What is Zamak zinc alloy?
Zamak is a family of zinc-based die-casting alloys modified with small amounts of aluminum (≈3.5–4.3%), magnesium (≈0.02–0.06%), and copper (0–3%).
These additions raise strength, improve fluidity and creep resistance, and make the alloy stable enough for precision die casting and decorative plating.
Pure zinc is too soft and creeps under load; Zamak fixes that while keeping zinc’s great fluidity and low melt temperature.
What are the main Zamak grades 2, 3, 4, 5, and 7?
Across markets you’ll see five mainstream grades: Zamak 2, 3, 4, 5, and 7.
Zamak 2 has the most copper; it’s selected for long-term creep resistance and wear—think cams or small gear forms that stay under load for years.
Zamak 3 is the global default thanks to its balance of strength, ductility, castability, and plating response.
Zamak 4 sits between 3 and 5; a modest copper addition raises strength a little while keeping friendlier ductility.
Zamak 5 pushes copper further to deliver higher strength and hardness for small brackets and levers that carry load.
Zamak 7 lowers magnesium to improve ductility and fluidity, which helps on thin-wall, intricate parts and any design that needs a little post-forming.
Quick Grade Snapshot
| Grade | Core idea | Typical use cases (examples) |
|---|---|---|
| Zamak 3 | Global default: balanced strength, ductility, castability, plating | General hardware, housings, connectors, trim |
| Zamak 4 | Mid-Cu grade (between Zamak 3 and 5): a bit more strength than 3 while keeping reasonable ductility; regional availability | Structural trim, small brackets, parts needing slightly higher strength than 3 |
| Zamak 5 | Higher-Cu for higher strength/hardness (lower ductility than 3/4) | Levers, lock bodies, brackets needing extra strength |
| Zamak 7 | Very low Mg for extra ductility and excellent fluidity | Thin walls, intricate detail, peening/forming after cast |
| Zamak 2 | Highest Cu; best creep/wear | Gears, cams, long-term load parts |
Zamak composition and mechanical properties
All Zamak grades contain roughly 3.5–4.3% aluminum and a trace of magnesium to stabilize the alloy.
Copper is the main slider: the more you add, the higher the strength and hardness—up to the Zamak 2 range—while ductility gradually drops.
In pressure die casting, you’ll typically see ultimate tensile strengths in the 250–360 MPa window, yields around 190–300 MPa, and elongation that ranges from ~2% (Zamak 2) to ~10–12% (Zamak 7).
Density clusters near 6.6–6.8 g/cm³, much heavier than aluminum but perfect for parts where a solid hand-feel is a feature, not a bug.
Quick Table
| Grade | Al (wt%) | Mg (wt%) | Cu (wt%) | Zn | Density (g/cm³) |
|---|---|---|---|---|---|
| Zamak 3 | 3.5–4.3 | 0.02–0.06 | ≤0.05 | Balance | ~6.6–6.7 |
| Zamak 4 | 3.5–4.3 | 0.02–0.06 | ~0.3–0.7 | Balance | ~6.6–6.8 |
| Zamak 5 | 3.5–4.3 | 0.02–0.06 | 0.75–1.2 | Balance | ~6.7–6.8 |
| Zamak 7 | 3.5–4.3 | ≤0.01 | ≤0.05 | Balance | ~6.6–6.7 |
| Zamak 2 | 3.5–4.3 | 0.02–0.06 | 2.5–3.0 | Balance | ~6.7–6.8 |
Zamak melting point and casting behavior
Zamak’s melting range is about 380–390 °C (716–734 °F)—far below aluminum. That lower temperature reduces thermal shock to tooling and allows very fast cycles.
The alloy’s fluidity supports thin, uniform walls and crisp edges, so brand marks and small features come out clean without aggressive machining.
Because Zamak solidifies quickly, gating and venting are still crucial; a good die will carry the melt to the last-to-fill areas, pull gases out through vents and overflows, and leave cosmetic faces free of witness marks.
Zamak advantages and limitations
The headline advantages are precision, surface quality, and finish options.
Zamak casts to tight tolerances and polishes to a level that takes decorative chrome or satin nickel beautifully. Tool life is long and energy input per shot is modest, so total cost at scale is competitive. Limitations mostly relate to weight and temperature.
Zamak is heavier than aluminum and not the best choice for sustained high-temperature service. If a design lives hot or where weight is king, an aluminum die-casting grade will likely be the better structural answer.
Zamak applications in die casting
You’ll meet Zamak in places where the eye and the hand both judge quality: furniture hardware with a deep luster, lock bodies that feel substantial, appliance knobs and controls that need tight geometry, cosmetic housings that blend seams, and interior automotive trim where plating and paint must be flawless.
The alloy is equally comfortable in small mechanisms—clips, cams, sliders—whose function benefits from Zamak’s dimensional stability and wear behavior.
