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Zinc CNC Machining Services from Trusted China Suppliers and Factory for Precision Parts
Zinc alloys typically refer to alloys with zinc as the base, primarily alloyed with elements such as aluminum, copper, and magnesium. Their most prominent feature is excellent castability, making them suitable for manufacturing parts with complex shapes.
Simultaneously, their superior machinability allows subsequent CNC precision machining to easily achieve high dimensional accuracy and excellent surface finish.
Furthermore, zinc alloys offer good wear resistance, damping capacity, and comprehensive electromagnetic shielding (EMI/RFI) capability, making them an engineering material that combines functionality with economy.
- 🏗️Excellent Castability — Ideal for complex-shaped parts via die casting
- ⚙️CNC Machinability — Achieves high dimensional accuracy & surface finish
- 🛡️Wear Resistance — Suitable for functional and structural components
- 📡EMI/RFI Shielding — Comprehensive electromagnetic shielding capability
Common Zinc Alloy Grades and Characteristics
1 Zamak 3 (Zinc Alloy No. 3)
Characteristics: The most versatile and commonly used die-casting zinc alloy. It possesses the best fluidity and dimensional stability, along with good mechanical properties and surface treatment performance. Its low copper content means its creep resistance and strength are slightly lower than Zamak 5, but it offers better ductility.
Typical Applications: Complex thin-walled parts without extremely high strength requirements, such as toy models, zipper pulls, small gears, decorative items, and numerous consumer electronics housings.
Zamak 3 Typical Properties (As Die-Cast)
| Property | Value | Notes |
| Tensile Strength (MPa) | 280 – 320 | Good overall strength |
| Yield Strength (MPa) | — | |
| Elongation at Break (%) | 10 – 20 | Exhibits good ductility |
| Hardness (Brinell) | ~ 82 | |
| Density (g/cm³) | 6.6 | Significantly higher than aluminum and plastics |
| Note: Values are typical ranges, specific to casting process and condition. | ||
2 Zamak 5 (Zinc Alloy No. 5)
Characteristics: Based on Zamak 3 with the addition of about 1% copper, thereby increasing tensile strength, hardness, and creep resistance, but slightly reducing impact toughness and ductility. It is the most widely used high-strength die-casting zinc alloy.
Typical Applications: Functional and structural parts requiring higher strength and wear resistance, such as automotive door locks, fuel system components, tool housings, premium hardware, and business machine parts.
Zamak 5 Typical Properties (As Die-Cast)
| Property | Value | Notes |
| Tensile Strength (MPa) | 330 – 380 | Strength higher than Zamak 3 |
| Yield Strength (MPa) | — | |
| Elongation at Break (%) | 7 – 15 | |
| Hardness (Brinell) | ~ 91 | Higher hardness, more wear-resistant |
| Density (g/cm³) | 6.7 | Similar to Zamak 3 |
| Note: Values are typical ranges, specific to casting process and condition. | ||
3 ZA-8 (Zinc-Aluminum Alloy No. 8)
Characteristics: A zinc-aluminum alloy containing about 8.4% aluminum, typically produced by gravity casting. It has the best castability among all ZA series alloys and offers excellent bearing properties and wear resistance. Compared to the Zamak series, it retains better strength and dimensional stability at elevated temperatures.
Typical Applications: Bearings, bushings, sliders, wear-resistant components, and engineering structural parts that need to operate in moderately elevated temperature environments.
4 Kirksite (Mold Zinc Alloy)
Characteristics: A zinc-based alloy specifically designed for manufacturing prototype molds, low-melting-point injection molds, and fixtures. It has a low melting point, is easy to machine, and can quickly and cost-effectively replicate complex mold cavities for small-batch plastic part trial production or sheet metal forming.
Typical Applications: Prototype injection molds, blow molds, sheet metal stamping/form dies, checking fixtures, and jigs.
Frequently Asked Questions
Q What is the difference between Zamak 3 and Zamak 5 zinc alloys?
Zamak 3 is the most widely used die-casting zinc alloy, offering excellent fluidity, dimensional stability, and good ductility. Zamak 5 adds approximately 1% copper to the Zamak 3 base, which increases tensile strength (330–380 MPa vs. 280–320 MPa), hardness (~91 HB vs. ~82 HB), and creep resistance, but slightly reduces ductility and impact toughness. Choose Zamak 5 when higher mechanical performance is required.
Q What are the main advantages of zinc alloys over aluminum alloys for die casting?
Zinc alloys have a lower melting point than aluminum, which reduces energy consumption and extends die life. They also offer superior castability for thinner walls and more intricate geometries, faster cycle times, and excellent surface finish straight from the die. However, zinc alloys are denser than aluminum, making them less suitable when weight is a critical concern.
Q Can zinc alloy die-cast parts be used for electromagnetic shielding (EMI/RFI)?
Yes. Zinc alloys provide comprehensive electromagnetic shielding (EMI/RFI) due to their metallic conductivity. They are commonly used in housings for electronic devices, connectors, and enclosures where shielding sensitive components from electromagnetic interference is required.
Q What is Kirksite and when should it be used instead of steel tooling?
Kirksite is a zinc-based mold alloy designed for low-volume tooling applications such as prototype injection molds, blow molds, and sheet metal forming dies. It is chosen over steel tooling when rapid turnaround and low cost are priorities — typically for small-batch production, design validation, or trial runs — since it is easy to machine and cast at low temperatures, but is not suited for high-volume production due to lower hardness and durability.
Q What surface treatments are compatible with zinc alloy die-cast parts?
Zinc alloy parts are highly compatible with a wide range of surface treatments, including electroplating (chrome, nickel, copper), powder coating, painting, anodizing (for ZA series), and chemical conversion coatings. Zamak 3 in particular is noted for excellent surface treatment performance, making it ideal for decorative applications requiring a high-quality finish.
Q Is ZA-8 suitable for high-temperature applications compared to Zamak alloys?
ZA-8 offers better strength retention and dimensional stability at moderately elevated temperatures compared to the Zamak series (Zamak 3 and Zamak 5). Its higher aluminum content (~8.4%) contributes to improved performance under thermal stress, making it a preferred choice for bearings, bushings, and structural components that operate in warmer environments. However, it is still not recommended for high-temperature industrial applications where aluminum or steel alloys would be more appropriate.
Finishes and Post-Processing Options
The zinc alloy substrate is highly suitable for various surface treatments to enhance decoration, protection, or functionality:
Electroplating: Such as chrome, nickel, gold, or silver plating, providing a highly decorative appearance, excellent wear and corrosion resistance. This is the most common choice.
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Passivation or Chromate Conversion Coating:
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Powder Coating:
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Painting:
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Physical Vapor Deposition (PVD):
Design and Machining Considerations
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Process Selection:
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Design Considerations:
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Material Selection:
Zamak 3 and 5 are suitable for the vast majority of general-purpose parts requiring good appearance and strength; ZA-8 is better for wear and bearing applications; for making rapid tooling, choose specialized alloys like Kirksite.
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