Second, the interaction between inertial forces and the vector of the gravitational acceleration induces the so-called pumping effect, responsible for thorough mixing, the growth of fine equiaxed grains, and superior mechanical properties of the cast.Īs with many other industrial processes, horizontal centrifugal casting has been studied with increased attention, with the help of various numerical techniques, in order to gain a better understanding of the process and underlying physical phenomena. First, it is the fictitious centrifugal force making the production of axisymmetric hollow castings even possible by pushing the molten metal against the inner wall of the cylindrical mold. In this process, the effect of centrifuging is twofold. Horizontal centrifugal casting is an important industrial process used especially for the production of high-quality seamless tubes and outer shells of work rolls. Later, when the air gap is formed, h drops exponentially to values at least one order of magnitude smaller (~ 100 Wm −2 K −1). Initial values of h are simply equivalent to the ratio of the coating thermal conductivity and its thickness (~ 1000 Wm −2 K −1).
Results demonstrated that the scenario at the interface is unique for each set of parameters, hindering the possibility of employing empirical formulas without a preceding experiment being performed. Several numerical tests were performed for different coating thicknesses d C, rotation rates Ω, and temperatures of solidus T sol. The numerical approach proposed here is rather novel and tries to offer an alternative to the empirical formulas usually used in numerical simulations for a description of a time-dependent heat transfer coefficient h. Here, the heat transfer coefficient at the cast-mold interface h has been determined from calculations of the air gap thickness d a based on a plane stress model taking into account thermoelastic stresses, centrifugal forces, plastic deformations, and a temperature-dependent Young’s modulus. In addition to the refractory coating, an air gap begins to form due to the shrinkage of the casting and the mold expansion, under the continuous influence of strong centrifugal forces.
During centrifugal casting, the thermal resistance at the cast-mold interface represents a main blockage mechanism for heat transfer.
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