process, drying air of different quality is provided during the different stages of moisture removal from the slurry layer.

Abstract: The present invention provides an improved method for making ceramic slurries useful in forming casting molds. The method involves placing the slurry ingredients in a mixing container, removing sufficient air from the container to prevent subsequent air entrapment, mixing the slurry ingredients by epicyclic agitation to effect rapid particle wetting and homogenization and removing the slurry from the container after agitation is terminated, the ceramic slurry being ready for immediate use. Total slurry preparation time is generally one hour or less, as compared to the 24 to 36 or more hours required for prior art slurry preparation techniques.