What are the materials for Select Zinc Alloy and Prepare Material?

The most common zinc die casting alloys are from the Zamak family and ZA (Zinc-Aluminum) family:

Zamak Alloys

ZA (Zinc-Aluminum) Alloys

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