Zamak 7 is a high-purity zinc alloy recognized for its exceptional flowability, corrosion resistance, and refined surface finish. With ultra-low copper content, it significantly reduces defects and enhances plating results. Thanks to its excellent ductility and dimensional stability, Zamak 7 is ideal for producing thin-walled, complex parts that demand both strength and an appealing appearance. Among the Zamak family, Zamak 7 delivers a superior balance of castability, form, and long-term durability, making it a popular choice in zinc die casting projects.
This article outlines Zamak 7’s chemical makeup, physical and mechanical characteristics, standout features, surface treatment options, and its comparison with other Zamak alloys. If you’re seeking a premium solution for precision zinc die casting components, Zamak 7 might be your best option.
Main Elemental Composition
Zinc (Zn)
Comprising 95.6% – 96.2% of the alloy, zinc serves as the base metal, providing structural strength and overall alloy stability.
Aluminum (Al)
Aluminum, present at 3.8% – 4.3%, enhances casting performance by improving material strength and melt flow, allowing for better casting outcomes.
Magnesium (Mg)
Magnesium, present at 0.02%–0.06 %, refines the grain structure, boosts corrosion resistance, and ensures uniform casting quality.
Copper (Cu)
With a maximum of 0.003%, copper is kept at much lower levels than in other Zamak alloys. This reduces corrosion risk, improves plating adhesion, and extends the service life.
Impurities (Fe, Cd, Sn, Pb, etc.)
The total impurity content is maintained at ≤ 0.012%, which helps avoid casting defects like porosity and shrinkage, ensuring consistent product quality.
Mechanical and Physical Properties
Mechanical Property
Zamak 7 comes with excellent mechanical properties.
Its tensile strength and yield strength meet the load-bearing requirements of structural parts, with high elongation, not easy to break, and strong processing adaptability.
Its hardness also supports its long-term use under moderate mechanical stress.
The following values are typical ranges for Zamak 7 in the as-cast condition:
-
Tensile Strength: 280–285 MPa
-
Yield Strength: 220–228 MPa
-
Elongation: 10% – 13%
-
Hardness: 80–82 HB
Physical Property
Zamak 7 has excellent physical stability, moderate density, and a narrow melting point range, making it suitable for precision zinc die casting.
Its high thermal conductivity and stable thermal expansion coefficient make it suitable for parts that require dimensional accuracy and heat dissipation.
-
Density: 6.6 – 6.7 g/cm³
-
Melting Range: 380 – 390°C
-
Thermal Conductivity: 110 – 115 W/m·K
-
Electrical Conductivity: 25% – 27% IACS
-
Thermal Expansion: 26 – 28 µm/m·°C
Core Characteristics of Zamak 7
Outstanding Flowability
Zamak 7 is the most fluid alloy in the Zamak family. Its high aluminum content and refined melt structure give it very low viscosity when molten.
It can fill complex mold cavities with precision, making it ideal for complex shapes and very thin-walled parts, with almost no post-processing required.
Superior Surface Quality
Because of its purity and low copper level, Zamak 7 castings exhibit smooth, clean surfaces right out of the mold.
This makes them highly compatible with decorative finishes such as chrome plating, powder coating, or custom painting.
Excellent Dimensional Precision
Zamak 7’s low thermal expansion rate makes it extremely dimensionally stable during the casting process.
Even during rapid cooling, its shrinkage and deformation are minimal, and the castings are highly accurate and can meet strict tolerance requirements.
Exceptional Ductility
Among all Zamak alloys, Zamak 7 has the highest ductility. Its high purity and low copper content help prevent brittle behavior and intergranular corrosion.
The small amount of magnesium also refines the grain and enhances flexibility. It maintains stability even under load or mechanical stress.
Enhanced Corrosion Resistance
With copper content kept to a minimum, Zamak 7 performs exceptionally well in corrosive and humid environments.
