Zamak


ZAMAK is an eclectic family of alloys with a base metal of zinc and alloying elements of aluminum, magnesium, and copper.
Zamak alloys are part of the zinc aluminum alloy family; they are distinguished from the other ZA alloys because of their constant 4% aluminum composition.
The name zamak is an acronym of the German names for the metals of which the alloys are composed: Zink, Aluminum, Magnesium, and Kupfer. The New Jersey Zinc Company developed zamak alloys in 1929.
The most common zamak alloy is zamak 3. Besides that, zamak 2, zamak 5, and zamak 7 are also commercially used. These alloys are most commonly die-cast. Zamak alloys are frequently used in the spin-casting industry.
A large problem with early zinc-die-casting materials was zinc pest, owing to impurities in the alloys. Zamak avoided this by the use of 99.99% pure zinc metal, produced by New Jersey Zinc's use of a refluxer as part of the refining-process.
Zamak can be electroplated, wet-painted, and chromate-conversion-coated well.

Mazak

In the early 1930s, Morris Ashby in Britain had licensed the New Jersey zamak alloy. The 99.99%-purity refluxer zinc was not available in Britain and so they acquired the right to manufacture the alloy using a locally-available electrolytically-refined zinc of 99.95% purity. This was given the name Mazak, partly to distinguish it from zamak and partly from the initials of Morris Ashby. In 1933, National Smelting licensed the refluxer patent with the intent of using it to produce 99.99% zinc in their plant at Avonmouth.

Standards

Zinc alloy chemical composition standards are defined per country by the standard listed below:
CountryZinc ingotZinc casting
EuropeEN1774EN12844
USASTM B240ASTM B86
JapanJIS H2201JIS H5301
AustraliaAS 1881 - SAA H63AS 1881 - SAA H64
ChinaGB 8738-88-
CanadaCSA HZ3CSA HZ11
InternationalISO 301-

Zamak goes by many different names based on standard and/or country:
The short European designation code breaks down as follows :
  • Z is the material
  • P is the use
  • 04 is the percent aluminum
  • 3 is the percent copper

    Zamak 2

Zamak 2 has the same composition as zamak 3 with the addition of 3% copper in order to increase strength by 20%, which also increases the price. Zamak 2 has the greatest strength out of all the zamak alloys. Over time it retains its strength and hardness better than the other alloys; however, it becomes more brittle, shrinks, and is less elastic.
Zamak 2 is also known as Kirksite when gravity-cast for use as a die. It was originally designed for low volume sheet-metal-dies. It later gained popularity for making short-run injection-molding-dies. It is also less-commonly used for non-sparking tools and mandrels for metal-spinning.

KS

The KS alloy was developed for spin casting decorative parts. It has the same composition as zamak 2, except with more magnesium in order to produce finer grains and reduce the orange peel effect.

Zamak 3

Zamak 3 is the de facto standard for the zamak series of zinc alloys; all other zinc alloys are compared to this. Zamak 3 has the base composition for the zamak alloys. It has excellent castability and long term dimensional stability. More than 70% of all North American zinc die castings are made from zamak 3.

Zamak 4

Zamak 4 was developed for the Asian markets to reduce the effects of die-soldering while maintaining the ductility of zamak 3. This was achieved by using half the amount of copper from the zamak 5 composition.

Zamak 5

Zamak 5 has the same composition as zamak 3 with the addition of 1% copper in order to increase strength, hardness and corrosive resistance, but reduces ductility. It also has less dimensional accuracy. Zamak 5 is more commonly used in Europe.

Zamak 7

Zamak 7 has less magnesium than zamak 3 to increase fluidity and ductility, which is especially useful when casting thin wall components. In order to reduce inter-granular corrosion a small amount of nickel is added and impurities are more strictly controlled.

Uses

Common uses for zamak alloys include appliances, bathroom fixtures, die cast toys and automotive industry. Zamak alloys are also used in the manufacture of some firearms such as those from Hi-Point Firearms. In World War 2, zamak alloy buttplates were one of three variations common on Canadian and American-made.303 Lee Enfield rifles, particularly during mid-war production.