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Analysis of experiments involving a cylindrical column of lead in the process of freezing downward or alternatively, of melting upward from the base of the container, showed that heat transfer rates associated with Be´nard convection are less under transient conditions than at steady-state. Analysis of experiments involving the freezing of lead-tin alloys (0.2 – 1.6 wt. percent Sn) showed that the same heat transfer correlation for Be´nard convection could be applied, provided the upper bounding “interface” was located on the solidus isotherm for planar and cellular alloy growth, and on the liquidus, for cellular-dendritic alloy growth.

Aluminium A356 (AlSi7Mg03) is the most common foundry alloy poured in sand and permanent molds or lost-wax shells. Because of its magnesium content, this alloy responds to a precipitation hardening treatment. The strength and ductility combination of the alloy can be varied at will by changing the temper treatment that follows the solutionizing and quenching of the part. By feeding the mold from the bottom, the low-pressure process provides a tranquil filling of the cavity. A perfect control of the liquid metal stream is provided by programming the pressure rise applied on the melt surface. It compares favorably to the more common gravity casting where a turbulent filling is governed by the geometry of the gating system.

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