Advancements in Vacuum Process Molding and Casting
Type of DegreeThesis
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Vacuum assisted molding, or ‘V’ Process molding, possesses many benefits over other sand casting processes. However, the process lacks the high cooling rates and speed of solidification that other sand casting processes have. The research in this thesis includes the comparison of the solidification times between three different mold medias, theoretical estimation of the effective thermal conductivity of each mold media, predictions of solidification times and secondary dendrite arm spacings, as well as the casting of a cored valve plate using ‘V’ Process Molding. Step patterns, with step volumes of 41 cm3, 82 cm3, 123 cm3, and 164 cm3, were cast using aluminum A356.2 in three different mold medias: silica sand, zircon sand, and copper particulate. The solidification times of each step were theoretically predicted using a number of models available in the literature and compared with experimental data. Secondary dendrite arm spacings were also estimated from several theoretical models and compared with measured secondary dendrite arms from the experimental castings. Statistical analyses were performed to discern any significant difference between the solidification times of the aluminum alloy in each of the molds. A cored valve plate was also successfully cast in A356.2 aluminum alloy and AZ91E magnesium alloy using the V-Process. For the casting of magnesium, a standard operating procedure was prepared to safely avoid all potential hazards of the magnesium metal.