Die casting — injecting molten metal under high pressure into a precision-machined steel mold — is the dominant manufacturing process for producing complex metal parts at scale. From the aluminum transmission housing in your car to the zinc door handle on your office and the magnesium laptop frame on your desk, die-cast components are everywhere.
Three base metals dominate the global die casting market — but the real engineering decision isn’t just “which metal.” It’s which alloy within that metal family meets your specific requirements for tensile strength, elongation, corrosion resistance, surface finish, and cost-per-part at your production volume.
Key Takeaways
- Aluminum Die Casting (A380 / A383 / ADC12): The Volume Leader. Accounts for roughly 70-85% of die casting production by weight (industry estimates). Best strength-to-cost ratio among the three. Dominant in automotive powertrain, structural, and thermal management applications. Key trade-off: higher melting temperature (~660°C) increases energy cost and die wear compared to zinc.
- Zinc (Zamak 3 / Zamak 5 / ZA-27): The Precision Specialist. Lowest melting point (~385-420°C) enables fastest cycle times (15-30 seconds) and longest die life (often 1M+ shots). Achieves tighter dimensional tolerances (±0.02mm) than aluminum or magnesium. Dominant in consumer hardware, locks, and small connectors. Key trade-off: density is ~2.5× higher than aluminum — weight-sensitive applications need aluminum or magnesium.
- Magnesium (AZ91D / AM60B): The Lightweight Specialist. Density 1.81 g/cm³ — roughly 30% lighter than aluminum. Best vibration damping of the three. Growing in EV structural components and handheld electronics. Key trade-off: highest material cost ($3-6/kg), requires SF₆ or alternative cover gas during melting, more complex foundry safety protocols.
Three Metals Used in Die Casting
Answer three questions to narrow your metal choice, then refer to the detailed profiles below:
| If Your Priority Is | First Choice | Second Look | Why |
|---|---|---|---|
| Lowest cost per part at volume | Zinc (Zamak 3) | Aluminum (A380) | Fastest cycle + lowest die wear = lowest amortized cost |
| Lightest weight | Magnesium (AZ91D) | Aluminum (thin-wall) | Mg is ~30% lighter than Al; thin-wall Al can close gap |
| Highest strength-to-weight | Magnesium (AZ91D) | Aluminum (A380) | Mg excels; Al is close second for non-weight-critical |
| Tightest tolerances / finest detail | Zinc (Zamak 5) | Magnesium | Low melt temp + high fluidity = ±0.02mm achievable |
| Best corrosion resistance | Aluminum (ADC12) | Zinc (Zamak 3) | Al naturally passivates; Zn good with plating; Mg needs coating |
| Best thermal conductivity | Aluminum | — | 150-170 W/m·K vs Mg 90-115 and Zn 118-140 |
| Best electrical conductivity | Copper/Brass | Zinc | None of the “big 3” excel at conductivity; Cu is the specialist |
| Best vibration damping | Magnesium | Zinc | Mg’s hexagonal crystal structure absorbs vibration energy |
| Best for electroplating / finishing | Zinc | Aluminum (anodized) | Zn accepts direct Cu-Ni-Cr plating; Al needs anodizing or conversion coating |
Alloy-Level Comparison — Key Grades at a Glance
| Property | Al A380 | Al ADC12 | Zn Zamak 3 | Zn Zamak 5 | Mg AZ91D | Mg AM60B |
|---|---|---|---|---|---|---|
| Density (g/cm³) | 2.68 | 2.68 | 6.65 | 6.55 | 1.81 | 1.80 |
| Tensile Strength (MPa) | 310-370 | 250-320 | 320-380 | 380-420 | 240-280 | 220-260 |
| Yield Strength (MPa) | 270-300 | 190-230 | 240-300 | 300-350 | 200-230 | 130-160 |
| Elongation (%) | 1-4 | 1-3 | 2-5 | 3-6 | 3-5 | 6-10 |
| Hardness (Brinell) | 75-85 | 70-80 | 95-110 | 100-120 | 60-75 | 55-65 |
| Melting Range (°C) | 540-595 | 520-585 | 380-387 | 380-386 | 470-595 | 525-620 |
| Thermal Cond. (W/m·K) | 150-170 | 130-150 | 118-140 | 130-150 | 90-115 | 60-65 |
| Corrosion Resistance | Good | Excellent | Excellent | Good | Moderate | Moderate |
| Typical Die Life (shots) | 80K-150K | 80K-150K | 500K-1M+ | 500K-1M+ | 60K-120K | 60K-120K |
| Reference Standard | ASTM B85 | JIS H5302 | ASTM B86 | ASTM B86 | ASTM B94 | ASTM B94 |
Metal Comparison and Selection
Engineering Properties — When Numbers Drive Decisions
