What is Zamak 3 material?
Zamak 3 (also seen as ZA3, ZP3) is the world’s most widely specified zinc-based die-casting alloy. It’s built on zinc with ~4% aluminum and a trace of magnesium to stabilize the structure.
The result is a metal that casts quickly at low temperature, reproduces fine details, and accepts premium decorative finishes such as Cu/Ni/Cr chrome plating. Because it balances strength, ductility, castability and cost, Zamak 3 is the default starting point for most zinc die-cast programs.
What is the chemical composition of Zamak 3?
A small change in chemistry has a big effect on casting behavior and finish quality. Zamak 3 keeps copper extremely low, favoring ductility and easy polishing.
Typical Zamak 3 composition Table
| Element | Aluminum (Al) | Magnesium (Mg) | Copper (Cu) | Iron (Fe) | Zinc (Zn) |
|---|---|---|---|---|---|
| Range | 3.5 – 4.3 | 0.02 – 0.06 | ≤ 0.05 | ≤ 0.075 | Balance |
Why it matters
- Aluminum lifts strength and hardness while keeping melting temperature low.
- Magnesium stabilizes the microstructure and resists intergranular corrosion.
- Very low copper preserves ductility and makes mirror-grade finishing easier.
- Clean melt practice (dross control, Fe limits) protects plating appearance.
How strong is Zamak 3?
Mechanical properties vary with section thickness, die temperature, and porosity control. The ranges below represent typical high-quality pressure die castings.
Zamak 3 mechanical properties Table
| Property | Typical Range | Notes |
|---|---|---|
| Ultimate tensile strength | 250 – 300 MPa | Thinner, well-fed sections trend higher |
| Yield strength | 190 – 240 MPa | Sensitive to porosity and die temperature |
| Elongation (A50) | 5 – 10% | Good for snap-fits/light forming |
| Brinell hardness | 80 – 100 HB | Increases slightly after aging |
| Fatigue strength (10⁷ cycles) | ~95 MPa | Geometry & surface finish dependent |
Buyer takeaway: Zamak 3 combines enough strength for everyday hardware with the ductility needed for clean deburring, polishing, and small press fits.
What are the physical properties of Zamak 3?
Zamak 3’s low melting point and high fluidity are the reason zinc tools last so long and cycles are so fast.
Zamak 3 physical data Table
| Property | Typical Value | Why it helps |
|---|---|---|
| Density | ~6.6–6.7 g/cm³ | “Solid” hand-feel; excellent damping |
| Melting range | ~380–390 °C (716–734 °F) | Low thermal shock → long die life |
| Thermal conductivity | ~110–120 W/m·K | Aids heat extraction and short cycles |
| Coefficient of thermal expansion | ~26–28 µm/m·K | Allowance for fit in assemblies |
| Electrical resistivity | ~6–7 µΩ·m | Useful for shielding/EMI covers |
Is Zamak 3 good for die casting?
Yes—this is why it’s the baseline zinc alloy.
Casting behavior in practice
- High fluidity fills thin ribs, logos, and small bosses; flash control is straightforward.
- Low melt temperature reduces die erosion and extends tool life.
- Predictable shrinkage supports tight as-cast dimensions when gating/vents are correct.
- Typical risks (gas porosity, cold shuts) are mitigated with balanced runners, vacuum assist for deep pockets, and robust vent/overflow design.
How does Zamak 3 compare with Zamak 5 and Zamak 7?
Zamak 5 adds copper for strength and hardness; Zamak 7 lowers magnesium for extra ductility and fluidity.
Zamak 3 vs Zamak 5 vs Zamak 7 Table
| Feature | Zamak 3 | Zamak 5 | Zamak 7 |
|---|---|---|---|
| Strength/Hardness | ●●○ | ●●● | ●●○ |
| Ductility | ●●● | ●●○ | ●●● |
| Thin-wall castability | ●●● | ●●○ | ●●● |
| Polishing/plating | Excellent | Very good | Excellent |
| Typical use | Default choice | Small strong brackets, levers | Very thin or intricate parts |
Rule of thumb
- Start with Zamak 3.
- Move to Zamak 5 if you need a noticeable strength bump and are OK with slightly lower ductility.
- Choose Zamak 7 for the cleanest flow into thin sections or when you want a little post-forming.
How does Zamak 3 compare with aluminum die casting?
- Weight: Aluminum is ~2.7 g/cm³ vs Zamak ~6.7 g/cm³. Pick aluminum where weight is critical.
- Finish: Zamak enables mirror chrome and deep luster; aluminum favors anodize/paint.
- Die life & cycle time: Zamak’s lower temperature improves both.
- Hot service: Aluminum tolerates higher sustained temperatures.
When buyers choose Zamak 3: cosmetic surfaces must be perfect, lettering is tiny, and cycle time + die life drive the economics.
Does Zamak 3 plate and paint well?
Absolutely. The alloy polishes uniformly and accepts Cu/Ni/Cr stacks (mirror or satin). For paint or powder, proper pretreatment (degrease, activate, conversion coat) gives excellent adhesion. For salt-spray targets, we’ll define the strike and nickel thicknesses and mask any functional bores so plating does not close critical fits.
How should I design for Zamak 3 die casting?
Walls & features
- Typical wall stock 1.0–2.5 mm; we can validate thinner by flow/thermal analysis.
- Blend ribs and bosses with generous radii; avoid knife edges that polish poorly.
- Provide 0.5–1.0° draft on cosmetic pulls to reduce scuffing and polishing time.
Datums & cosmetics
- Put gates, vents, ejectors on non-show faces.
- Use clear datums to minimize post-cast machining on show surfaces.
- For plated parts, plan a polishing spec and visual acceptance limit up front.
What tolerances can I expect?
Typical zinc die-casting tolerance bands are tight for as-cast parts. As a planning guide:
- Linear dimensions under 25 mm: ±0.05–0.08 mm
- 25–100 mm: ±0.08–0.12 mm
- Over 100 mm: ±0.2 mm (design and gating dependent)
Flatness improves with rib strategy and uniform walling; selective face machining is used only where needed.
What standards and equivalents cover Zamak 3?
You’ll see Zamak 3 specified under common systems such as ASTM, EN/ISO, and regional equivalents from material suppliers. We supply RoHS/REACH declarations, IMDS, and PPAP/FAI on request so your quality team has full traceability.
Where is Zamak 3 used?
Zamak 3 is chosen wherever feel + finish matter: furniture/architectural hardware, appliance knobs and bezels, lock bodies, cosmetic housings, consumer-electronics enclosures, badgework, and small mechanisms that need stable dimensions and a premium surface.
Does Zamak 3 resist corrosion?
Base Zamak 3 is similar to other zinc alloys; for demanding environments, plated or coated finishes dramatically improve performance. Watch galvanic couples (e.g., stainless fasteners) and specify insulating washers or compatible finishes where needed.
Quality controls we apply for Zamak 3 parts
- Melt analysis per heat; chemistry certificates with each lot.
- CT/X-ray sampling for porosity in critical sections.
- SPC on CTQ dimensions; leak/torque tests for assemblies.
- First-article documentation (FAI/PPAP/IMDS) aligned with your SOP.
RFQ checklist for Zamak 3 buyers
- Target grade (Zamak 3) and acceptable alternates (5/7 if needed)
- Finish class (mirror chrome, satin nickel, powder/paint) + polishing spec
- Critical datums/tolerances and any selective machining
- Cosmetic acceptance criteria and salt-spray targets (if plated)
- Annual volume, packaging, compliance docs (RoHS/REACH/IMDS)
