Zinc and aluminum are the two most common die casting metals, and the choice between them comes down to a short list of questions: how heavy can the part be, how hot does it get, how many do you need, and what does the surface have to look like. Zinc wins on precision, thin walls, tooling life, and small-part economics. Aluminum wins on weight, heat resistance, and large structural parts. Everything else is detail, and the details are below.
We run both processes in-house, so this comparison comes from daily production rather than theory. It covers the full property comparison, real cost behavior, the scenarios where each metal wins, and a decision framework you can apply to your own part. For the process background, see our pages on zinc die casting and aluminum die casting.
Zinc vs Aluminum Die Casting at a Glance
| Property | Zinc (Zamak 3 / 5) | Aluminum (A380 / ADC12) |
|---|---|---|
| Density | 6.6 g/cm³ | 2.7 g/cm³ |
| Melting point | 380–420 °C | 580–660 °C |
| Casting process | Hot chamber | Cold chamber |
| Tensile strength | 283–331 MPa | ~320 MPa |
| Strength-to-weight | Low | Excellent |
| Minimum wall | 0.3–0.5 mm | ~1.0 mm |
| As-cast tolerance | ±0.025–0.05 mm | ±0.05–0.10 mm |
| Die life | 500K–1M+ shots | 100K–150K shots |
| Cycle time | Fastest (3–8 s on small parts) | Moderate |
| Continuous service temperature | ≤80 °C | ~200 °C |
| Typical finish | Chrome plating, mirror polish, powder coat | Anodizing, powder coat, shot blast |
| Best for | Small precision parts, decorative hardware, high volumes | Structural parts, housings, heat-sensitive and weight-sensitive applications |
The sections below explain what each row means in practice.
Weight and Strength
At 6.6 g/cm³, a zinc part weighs about 2.4 times as much as the same geometry in aluminum. Absolute tensile strength is closer than most buyers expect: Zamak 3 delivers 283 MPa as cast, Zamak 5 reaches 331 MPa, and A380 aluminum sits around 320 MPa. Zinc also offers better impact strength and elongation than standard aluminum die casting alloys, which is why it survives drop tests and press-fit assembly so well.
Per unit of weight, the picture flips. Aluminum’s strength-to-weight ratio is roughly four times better, and that single number drives most material decisions in automotive and anything handheld or moving. Zinc also loses strength above 80 °C in continuous service, while aluminum die castings hold up to around 200 °C. Any part near a motor, engine, or heating element belongs in aluminum.
Production Economics: Tooling, Cycle Time, and Cost
Zinc’s low melting point is gentle on tool steel. A zinc die routinely exceeds 1 million shots, five to ten times the 100,000–150,000 shots typical of an aluminum die, because aluminum at 650 °C and above attacks the die surface with far more thermal load. Zinc dies can also run in more economical pre-hardened steels on smaller tools, so the tooling invoice itself is often lower.
Cycle time follows the same logic. Hot chamber machines pump zinc directly from the melt bath, with no ladling step, and the metal solidifies fast. Small zinc parts come off the machine every 3–8 seconds, and zinc cycle rates run 150–200% higher than aluminum on comparable parts. Aluminum’s cold chamber process adds a ladling step and a longer solidification wait on every shot.
Material cost favors aluminum per kilogram, and aluminum alloys are largely produced from recycled feedstock. Zamak is a high-purity material and costs more per kilo. But part cost is not material cost. A zinc part typically casts thinner walls, needs no machining to reach final dimensions, cycles faster, and amortizes tooling over far more shots. For small components, the finished zinc part frequently costs less than its aluminum equivalent. The crossover moves toward aluminum as parts get bigger and heavier. We break the numbers down in our zinc die casting cost and aluminum die casting cost guides.
Precision and Design Freedom
Zinc’s fluidity is the best of any die casting metal. It fills walls down to 0.3–0.5 mm, holds tolerances of ±0.025–0.05 mm on small features (about 20–30% tighter than aluminum), casts smaller and deeper cored holes, and needs less draft. Many zinc parts ship net-shape with zero machining, which removes a whole cost layer from the project.
