Zamak alloys: what they are, which grade to use and where they fit

Zamak is a family of zinc casting alloys with about 4% aluminum plus small additions of magnesium and, in some grades, copper. Zamak 3 is the default grade, Zamak 5 adds roughly 1% copper for strength, Zamak 2 adds about 3% for more, and Zamak 7 is a high-purity version of Zamak 3 for thin, cosmetic parts. All of them melt at around 380–390 °C, low enough to run in a hot chamber machine: shorter cycles, longer die life and fine detail that aluminum struggles to hold. The real choice is which grade, for which part, and what it demands of the cell.

What is Zamak?

Zamak is zinc alloyed with aluminum, magnesium and copper. The name comes from the German initials of those four elements: Zink, Aluminium, Magnesium and Kupfer. In North America the die castings are covered by ASTM B86 (ingot by ASTM B240), which is where the designations you will see on a certificate come from — AG40A, AC41A, AG40B, AC43A — alongside the commercial names Zamak 3, 5, 7 and 2. In Europe the same family is specified under EN 12844 for castings and EN 1774 for ingot, as ZP3 (ZnAl4), ZP5 (ZnAl4Cu1) and ZP2 (ZnAl4Cu3), according to the International Zinc Association’s alloy specification page.

• Aluminum (3.7–4.3% in all four grades under ASTM B86) is what makes zinc workable in a hot chamber machine: the International Zinc Association notes that below about 450 °C it “drastically reduces the rate of attack of ferrous materials by the molten alloy”. It also raises strength and hardness.
• Magnesium, at 0.02–0.06% in Zamak 3 and 5, suppresses intergranular corrosion. The IZA warns that above about 0.1% castings tend to crack under shrinkage stresses while still in the die.
• Copper raises strength and hardness, and costs ductility: elongation drops from 10% in Zamak 3 to 7% in Zamak 5 and Zamak 2 (Eastern Alloys datasheets, die-cast values).
• The zinc base itself has to be high purity: Zamak 3 die castings allow 0.005% lead, 0.004% cadmium and 0.002% tin at most (ASTM B86), because small amounts of these elements make the alloy vulnerable to intercrystalline corrosion, especially in warm, humid service (IZA). Those impurity limits, not the headline percentages, are what actually protects the part.

Zamak is not pure zinc: without the aluminum, molten zinc attacks the steel of the machine and the die.

Zamak 3, Zamak 5 or Zamak 7: which grade to use

Sources: Eastern Alloys datasheets for Zamak 2, 3, 5 and 7 (ASTM B86 die-cast limits, typical properties), consulted 2 October 2026; EN 12844 designations from the International Zinc Association. Typical values, not minimums.

Zamak 3 is the correct answer until something forces you off it: it casts predictably, finishes well and, per Eastern Alloys, accounts for nearly 70% of zinc die castings in North America. Move to Zamak 5 when the part must carry load or resist wear, trading away some ductility. Move to Zamak 7 when the part is thin, cosmetic or both, knowing that its lead, cadmium and tin limits (0.003%, 0.002% and 0.001%) demand cleaner metal in the pot. Zamak 2 is the specialist, for when hardness or creep decides the part.

Zamak 3 vs Zamak 5 in practice

The two differ by one element — copper — and it shows in four places:

• Strength and hardness. Zamak 5 wins (328 MPa and 91 HB against 283 MPa and 82), and that is the only reason that should carry the decision.
• Ductility. Zamak 3 keeps more (10% against 7%), which matters for staked, riveted or crimped features.
• Long-term dimensional stability. Copper works against it (Eastern Alloys quotes 0.0014 in/in of growth after 20 years for Zamak 2). For tight fits that must last years, Zamak 3 is the safer default.
• Availability. Zamak 3 dominates in North America, Zamak 5 in Europe.

Switching grades does not fix a defect that belongs to the die: filling problems and porosity rarely go away with a new alloy certificate.

What is the melting point of Zamak?

Zamak 3 melts over a range of 381–387 °C (718–728 °F); Zamak 5 over 380–386 °C and Zamak 2 over 379–390 °C, per the Eastern Alloys datasheets. A380, the most common aluminum die casting alloy, melts at 1000–1100 °F (about 540–595 °C) on the same supplier’s datasheet: roughly 150–210 °C higher before any superheat is added. Three consequences follow:

1. Hot chamber casting is possible. The injection system sits in the melt and cycles get shorter. What that means for the machine itself is laid out in die casting machine types and tonnage.
2. Die life is long. The International Zinc Association gives a typical die life of around 1 million shots for zinc, against typically around 200,000 for aluminum. The tooling side of that arithmetic is in die cast tooling.
3. Fine detail holds: thin ribs, small threads and crisp edges that would be a fight in aluminum.

