Die Casting Zinc Alloys

‌Physical Properties and Main Grades of Die-Casting Zinc Alloys

‌I. Physical Properties‌
Die-casting zinc alloys are characterized by ‌high fluidity, excellent surface finish, and dimensional stability‌, with the following key features:

‌High Density and Strength‌

· Density: ‌6.6–7.2 g/cm³‌ (higher than aluminum alloys but lower than steel), suitable for small high-strength components.

· Tensile strength: ‌250–440 MPa‌ (some grades can exceed 500 MPa after heat treatment).

· Elongation: ‌5–30%‌ (better ductility than most die-casting aluminum alloys).

‌Superior Fluidity and Thin-Wall Casting‌

· Low melting point (‌380–425°C‌), excellent flowability, capable of forming ultra-thin walls (‌0.2–0.5 mm‌) in complex geometries.

‌Surface Quality and Decorative Potential‌

· High as-cast surface finish, suitable for direct electroplating, painting, or imitation gold finishes (e.g., bathroom fixtures, jewelry).

‌Wear Resistance and Dimensional Stability‌

· Hardness: ‌80–120 HB‌ (higher than aluminum alloys), good wear resistance, and minimal long-term deformation.

‌Corrosion Resistance‌

· Requires surface treatments (e.g., electroplating, passivation) to prevent oxidation, especially in humid environments.

‌Thermal/Electrical Conductivity‌

· Thermal conductivity: ‌100–120 W/(m·K)‌ (moderate).

· Electrical conductivity: ‌25–30% IACS‌.

 

‌II. Main Die-Casting Zinc Alloy Grades‌

Key grades categorized by international standards and applications:

‌1. International Grades (ASTM/EN Standards)‌
· ‌Zamak 3‌ (Zn-Al-Cu alloy)

· ‌Features‌: Balanced properties, most widely used in appliances and hardware.

· Composition: Al 3.9–4.3%, Cu 0.03–0.06%.

· ‌Zamak 5‌ (Zn-Al-Cu alloy)

· ‌Features‌: High strength and wear resistance; ideal for automotive locks and gears.

· Composition: Al 3.9–4.3%, Cu 0.7–1.1%.

· ‌ZA-8‌ (Zn-Al alloy)

· ‌Features‌: High aluminum content (Al 8.4–8.8%), excellent high-temperature resistance; used in small engine components.

 

‌2. Eco-Friendly Lead-Free Alloys‌
· ‌Zamak 7‌

· ‌Features‌: Lead-free (Pb ≤0.002%), RoHS-compliant; used in electronic connectors and medical devices.

‌3. Specialty Grades‌
· ‌Zn-4Al-0.1Mg‌

· ‌Features‌: High creep resistance; suitable for pressure-bearing components (e.g., valves).

· ‌Zn-22Al‌ (Superplastic Alloy)

· ‌Features‌: Ultra-high elongation (>1000%); used for complex precision moldings.

 

‌III. Selection Guidelines‌

· ‌Automotive Parts‌: Prioritize ‌Zamak 5‌ or ‌ZA-8‌ (high strength and wear resistance).

· ‌Consumer Electronics/Aesthetic Parts‌: Use ‌Zamak 3‌ (low cost, easy electroplating).

· ‌Eco-Sensitive Applications‌: Mandatory use of ‌Zamak 7‌ (lead-free compliance).

· ‌High-Temperature Environments‌: Opt for ‌ZA-8‌ or magnesium-containing alloys (creep resistance).