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Zinc CNC Machining Services from China Suppliers - Precision Parts by Trusted Factory
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.
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Common Zinc Alloy Grades and Characteristics
Grade 01
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. | ||
Grade 02
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. | ||
Grade 03
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.
Grade 04
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.
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Frequently Asked Questions (FAQ)
Q1
What is the difference between Zamak 3 and Zamak 5?
Zamak 3 is the most commonly used general-purpose die-casting zinc alloy, offering excellent fluidity, dimensional stability, and ductility. Zamak 5 contains approximately 1% additional copper, which increases its tensile strength, hardness, and creep resistance, making it better suited for structural and functional parts that require higher mechanical performance. The trade-off is slightly reduced ductility and impact toughness compared to Zamak 3.
Q2
What makes zinc alloys suitable for die casting?
Zinc alloys have a relatively low melting point and excellent fluidity, which allows them to fill complex mold cavities with high precision. This results in near-net-shape parts with tight tolerances, fine surface detail, and thin walls — all with minimal post-processing required. Their castability is considered superior to many other metals used in die casting.
Q3
Can zinc alloy parts be used for CNC machining after casting?
Yes. Zinc alloys have excellent machinability, making them highly compatible with CNC precision machining operations. After die casting, parts can be further machined to achieve tighter dimensional tolerances, smoother surface finishes, or more complex geometries that cannot be produced directly through casting alone.
Q4
What is ZA-8 and when should it be chosen over Zamak alloys?
ZA-8 is a zinc-aluminum alloy with approximately 8.4% aluminum content. It is produced by gravity casting rather than pressure die casting and offers superior bearing properties, wear resistance, and better performance at elevated temperatures compared to the Zamak series. It is the preferred choice for applications such as bearings, bushings, and structural components that must function reliably in moderately high-temperature environments.
Q5
What is Kirksite used for, and why is it different from standard zinc alloys?
Kirksite is a specialized zinc-based alloy formulated specifically for tooling applications rather than end-use parts. Its low melting point and excellent machinability make it ideal for quickly producing prototype injection molds, blow molds, stamping dies, and fixtures. It enables manufacturers to produce small-batch plastic or sheet metal trial parts cost-effectively and rapidly, without committing to expensive hardened steel tooling.
Q6
Do zinc alloys provide electromagnetic shielding properties?
Yes. Zinc alloys offer good comprehensive electromagnetic shielding (EMI/RFI) capability. This makes them a practical choice for electronic device housings and enclosures where protection against electromagnetic interference is required, combining shielding performance with the structural and aesthetic benefits of metal die casting.
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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