Abstract: Castings are produced in a bed of production sand susceptible to both fluidizing and vacuumizing. The use of a vacuum at the time the molten metal is poured permits the use of thin shell molds made around styrene patterns, the vacuum maintaining mold shape and drawing out gases produced by the vaporizing pattern and otherwise. The produced casting is rapidly cooled in the bed while it is fluidized, the fluidized sand achieving good heat conduction. The casting is then heat stabilized while the bed is defluidized, the bed then becoming a good insulator. An austempering curve can be followed, thereby having the effect of heat treating in the same bed as used for casting production.