Worked example: the same part in Zamak 3 and in A380

Take a typical case — a latch housing with a volume of 25 cm³, an annual volume of 200,000 parts and a three-year program, so 600,000 shots on a single-cavity die. The figures below are the published ones; swap in your own volume and quantity.

The zinc part weighs about 2.4 times as much; the aluminum program needs three dies where zinc needs one. Which side wins is metal price per kilo against die cost, to be run with your own quotes before the material is frozen on the drawing. If the part is mass-sensitive, the weight row has already decided.

Zamak material properties: how to read the datasheet

The grade table gives typical die-cast figures; for design, take them from the supplier’s certificate, stating grade, casting condition and test specimen. Beyond strength, two properties usually drive the choice:

• It is not a high-temperature material. Zinc alloys creep under sustained load. The IZA notes that, historically, an upper service temperature of 100 °C was applied to Zamak 3 (ZP3) and Zamak 5 (ZP5) castings in stressed applications and 150 °C in unstressed ones, raised to 130 °C stressed for Zamak 2 (ZP2). A bracket carrying load next to a motor at 110 °C is outside that rule of thumb for Zamak 3 and 5.
• Machinability and platability are excellent, so most zinc parts are plated, painted or chromated.

Does Zamak corrode?

Zinc corrodes protectively rather than catastrophically. The International Zinc Association states that where zinc or galvanized steel is satisfactory, zinc die castings usually behave well too, except in severe marine environments. Where condensation sits on the surface for long periods, they form the same “white rust” as galvanized steel: cosmetic on a bare part, a reject on a finished one. The finish is the real corrosion specification.

The failure mode to know is intergranular corrosion: driven by lead, cadmium and tin in the base metal, it swells and cracks the part months or years into service. Magnesium suppresses it, high-purity zinc prevents it, and sloppy recirculation brings it back. The melt charge is an engineering decision.

What zinc gives you, and what it charges for

Zinc buys geometry and tooling life, and charges weight (165 g against 68 g in the example) and surface. Plating is unforgiving: cold shuts, flow marks and porosity that would not matter in an aluminum housing become rejects after the finishing line. The finishing requirement defines the process window for many zinc parts, not the mechanical drawing.

What Zamak die casting demands from the cell

Hot chamber machines are not small cold chamber machines. The gooseneck and the nozzle are consumables, and their wear shows up in the part before it shows up in maintenance. Three things deserve routine attention:

• Thermal control of the die, because zinc cycles fast and an unbalanced die drifts quickly.
• Gate and overflow design, which for thin cosmetic parts is where the surface finish is actually decided.
• Melt cleanliness and recirculation policy, since the impurity limits that define grades like Zamak 7 are only meaningful if the charge respects them.

The process logic — filling phases, intensification, ejection — is the same as in aluminum, as laid out in die casting explained: how the process works.

Zamak in Mexico: where the metal and the drawings come from

The USGS Mineral Commodity Summaries 2026 estimate Mexican zinc mine production at 780,000 tonnes in 2025, fifth among the countries listed, and put Mexico at 15% of US refined zinc imports in 2021–24. For a die caster in Saltillo, Monterrey, Querétaro or the Bajío, the practical point is which standard the drawing calls: a US customer’s usually ASTM B86 (AG40A, AC41A), a European OEM’s EN 12844 (ZP3, ZP5). They are near equivalents, not identical, so check the certificate against the standard on the drawing, not the commercial name.

Inytialgo works with plants running aluminum, zamak and magnesium across Mexico, and our 20-hour course on gating design for aluminum, zamak and magnesium covers the zinc side of the gating decision.

Where Zamak parts actually show up

Zamak casting concentrates in parts where the value is in the geometry rather than in the mass: locks, latches and door hardware; connector bodies and electronics housings; gears, levers and small mechanisms; decorative trim. All share a demanding shape, a tight tolerance and enough volume to pay for long-lived tooling. When a part is large, structural or weight sensitive, zinc drops out early and the conversation moves to aluminum and cold chamber — a different die concept and a different cost structure per shot.

Where to start if you are evaluating zinc

If the material is still open, run the worked example with your own numbers first: part volume, annual quantity and program life give you metal per part and dies per alloy in ten minutes. If geometry, finish and volume still point to zinc, pick the grade from the table, starting at Zamak 3.

Our consulting starts from the real part and its defect history, training covers this chain of decisions for the team that will make it every week, and the simulation software is what lets that team see the filling before the steel is machined.