Zamak vs aluminum die casting comparison
Aluminum wins on strength-to-weight and warm-service capability; Zamak wins on detail, plating, and cycle economics.
Aluminum’s density is ~2.7 g/cm³ versus Zamak’s ~6.7 g/cm³, so weight-critical parts typically go aluminum.
But aluminum’s higher melt temperature shortens die life and makes mirror-chrome finishing unrealistic; anodizing or paint is the standard route.
If you’re buying parts that must be perfectly cosmetic, with very fine lettering, sharp radii, and repeatable fit, Zamak is usually the faster, safer path to a Class-A result.
| Factor | Zamak | Aluminum (e.g., A380/ADC12) |
|---|---|---|
| Density | ~6.6–6.8 g/cm³ (heavier) | ~2.7 g/cm³ (lighter) |
| Melt range | ~380–390 °C | ~570–620 °C |
| Die life | Longer (lower thermal shock) | Shorter (higher thermal load) |
| Cycle time | Very fast (short shot + solidification) | Fast, but slower than Zamak |
| Detail/thin walls | Excellent | Good |
| Plating | Outstanding (Cu/Ni/Cr) | Limited; anodize/paint preferred |
| Strength-to-weight | Lower | Better for weight-critical parts |
| Cost drivers | Lower melt energy, long die life, great cosmetics | Lightweight, structural stiffness, hotter process |
How to choose a Zamak grade
Start your RFQ with Zamak 3 unless a design requirement pushes you elsewhere.
Bump to Zamak 4 when you want a touch more strength but don’t want to sacrifice castability.
Choose Zamak 5 when parts are small yet need real bite—brackets, levers, lock arms.
If the geometry is thin-walled or you’re chasing extremely crisp detail, Zamak 7 is often the smoothest running grade.
Reserve Zamak 2 for long-term load and wear where creep matters more than elongation.
How to design Zamak die-cast parts for plating and accuracy
Zamak rewards uniform walls and gentle transitions. Keep typical wall stock in the 1.0–2.5 mm range unless we validate thinner with flow/thermal analysis. Blend ribs and bosses into walls with radii; avoid knife edges that polish poorly.
Provide sensible draft—~0.5–1.0° on cosmetic pulls—to reduce scuffing during ejection and to minimize polishing passes. Plan datums so that any post-cast machining is short and localized. On plated parts, let the gating system and ejector layout live on non-critical faces; you’ll get a cleaner polish, faster.
Zamak finishing, plating and paint options
One reason buyers specify Zamak is finish freedom. Highly polished surfaces can be copper-nickel-chrome plated for mirror aesthetics; matte and satin looks are easy with nickel or bead-blast + clear coat.
Powder coating and wet paint both adhere well when we use the right pretreatments. If you’re targeting aggressive salt spray, we’ll recommend base-metal polishing grades, strike steps, and thicknesses for each layer in the stack so the surface stays clean after months of exposure.
Zamak quality and compliance for buyers
Commercial Zamak alloys are routinely supplied within ASTM/EN/ISO chemistry limits and can meet RoHS and REACH expectations when ordered from qualified producers.
If your program needs IMDS, material declarations, or PPAP-level documentation, we can provide those alongside CT or X-ray data on first-article parts. It’s also normal to agree on plating test panels and salt-spray criteria up front so the finish gets evaluated the same way your customers will see it.
Procurement checklist (use in your RFQ)
- Target grade and acceptable alternates
- Finish class (e.g., mirror chrome, satin nickel, powder) and polishing level
- Critical datums and any post-cast machining
- Dimensional tolerances and cosmetic acceptance criteria
- Required documents (RoHS, REACH, IMDS, PPAP, CT/X-ray, salt spray)
Ready to evaluate Zamak for your part?
Upload your CAD and tell us the grade and finish you’re aiming for. We’ll return a short DFM with gating/venting strategy, polishing plan, and a cost/lead-time estimate so you can compare Zamak with aluminum on numbers—not guesswork.
FAQ
Is Zamak magnetic?
No. Zinc-based alloys are generally non-magnetic, which is helpful around sensors or compasses.
Can Zamak be welded or brazed after casting?
Fusion welding is not recommended. Some low-temperature brazing/soldering methods exist for non-structural repairs, but design-for-assembly is the better approach.
Does Zamak contain lead?
Commercial die-casting grades are formulated to meet RoHS/REACH-type limits when specified; ask for certificates with each lot.
Is Zamak suitable for jewelry or skin contact?
With appropriate alloy control and nickel-free plating stacks, Zamak can meet many brand policies. If your product is worn on skin, share your standard so we can match the finish system.
Can Zamak be recycled?
Yes. Zinc alloys recycle efficiently. Many foundries run certified recycled content while still meeting chemistry and cleanliness requirements.