Zinc castings are also pressure-tight far more often than aluminum ones. Aluminum castings used in fluid-handling applications normally need impregnation to seal micro-porosity; zinc parts usually do not. For valves, pump components, and sealed housings, that difference alone can settle the material question. Design rules for both metals are covered in our zinc die casting design guide.
One more design point matters for buyers consolidating parts. Zinc’s strength and castability let engineers combine several stamped or machined pieces into one casting with cast-in threads, bearings, or shafts. That trick works in aluminum too, but zinc’s tighter as-cast dimensions usually make the consolidation easier to pull off without extra machining.
Surface Finishing
Zinc is the standard substrate for decorative plating. Its low-porosity surface takes a copper strike, nickel, and chrome to a mirror finish, and it also accepts powder coating, paint, and passivation. This is why visible hardware — hinges, handles, hooks, knobs — is overwhelmingly zinc.
Aluminum cannot take conventional decorative plating easily, but it anodizes well and powder coats well. Anodizing gives a hard, integral finish suited to industrial and outdoor parts, though high-silicon casting alloys anodize to a gray tone rather than a bright one. Our guide to anodizing cast aluminum covers what to expect by alloy.
When to Choose Zinc Die Casting
- Small to medium parts, typically under 3 kg, produced at high volume
- Thin walls below 1 mm or complex geometry with fine detail
- Tight as-cast tolerances that should avoid secondary machining
- Decorative finishes such as mirror chrome plating
- Impact resistance and press-fit or insert assembly
- Pressure-tight fluid-handling components
- Very long production runs where die life drives unit cost
When to Choose Aluminum Die Casting
- Weight-sensitive parts: automotive, aerospace, handheld devices
- Operating temperatures above 80 °C, including motor-adjacent components
- Large structural parts and housings over 3 kg
- Heat dissipation applications such as heat sinks and LED housings
- Outdoor exposure where natural corrosion resistance matters
- Parts that will be anodized
A Simple Decision Framework
- Check temperature first. Continuous service above 80 °C eliminates zinc. This is the only hard filter in the list.
- Check weight sensitivity. If the part moves, flies, or carries a fuel or battery budget, choose aluminum.
- Check size. Over roughly 3 kg, aluminum is usually the only practical option.
- Check the surface requirement. Mirror chrome or decorative plating points to zinc; anodizing points to aluminum.
- Check volume. Very high volumes amplify zinc’s die life and cycle speed advantages.
- Price both if nothing above decides it. For small parts, quote both metals — zinc often wins on finished-part cost even with pricier raw material.
Real Project Examples
Refrigerator door hinge — zinc. A hinge is small, load-bearing, cycled daily, and on a visible surface. We produce these in Zamak 5 for the extra strength from its 1% copper content, in 8-cavity hot chamber molds, finished with mirror polishing and chrome plating. Zinc wins on every row that matters here: strength, surface, cycle speed, and cost at volume.
Washing machine spider — aluminum. The spider connects the drum to the bearing shaft, sees hot water and sustained mechanical load, and benefits from low rotating mass. We cast it in ADC12 aluminum on cold chamber machines, then machine the bearing bore to tolerance. Zinc would fail the temperature and weight filters immediately. See our washing machine spider page for the part details.
Electrical junction box — aluminum. An outdoor sealed enclosure needs corrosion resistance, heat dissipation, and low weight on a pole or wall. Aluminum with powder coating covers all three. The same box in zinc would work electrically but carry 2.4 times the weight for no functional gain.
Get a Material Recommendation with Your Quote
Meituo runs hot chamber zinc and cold chamber aluminum die casting lines in one factory, with mold design, CNC machining, plating, and assembly under the same roof. We have no incentive to push one metal over the other, because we produce both. Send your drawing through our contact page and our engineers will come back with a material recommendation, DFM feedback, and a quotation within 48 hours.
