Metal/Mold and Mold Environment Interfacial Heat Transfer
Coefficients in
Active and Passive Cooling of Investment Castings
Keith A. Woodbury, Jonathan W. Woolley, Thomas S. Piwonka, and Michal Pohanka
American Foundry Society Transactions, Volume 111, 2003
ABSTRACT
Cooling of an investment casting is governed by the nature
of the heat flow path through the mold wall, including the interfacial heat
transfer coefficient between the metal and the mold and the interfacial heat
transfer coefficient between the exterior of the mold and the environment. Many properties of the finished casting depend
strongly on the cooling rate during solidification. One means of enhancing the cooling of a
casting is by active cooling of the mold by immersion in a fluidized bed.
This paper presents the results of an experimental
investigation to determine the heat transfer coefficients on the inside and
outside of an aluminum casting investment mold.
A simple cylinder (25 mm diameter and 300 mm length) was used as the
basis for the experiments. Each mold was
specially instrumented with four thermocouples, and additionally two
temperature readings were taken within each casting during each
experiment. Aluminum alloys A356 and
A206 were both tested and several replications for each condition were
made. Both passive cooling (air cooling)
and active cooling (fluidized bed) were investigated.