It surpasses other Zamak alloys in salt spray and humidity tests, maintaining a flawless surface over time without signs of pitting or peeling.
Post-Casting Processes
Surface Treatment
Zamak 7 is suitable for a variety of surface treatment processes. Common ones include electroplating chrome, electroplating nickel, powder coating, and spray painting.
Due to its good surface finish, the electroplating layer adheres evenly and has few defects, which is suitable for high-end finishes such as bright chrome and satin nickel.
Post-Machining
Zamak 7 offers excellent machinability. It causes minimal wear on cutting tools and supports precise drilling, milling, threading, and tapping operations.
Thanks to its ductility, Zamak 7 also handles press-fitting, riveting, and other mechanical assembly processes without cracking or damage.
Compatibility of Zamak 7 with the Die Casting Process
Zamak 7 is very suitable for hot chamber die casting, which is the main process for zinc-based alloys.
It has strong fluidity and good mold filling performance, which can significantly reduce defects such as pores, cold shuts, and shrinkage.
In high-speed automated die-casting production lines, Zamak 7 has high melt stability and consistent flow behavior, which helps to extend mold life, reduce equipment downtime, and adapt to large-scale, low-cost production needs.
Whether it is small precision parts or medium-volume orders, Zamak 7 can provide stable quality and high production efficiency, making it a top material choice for zinc die casting companies worldwide.
Typical Application Fields
Automobile
Zamak 7 is widely used in automotive interior parts such as trims, buttons, knobs, etc., and is also used in structural parts such as gear housings and brackets.
Zamak 7 has excellent adaptability in both types of automotive applications, taking into account both appearance and performance.
Consumer Electronics
Applied to parts such as housings, frames, plug connectors, etc. that require high dimensional accuracy and appearance processing.
Its excellent finish and electroplating compatibility are suitable for creating the appearance of high-end consumer electronic products.
Furniture Hardware
Used to make high-end handles, knobs, hinges, decorative parts and other parts with metallic texture.
Zamak 7 has a flat surface, is easy to polish and electroplate, and can improve the overall texture and service life of furniture.
Telecom
Zamak 7 is commonly found in antenna housings, signal connectors, terminal assemblies, and other parts that have high requirements for conductivity and corrosion resistance, and is suitable for outdoor and high-frequency communication equipment.
Zamak 7 vs. other Zamak Alloys
Compared to Zamak 3
Zamak 7 retains Zamak 3’s excellent casting characteristics but adds better ductility, smoother surfaces, and enhanced corrosion resistance.
It’s more suitable for applications that demand high-end surface finishes.
Compared to Zamak 5
Zamak 5 offers slightly higher strength due to more copper, but sacrifices corrosion resistance and surface smoothness.
Zamak 7 is a better option when finish quality and durability are critical.
Compared to Zamak 2
Zamak 2 provides the highest strength and hardness among Zamak alloys, but has low ductility and higher brittleness.
It also has reduced corrosion resistance due to high copper levels.
Zamak 7 is more balanced for applications requiring flexibility and environmental stability.
When to Choose Zamak 7
Zamak 7 is the right choice for:
-
High-end parts that need decorative plating.
-
Components with thin walls or complex geometries.
-
Parts exposed to moisture or corrosive environments.
-
Parts requiring flexibility, dimensional accuracy, and impact resistance.
Zamak 7 may not be ideal for:
-
Projects needing maximum strength or hardness (Zamak 2 or Zamak 5 are better fits).
-
Budget-limited applications where Zamak 3 offers better cost efficiency.
Conclusion
Zamak 7 stands out in the zinc die casting industry for its purity, smooth finish, and corrosion resistance.
It combines excellent flow, high ductility, and strong dimensional control, making it an outstanding choice for precision zinc die casting components that demand both function and appearance.
As a trusted zinc die casting company and aluminum alloy die casting manufacturer in China, CEX Casting offers full-service solutions from mold design through to product shipment.
Contact us today to see how Zamak 7 can benefit your next die casting project.