Zamak 2 Zinc Die Casting | Creep-Resistant Alloy

Zamak 2 (ZnAl4Cu3 per EN 1774, AC43A per older ASTM designation) carries 3% copper - triple the copper of Zamak 5 and the highest of the Zamak family. That copper makes Zamak 2 the strongest and most creep-resistant Zamak grade, at the cost of some ductility and long-term dimensional change that engineers must design around.

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Zamak 2 Chemical Composition

Element	Nominal %	Range
Aluminum (Al)	4.0	3.9 to 4.3
Copper (Cu)	3.0	2.6 to 3.3
Magnesium (Mg)	0.035	0.025 to 0.05
Iron (Fe)	-	0.075 max
Lead (Pb)	-	0.004 max
Cadmium (Cd)	-	0.003 max
Zinc (Zn)	Balance	-

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Mechanical Properties vs Zamak 3 and Zamak 5

Property	Zamak 2	Zamak 5	Zamak 3
Tensile strength	359 MPa (as-cast)	331 MPa	283 MPa
Yield strength	283 MPa	228 MPa	200 MPa
Elongation	6 to 7%	7%	10%
Hardness	100 HB	91 HB	82 HB
Creep resistance	Best of Zamak family	Good	Moderate
Long-term aging	Most pronounced of the family	Moderate	Least

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The Two Things to Know Before Specifying Zamak 2

1. Creep resistance. Under sustained load at elevated temperature, Zamak 2 deforms least of all Zamak grades. Threaded inserts, spring-loaded mechanisms, and clamped joints that must hold preload for years are the classic Zamak 2 use case.

2. Aging. The high copper content makes Zamak 2 age more noticeably than Zamak 3 or 5 - gradual dimensional change and some loss of ductility over years of service, accelerated by warmth. For press-fit bores and precision datums held over long periods, either design in margin or choose Zamak 5, which ages less.

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Applications

• Threaded insert housings and fasteners under sustained clamping load
• Gears, ratchets, and pinions in mechanisms
• Lock and hardware components requiring hardness and wear resistance
• Automotive under-hood hardware within the 100°C service limit
• Bearing retainers in moderate-speed service

For plated decorative parts, Zamak 3 remains the better choice - Zamak 2's hardness makes buffing and polishing slightly more labor-intensive, and its lower ductility is a liability for crimped or staked features.

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Zamak 2 vs Zamak 5 - Quick Selection

Choose Zamak 2	Choose Zamak 5
Sustained load / creep-critical joints	General structural hardware
Maximum hardness and wear resistance	Better ductility needed
Cost-insensitive performance parts	Cost-optimized volume parts
Dimensions tolerate long-term aging	Tight long-term tolerances

For the full family comparison, see Zamak 3 vs Zamak 5 and the zinc die casting alloys guide.

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Casting Zamak 2 at KastMfg

Zamak 2 runs in standard hot-chamber machines with shot temperatures around 415 to 430°C (melting range 379 to 390°C) - within normal Zamak process windows. KastMfg casts Zamak 2 for lock hardware, gear, and insert programs with SPC monitoring on critical dimensions, and we flag aging-sensitive tolerances at DFM review so press-fits and datums are designed correctly from the start.

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Frequently Asked Questions

Is Zamak 2 the same as Kirksite?

Not exactly. Kirksite is a closely related zinc-aluminum alloy family (essentially the Zamak 2 / ZnAl4Cu3 chemistry class) used for sheet-metal forming dies, prototype tooling, and short-run tooling rather than production die cast parts.

Can Zamak 2 be chrome plated?

Yes. Plating quality is comparable to Zamak 5 with standard copper-nickel-chrome stacks. Surface preparation matters more than the alloy difference.

When should I avoid Zamak 2?

Avoid it for parts with tight press-fit tolerances held over many years (long-term aging), parts requiring staking or crimping (low ductility), and any application where Zamak 5 already meets the load case - Zamak 2 costs more and casts slightly slower.

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Related Zinc Resources

• zinc die casting - hot-chamber production capability
• Zamak 3 - the default general-purpose alloy
• Zamak 5 - the balanced strength upgrade
• zinc die casting alloys - full Zamak and ZA selection guide

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Zamak 2 inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China