Die Cast Zinc Alloy Properties
Zinc’s high strength and hardness lends itself to many solutions and it’s the ideal alternative to machined, pressed, stamped, and fabricated components. Zinc alloys are the easiest for die casting. Ductility is high and impact strength is excellent, making these alloys suitable for a wide range of products. Zinc die casting provides thin walls and excellent surface smoothness making preparation for plating and painting relatively easy. See our Alloy property guide for additional information.
Zamak No. 3
The most widely used zinc alloy is commonly called No. 3. Its excellent all-around physical and mechanical properties, superb cast-ability, and long-term dimensional stability have made it the choice for about 85% of U.S. die-castings. In most design applications using a zinc alloy, No. 3 will do the job. In general, only after casting design improvements have been evaluated and found inadequate should another alloy be considered.
Zamak No. 5
The addition of about l% copper to the No. 3 alloy provides increased tensile strength (about 15%) and higher hardness at the expense of elongation and impact strength. No. 5 alloy is widely used in Europe, but accounts for less than 10% of U.S. consumption.
Zamak No. 7
The third most popular alloy is a high purity, low magnesium alloy called No. 7. This alloy has improved fluidity (because of the lower magnesium content) allowing it to be cast at lower temperatures for better as-cast surface finish and higher production rates. Most No. 7 alloy is used in decorative hardware applications. Since it possesses slightly more ductility than other zinc alloys, No. 7 is also used where castings require severe deformation in assembly operations.
Zamak No. 2
Actually, a predecessor of the universal No. 3 alloy, No. 2 offers the highest strength and hardness available in a conventional zinc alloy. It is about 25% stronger as cast than No. 3 and 10% stronger than No. 5 with higher hardness than both.
The principle disadvantages of this interesting alloy are its very low impact strength and elongation after aging (especially at higher temperatures) and a slight dimensional instability with aging.
Offers best plating and finishing characteristics with improved strength, hardness and creep properties compared to the other conventional zinc ZAMAK die casting alloys. Major application area is usually for die casting where improved properties over ZAMAK’s are required, particularly performance at elevated temperatures.
This is the most recent development in commercially available zinc die casting alloys. Research has shown EZACTM to be the most creep resistant of all the zinc die casting alloys with over an order of magnitude improvement over ZAMAK 5 and ZA-8. This is also a very strong alloy with a yield strength (57 ksi) and hardness (102-134 brinell) comparable to ZA-27.
Due to its low melting temperature, EZACTM can be cast in a hot chamber die casting machine and does not exhibit the same wear and tear as shown with ACuZinc®5.
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