Zamak 3 (Zinc Alloy 3) -The Most Widely Used Zinc Die Casting Alloy

Zamak 3, also designated Alloy 3 or Zinc Alloy No. 3, is the benchmark zinc die casting alloy globally. It accounts for the majority of all zinc die casting production and is the default choice when no other zinc alloy is specified. Its combination of excellent casting performance, balanced mechanical properties, outstanding surface finish, and suitability for decorative electroplating has made it the industry standard for zinc die casting across hardware, automotive trim, electronics, and consumer products.

The name ZAMAK is an acronym from the German words for Zinc (Zink), Aluminum (Aluminium), Magnesium, and Copper (Kupfer) -the four principal elements in the alloy family.

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Chemical Composition

Element	Nominal %	Allowable Range
Aluminum (Al)	4.0	3.9-4.3
Magnesium (Mg)	0.04	0.03-0.06
Copper (Cu)	-	0.10 max
Iron (Fe)	-	0.075 max
Lead (Pb)	-	0.005 max
Cadmium (Cd)	-	0.004 max
Tin (Sn)	-	0.003 max
Nickel (Ni)	-	0.001 max
Zinc (Zn)	Balance	-

Per ASTM B86 and NADCA Product Standards

Note: The extremely tight limits on lead, cadmium, and tin are not cosmetic -even small amounts of these impurities cause inter-granular corrosion ("zinc pest") in Zamak alloys. KastMfg uses only certified Special High Grade (SHG) zinc ingot meeting 99.99% minimum purity.

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Mechanical Properties

Property	Value
Tensile strength	283 MPa (41,000 psi)
Yield strength	200 MPa (29,000 psi)
Elongation	10%
Hardness	82 HRB
Shear strength	214 MPa (31,000 psi)
Compressive yield strength	414 MPa (60,000 psi)
Impact strength (Charpy, unnotched)	58 J (43 ft·lbf)
Fatigue strength (5x10^8 cycles)	48 MPa (7,000 psi)

Note: Zamak 3's 10% elongation makes it significantly more ductile than Zamak 5 (7%) -it absorbs impact without cracking.

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Physical Properties

Property	Value
Density	6.60 g/cm³ (0.238 lb/in³)
Melting range	381-387°C (718-728°F)
Casting temperature	400-430°C
Thermal conductivity	113 W/m·K
Electrical conductivity	27% IACS
Coefficient of thermal expansion	27.4 μm/m·°C
Modulus of elasticity	86 GPa (12,500 ksi)
Poisson's ratio	0.27

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Why Zamak 3 is the Default Zinc Die Casting Alloy

Lowest cost of ownership at high volume. Zamak 3's casting temperature of 400-430°C is gentle on H13 die steel. Hot-chamber dies running Zamak 3 regularly exceed 500,000 shots before requiring major maintenance -a 3-x improvement over equivalent aluminum dies. This dramatically reduces tooling amortization per unit.

Outstanding castability. Zamak 3's low viscosity and freezing range of only 6°C (essentially isothermal solidification) allow reliable filling of walls as thin as 0.4 mm and fine surface detail that requires no post-processing.

Smoothest as-cast surface. Zamak 3 produces as-cast surfaces of Ra 0.8-1.6 μm -smoother than any aluminum die casting alloy. This smooth base is essential for decorative plating.

Best substrate for decorative electroplating. Zamak 3 is the global standard substrate for decorative chrome, nickel, gold, and copper plating. The smooth surface, consistent alloy chemistry, and established plating process compatibility make Zamak 3 the choice for visible consumer-facing and automotive trim components.

High ductility. At 10% elongation -the highest of the Zamak family -Zamak 3 absorbs impact without brittle fracture. This is important for components subject to drop loading, vibration, and assembly forces.

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Zamak 3 vs Zamak 5

Parameter	Zamak 3	Zamak 5
Copper content	0.10% max	0.75-1.25%
Tensile strength	283 MPa	331 MPa
Elongation	10%	7%
Hardness	82 HRB	91 HRB
Ductility	Higher	Lower
Creep resistance	Standard	Better
Plating suitability	Excellent	Excellent
Cost	Baseline	+3-%

Choose Zamak 3 when: ductility and impact resistance are more important than strength; decorative plating is required; standard hardware, locks, and consumer product applications.

Choose Zamak 5 when: the part is load-bearing; higher tensile strength is needed; creep resistance at slightly elevated temperatures is required.

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Surface Finishing for Zamak 3

Zamak 3 accepts the full range of decorative finishes:

Finish	Result	Common Applications
Decorative chrome plating	Mirror or satin chrome	Automotive door handles, bath fittings
Nickel plating	Warm silver appearance	Hardware, connectors, fashion
Gold plating	Warm gold appearance	Jewelry findings, luxury hardware
Copper plating	Reddish-copper appearance	Decorative hardware, electrical
Powder coating	Any color	Industrial, outdoor
Painting	Any color	Consumer products
Clear lacquer	As-cast metallic appearance	Visible castings without plating

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Applications

Automotive: Door handles, lock cylinders, ignition bezels, interior trim components, fuel cap covers, mirror housings. Zamak 3 is the industry standard for high-volume zinc automotive trim.

Hardware and Building Products: Padlocks, deadbolts, window locks, cabinet hardware, furniture fittings, bathroom accessories. The combination of dimensional precision, plating suitability, and die economics makes Zamak 3 dominant in this segment.

Electronics: Connector housings, terminal blocks, relay housings, motor frames, switch bodies. Zamak 3's electrical conductivity and dimensional precision are well suited.

Consumer Products: Belt buckles, zip fasteners, eyewear hinges, sporting goods fittings, toy components. High volume, fine detail, and decorative appearance all favor Zamak 3.

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Dimensional Capability for Zamak 3 Die Casting

Parameter	KastMfg Specification
Minimum wall thickness	0.4 mm
Dimensional tolerance	CT3-CT5 per ISO 8062
Surface finish (as-cast)	Ra 0.8-1.6 μm
Weight range	0.005 kg -3 kg
Die life	300,000-400,000+ shots
Cycle time	15-25 seconds

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Frequently Asked Questions

What causes "zinc pest" and how do you prevent it?

Zinc pest (inter-granular corrosion) occurs when Zamak alloys contain trace impurities -particularly lead (>0.005%), cadmium (>0.004%), or tin (>0.003%). KastMfg uses only certified SHG zinc with documented purity, and verifies alloy chemistry on every melt by OES spectrometer. Correctly formulated Zamak 3 does not experience zinc pest.

Can Zamak 3 parts be used outdoors?

Bare Zamak 3 has moderate corrosion resistance adequate for dry indoor environments. For outdoor use, chrome plating, powder coating, or lacquer is required. Chrome-plated Zamak 3 (with nickel undercoat) performs excellently in outdoor and humid environments.

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Zamak 3 die casting inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China