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Should I use Zamak 3 or Zamak 5?
Zamak 3 is the default zinc die casting alloy in North America, with the best long-term dimensional stability and slightly more ductility. Choose Zamak 5 when the part carries load or torque: about 1% copper raises tensile strength roughly 17%, to 48 ksi (331 MPa) from 41 ksi (283 MPa), and improves creep resistance. Both cast and plate the same way.
Zinc Zamak 3
Zinc Zamak 5
By the numbers
Priced on the same representative part: housing, die casting, 5,000 pcs.
Tensile strengthMPa
Zamak 3
283
Zamak 5
331
Yield strengthMPa
Zamak 3
221
Zamak 5
269
Densityg/cm³
Zamak 3
6.6
Zamak 5
6.6
Max service temp°C
Zamak 3
100
Zamak 5
100
Elongation%
Zamak 3
10
Zamak 5
7
Raw material cost$/kg
Zamak 3
4
Zamak 5
4.2
Which should you pick?
Pick Zamak 3 when
- Dimensions must stay stable over years of service
- Loads are light, as on trim, handles, housings and badges
- The part is staked or swaged after casting and needs the extra ductility
- It is a cosmetic plated part, where Zamak 3 is the common base
Pick Zamak 5 when
- The part carries sustained load, torque or clamp force
- Bosses and threads see preload
- Wear surfaces benefit from 91 HB versus 82 HB
- It is a light-duty gear, lever or lock part
Key differences
| Zamak 3 | Zamak 5 | |
|---|---|---|
| Copper content | No intentional copper | About 1% |
| Creep resistance | Lower | Better; preferred for loaded bosses and threaded joints |
| Long-term dimensional stability | Best of the Zamak alloys | More dimensional growth over years |
| Post-cast staking or swaging | More forgiving | Less forgiving |
| Regional default | North American standard | Common in Europe and for loaded parts |
| Casting and finishing | Hot-chamber; plates with copper-nickel-chrome | Same process and finishes |
| Metal cost | Baseline | Slightly higher |
Questions
Is Zamak 5 better than Zamak 3?
Stronger, not better across the board. Zamak 5 runs about 17% higher tensile strength and resists creep better. Zamak 3 is slightly more ductile and holds its dimensions better over years. Choose on load: light-duty parts stay Zamak 3.
Can a Zamak 3 die run Zamak 5?
Usually. Both alloys run in hot-chamber machines and are commonly cast in the same dies, so a switch is typically a material change and requalification rather than a new tool. Confirm with the die caster and rerun first article inspection.
When should I look past Zamak 5?
When load, wear or temperature exceed what it handles. ZA-8 is stronger and more creep resistant and still casts in hot-chamber machines. For higher-load gears, powder metal FC-0208 or FN-0205 is the better call; for heat, use aluminum.
Does Zamak contain lead?
No intentional lead. ASTM B86 caps lead at a few thousandths of a percent in Zamak castings, far below the 0.1% RoHS limit.
Try both on your part.
The builder prices the same geometry in every suitable process and material, with DFM for each.