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Should I die cast in aluminum or zinc?
Choose Zamak 3 zinc for small, detailed or plated parts: it casts walls down to about 0.030 in (0.75 mm), holds tighter tolerances as cast, and its dies often last over 1,000,000 shots versus 100,000–150,000 for aluminum. Choose A380 aluminum for larger housings, weight-sensitive parts, and service above about 212 °F (100 °C). Zinc parts weigh about 2.4× more.
Aluminum A380 (die cast)
Zinc Zamak 3
By the numbers
Priced on the same representative part: housing, die casting, 5,000 pcs.
Tensile strengthMPa
A380
324
Zamak 3
283
Yield strengthMPa
A380
159
Zamak 3
221
Densityg/cm³
A380
2.71
Zamak 3
6.6
Max service temp°C
A380
150
Zamak 3
100
Elongation%
A380
3.5
Zamak 3
10
Raw material cost$/kg
A380
3
Zamak 3
4
Which should you pick?
Pick A380 when
- The part is large or weight-sensitive, such as a housing or chassis
- Service runs above about 212 °F (100 °C)
- Bolted joints or bosses carry sustained preload
- Powder coat, e-coat or paint is the planned finish
Pick Zamak 3 when
- The part is small and detailed, with walls near 0.030 in (0.75 mm)
- It gets decorative chrome, nickel or brass plating
- Lifetime volume is high enough that die life drives cost
- Tolerances must be met as cast with little machining
Key differences
| A380 | Zamak 3 | |
|---|---|---|
| Casting process | Cold-chamber; 30–120 second cycles | Hot-chamber; 5–30 second cycles |
| Die life | About 100,000–150,000 shots | Often 1,000,000+ shots |
| Minimum wall | 0.040–0.080 in (1.0–2.0 mm) | 0.020–0.040 in (0.5–1.0 mm) |
| Draft | About 1–2° | About 0.5–1° |
| Finishing | Powder coat, e-coat, paint or chem film; anodizes gray and blotchy | Best plating base for chrome and nickel; also powder coat and paint |
| Creep under load | Holds strength to about 300 °F (150 °C) | Creeps under sustained load, faster above 120 °F (50 °C) |
| As-cast surface | Ra about 32–125 µin (0.8–3.2 µm) | Smoother than aluminum, which helps plating |
Questions
Is zinc die casting cheaper than aluminum?
Often for small parts. Faster hot-chamber cycles and dies that last 1,000,000+ shots offset zinc's weight. As parts get larger, zinc's 2.4× density raises metal cost per part enough that aluminum usually wins.
Which is stronger, A380 or Zamak 3?
It depends on the measure. A380 has higher tensile strength, about 47 ksi (324 MPa) versus 41 ksi (283 MPa), but Zamak 3 has higher yield, about 32 ksi (221 MPa) versus 23 ksi (159 MPa), and 10% elongation versus 3.5%. Under heat or sustained load, zinc's creep makes aluminum the safer choice.
Can die cast aluminum be anodized?
Not well. A380's 7.5–9.5% silicon and 3–4% copper produce a thin, gray, uneven coating. Powder coat or paint cosmetic parts, and use chem film for conductivity and corrosion protection.
What temperature can zinc die castings handle?
Plan for continuous service below about 212 °F (100 °C). Zinc alloys creep under sustained load even near room temperature, and faster above 120 °F (50 °C). For hot or preloaded parts, use aluminum.
Try both on your part.
The builder prices the same geometry in every suitable process and material, with DFM for each.