Overview
Eastern Alloys manufactures mold-base alloys, also known as Kirksite alloys.
Kirksite is a moderate strength zinc-base alloy that was developed primarily as
a forming tool alloy. Dies cast from Kirksite provide low-cost tooling because
the alloy can be accurately cast, requiring a minimum of finishing. In
addition, Kirksite has been used as a general purpose casting alloy for
non-stressed components.
Typical uses for Kirksite alloys are:
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Press dies and punches for sheet metal forming.
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Molds for ceramics and rubber.
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Injection molding and compression molding dies.
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Tube bending dies.
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Mandrels for metal spinning.
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Low stressed non-sparking tools and repair parts.
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Properties
| Ultimate Tensile Strength |
35,000 psi
|
| Elongation in 2" |
2.0% |
| Impact Strength |
6 ft-lbs |
| Melting Range |
717-745°F |
| Density |
0.25 lb/cu in |
| Brinell Hardness |
100 |
| Solidification Shrinkage |
0.14"/ft |
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Comments
Because of the alloy's excellent fluidity and low melting temperature, casting
temperatures are low, 800-850°F. Higher casting temperatures should be avoided
due to possible iron contamination from the cast iron kettles normally used to
melt the alloy. Iron pickup can cause poor casting surface quality and
brittleness. Melting in a silicon carbide crucible is preferred as a safeguard
against iron pickup. The alloy is normally cast in permanent, plaster or sand
molds.
Kirksite is readily machined and polished. Castings can be successfully plated
following procedures used for zinc die-castings. Kirksite can also be cast in
rubber tooling as a replacement for slush casting alloy (ZA-5) when higher
strengths are required, with a sacrifice in fluidity.
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