How does zinc alloy die casting compare to aluminum in strength and cost?

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Zinc is stronger per unit volume than aluminum but heavier (density 6.6 vs 2.7 g/cm3). Zinc offers 3-10x higher ductility, better impact strength, and 3-5x longer die life. Aluminum offers 3x better strength-to-weight ratio and higher service temperatures. Cost-wise, zinc per-part cost is typically 10-30% lower for small parts due to faster cycle times and longer die life. For large parts, aluminum's lower density gives it a weight-based cost advantage.

Strength Comparison

Tensile strength: ZAMAK 3: 283 MPa, ZAMAK 5: 331 MPa, Aluminum A380: 320 MPa. Comparable. Yield strength: ZAMAK 3: 221 MPa, A380: 160 MPa. Zinc is stronger in yield. Elongation: ZAMAK 3: 10%, ZAMAK 5: 7%, A380: 1-3%. Zinc is 3-10x more ductile. Impact strength (Izod): ZAMAK 3: 58 J/m, A380: 3-5 J/m. Zinc absorbs 10-20x more impact energy. Hardness: ZAMAK 3: 82 HB, A380: 80 HB. Similar.

Cost Comparison

Die life for zinc: 800,000-1,000,000 shots. For aluminum: 100,000-300,000 shots. Zinc's longer die life spreads tooling cost over more parts. Zinc cycle time is typically 20-40% faster (lower melting point = faster solidification). Zinc melting temperature (385-420°C) vs aluminum (660-680°C) means lower energy costs. Material cost: ZAMAK $2.50-3.50/kg vs A380 $3.00-4.50/kg. For small parts under 200g, zinc is 10-30% cheaper per part at equivalent volumes.

Application Guidance

Choose zinc when: part weight is not critical, thin walls are needed (0.3-0.8mm), impact resistance is important, ductility is required for bending or crimping, or very long die life is desired. Choose aluminum when weight is critical, the part is large, operating temperatures exceed 120°C, or pressure tightness is required (aluminum can be impregnated).

Why Choose SOMI Custom Parts

At SOMI Custom Parts, we offer both zinc and aluminum die casting, allowing us to recommend the optimal material for each application. We provide a complete cost comparison analysis including material cost, tooling cost amortization, cycle time, and finishing costs. Our engineers can help you decide -- and if needed, we can redesign your part for the more advantageous material.

Case Study

An automotive supplier had a small (50g) latch component in aluminum A380 that was experiencing 5% breakage during assembly due to the alloy's low ductility. SOMI converted the part to ZAMAK 5, increasing elongation from 2% to 7%. The zinc part passed assembly testing with zero breakage. Cycle time decreased by 25%, die life was projected at 800,000 shots vs 200,000 for aluminum. Part cost decreased by 18%.

Industry Data

Zinc die casting alloys offer the highest ductility of any common die casting material. The elongation of ZAMAK 3 (10%) is comparable to many wrought aluminum alloys, making it the preferred choice for parts requiring forming or bending after casting (NADCA, 2025). Zinc's lower melting point also reduces greenhouse gas emissions by approximately 40% per part compared to aluminum casting.