Slush Casting Alloys

Overview

Slush-cast alloy is a high-purity purpose-engineered product manufactured by Eastern Alloys. This alloy was developed to provide a high fluidity casting material capable of producing a good surface definition when cast in metal permanent molds or rubber molds. It contains approximately 5% aluminum and 95% zinc giving it a very short freezing range, and good fluidity.

In the slush casting process, metal is poured into a slush-casting mold, allowed time to solidify along the mold wall only, and then poured out. The resulting "hollow" casting is then ejected and cooled. Its primary use is for decorative castings not subjected to high stress conditions, such as lamp bases.

Because of the low melting temperatures and excellent fluidity, the alloy should be cast at temperatures not to exceed 825°F. Since the alloy is normally melted and held in cast iron kettles, high temperatures will cause excessive iron pickup, resulting in poor castability and poor finishing characteristics.

Since the alloy contains no Magnesium (to ensure high fluidity) extreme care must be taken to prevent contamination by Pb (lead), Sn (tin) or Cd (cadmium) which can cause subsequent inter-granular corrosion. Castings are normally plated soon after finishing to preclude any oxidation or corrosion problems.

Properties

Ultimate Tensile Strength 25,000 psi (chill cast)
Elongation 1%
Impact Strength 1 ft-lb
Melting Range 716-743°F
Density 0.24 lb/cu in
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