Mechanical properties alone don’t tell the full story. The table below pairs what the numbers mean with what engineers actually care about in production:
| Property | Al (A380) | Zn (Zamak 3) | Mg (AZ91D) | What Engineers Care About |
|---|---|---|---|---|
| Density (g/cm³) | 2.68 | 6.65 | 1.81 | Drives part weight → system-level fuel/range/packaging impact |
| UTS (MPa) | 310-370 | 320-380 | 240-280 | Peak load before fracture; Zn surprising here — often overlooked |
| Yield (MPa) | 270-300 | 240-300 | 200-230 | Permanent deformation threshold; Al leads for structural use |
| Elongation (%) | 1-4 | 2-5 | 3-5 | Critical for impact/drop resistance; higher = more energy absorption before fracture |
| Hardness (BHN) | 75-85 | 95-110 | 60-75 | Scratch and wear resistance; Zn significantly harder than Al/Mg |
| Thermal Cond. | 150-170 | 118-140 | 90-115 | Heat sink / LED housing / EV battery tray: Al is the clear choice |
| Melting Range (°C) | 540-595 | 380-387 | 470-595 | Lower range = faster cycle + longer die life → Zn dominates |
| Die Life (shots) | 80K-150K | 500K-1M+ | 60K-120K | Tooling amortization: Zn dies last 5-10× longer than Al/Mg |
Cost at Production Volume — 2025 Estimates (Southeast Asia)
Note: Prices are indicative mid-2025 ranges for Southeast Asian foundries. Request current quotes for your specific alloy, geometry, and volume.
| Cost Factor | Al (A380) | Zn (Zamak 3) | Mg (AZ91D) |
|---|---|---|---|
| Raw Material ($/kg) | $2.50-3.50 | $2.80-3.80 | $3.50-5.50 |
| Cycle Time (seconds) | 30-90 | 15-30 | 20-35 |
| Die Cost (1-cavity) | $5K-25K | $3K-12K | $7K-18K |
| Die Life (shots) | 80K-150K | 500K-1M+ | 60K-120K |
| Tooling Amortized ($/part, 100K) | $0.05-0.25 | $0.003-0.02 | $0.06-0.30 |
| Energy Cost ($/part, est.) | $0.30-0.80 | $0.10-0.30 | $0.40-1.00 |
| Estimated Total ($/part, 100K) | $3.00-5.50 | $1.50-3.00 | $4.50-7.00 |
| Key Cost Driver | Energy + cycle time | Material price stability | Material cost + safety compliance |
Step-by-Step Metal Selection Workflow
- Define the must-have performance requirements. What’s the minimum tensile strength? What’s the maximum acceptable weight? Will the part see sustained temperatures above 120°C? (If yes, zinc is out — creep becomes significant above 100°C.)
- Assess production volume. Under 10,000 parts/year? Zinc’s lower tooling cost dominates. Over 100,000 parts/year? Aluminum’s lower material cost may offset slower cycle time. Over 500,000 parts/year? Run full TCO analysis including energy and tooling amortization.
- Evaluate the operating environment. Outdoor marine exposure? Aluminum (A380 with coating) or well-plated zinc. Constant vibration? Magnesium (AZ91D or AM60B). Electrical conductivity needed? Consider brass or copper instead — none of the “big three” excel here.
- Check finishing requirements. Mirror chrome finish? Zinc accepts direct Cu-Ni-Cr plating beautifully. Brushed or anodized look? Aluminum. Powder coating over any? All three work, but surface prep differs.
- Verify regulatory compliance. Automotive? Confirm ELV compliance (no hexavalent chromium in passivation). Electronics? RoHS and REACH. EU market after 2026? Magnesium foundries must plan for SF₆ phase-out under EU F-gas regulation 2024/573.
- Prototype in the winning metal. Before committing to production tooling ($5K-$25K), order rapid prototype castings in your selected alloy. Test fit, function, and finish. Adjust alloy grade if needed — e.g., A380 → A383 for better die-filling on thin walls, or Zamak 3 → Zamak 5 for higher tensile requirements.
FAQ
What industries use aluminum, zinc, and magnesium die casting?
Many companies use these metals for special parts. Car makers, electronics, phone, and medical equipment companies use them. They need strong and exact pieces for their products.
Why do factories choose aluminum for die casting?
Factories pick aluminum because it is strong and light. It does not rust easily. These things help make parts that last and work well.
Can MORELUX provide custom die-casting solutions?
MORELUX makes custom die-cast parts for many companies. They use new machines and tools to fit each project’s needs.