Shenzhen Alu Rapid Prototype Precision Co., Ltd.
Industry News
Selecting a Zinc Alloy
The most common zinc die casting alloys are from the Zamak family and ZA (Zinc-Aluminum) family:
Zamak Alloys
Alloy | Composition | Key Characteristics |
Zamak 2 | Zn + 4% Al + 2.7% Cu + 0.035% Mg | Highest strength & hardness in Zamak family |
Zamak 3 | Zn + 4% Al + 0.035% Mg | Most widely used; best balance of properties |
Zamak 5 | Zn + 4% Al + 1% Cu + 0.035% Mg | Stronger than Zamak 3; good creep resistance |
Zamak 7 | Zn + 4% Al + 0.010% Mg (ultra-pure) | Best ductility and surface finish |
ZA (Zinc-Aluminum) Alloys
Alloy | Composition | Key Characteristics |
ZA-8 | Zn + 8% Al + 1% Cu | Good strength; hot chamber castable |
ZA-12 | Zn + 12% Al + 1% Cu | High strength & hardness |
ZA-27 | Zn + 27% Al + 2% Cu | Highest strength zinc alloy; lightweight |
Preparing the Material
Material preparation involves several steps to ensure casting quality:
1. Sourcing & Verification
Use certified ingots from reputable suppliers
Verify alloy grade matches specification (e.g., ASTM B240)
Check material certifications and composition reports
2. Melting
Zinc alloys melt at relatively low temperatures (380–420°C / 716–788°F for Zamak)
Use a gas-fired or electric resistance furnace
Maintain precise temperature control — overheating causes:
Aluminum and magnesium loss (evaporation/oxidation)
Iron pickup from the furnace/pot
Degraded mechanical properties
3. Fluxing & Drossing
Add flux to the melt to prevent oxidation
Skim off dross (oxidized surface layer) regularly
Dross removal is critical to avoid inclusions in castings
4. Alloying Adjustments
Periodically test melt composition using spectrographic analysis
Adjust chemistry if elements are out of range
Magnesium is especially prone to loss and often needs topping up
5. Contamination Control
Keep iron content below 0.1% — iron causes brittleness
Avoid lead, cadmium, and tin contamination (causes intergranular corrosion)
Use clean, dry scrap only — moisture causes violent spattering and porosity
6. Temperature Holding
Hold molten metal at the correct holding temperature
Too hot = metal degradation
Too cool = premature solidification, misruns, cold shuts
Key Material Selection Criteria
When choosing which zinc alloy to use, consider:
Strength requirements → Zamak 2, ZA-12, or ZA-27
Best surface finish → Zamak 3 or Zamak 7
Thin wall / complex geometry → Zamak 3 or Zamak 7
Cost efficiency → Zamak 3 (most economical and widely available)
Higher temperature use → ZA alloys