ZA-27 is a zinc-aluminum alloy containing approximately 27% aluminum, renowned for its exceptional strength, rigidity, and wear resistance. It is the strongest and lightest alloy in the ZA series and is widely used in structural components in the automotive, industrial, and mechanical sectors. Its excellent machinability and thermal properties make ZA-27 ideal for medium- to large-sized parts produced by gravity casting or permanent mold casting.
This article will discuss ZA-27’s chemical composition, mechanical properties, physical characteristics, casting characteristics and considerations, machining and surface treatment, advantages and disadvantages, typical applications, and CEX Casting‘s ZA-27 solutions. Read on to learn how this material performs in real-world castings.
ZA-27 Chemical Composition
ZA-27 consists of zinc, aluminum, copper, and magnesium in precise proportions.
|
Element |
Typical Content (%) | Function Description |
|
Zinc (Zn) |
Balance (~70%) | Base metal providing structural support |
| Aluminum (Al) | 25–28% |
Increases strength and hardness |
|
Copper (Cu) |
2.0–2.5% |
Improves fatigue strength and bearing load capacity |
| Magnesium (Mg) | 0.01–0.05% |
Enhances castability and surface finish |
Mechanical Properties of ZA-27
ZA-27 is the alloy with the strongest mechanical properties in the ZA series.
|
Property |
Typical Value | Remarks |
| Tensile Strength | 380–400 MPa (55–58 ksi) |
Highest in the ZA series |
|
Yield Strength |
340–360 MPa (49–52 ksi) | Suitable for load-bearing structures |
| Elongation | ~1–2% |
Very low – brittle behavior |
|
Hardness |
Rockwell H80–H85 | Excellent wear resistance |
| Elastic Modulus | ~96 GPa |
High stiffness, low flexibility |
| Fatigue Strength | High |
Ideal for cyclic or vibration environments |
Physical and Thermal Properties of ZA-27
This alloy offers lightweight, high thermal conductivity, and strong dimensional stability.
|
Property |
Value | Remarks |
|
Density |
~5.0 g/cm³ (0.125 lb/in³) | Lighter than bronze and cast iron |
| Melting Range | 488–510°C (900–950°F) |
Low melting point helps energy-efficient casting |
|
Thermal Conductivity |
~110–113 W/m·K | Excellent for heat dissipation |
| Thermal Expansion | ~25 µm/m·K |
Predictable dimensional changes with heat |
|
Electrical Conductivity |
~27% IACS |
Moderate; not suitable for primary electrical parts |
ZA-27 Ingots
Casting Characteristics and Considerations
Suitable Casting Methods
ZA-27 is suitable for gravity casting and permanent mold casting. It is recommended for parts with simple structures and wall thicknesses ≥3mm.
Due to its poor flowability, the filling path should be short, and the mold layout should avoid long channels and complex corners.
This alloy is not recommended for the high-pressure die casting process or slender, thin-walled structures.
ZA-27 Gravity Casting
Shrinkage and Deformation Risks
This alloy has high solidification shrinkage. Localized hot spots are prone to shrinkage and collapse if not effectively fed.
It is recommended to conduct a thermal analysis before designing the mold to ensure that all thick-walled areas have connected shrinkage-feeding paths.
Isolated, closed areas should be avoided, and process risers should be added as necessary.
Mold Design Requirements
The mold should prioritize smooth metal flow and venting. Runners should be straight and well-spaced, with smooth transitions between the gate and the main runner.
Venting slots or vacuum assist should be installed at the ends or high points where gas cannot escape.
Chills and insulation blocks are only used to control the cooling rate and do not provide shrinkage-feeding functions.
Gating and Runner Strategies
Use multi-point gating and downstream runner design to shorten the filling distance and reduce pressure loss.
All gate cross-sections should be sufficiently large to accommodate the alloy’s low fluidity.
The pouring temperature should be between 510–530°C. Higher temperatures will exacerbate shrinkage, while lower temperatures will easily cause cold shuts.
Process Stability Requirements
Process parameters, especially casting die and metal temperatures, must be stably controlled.
It is recommended to use automated dosing equipment in conjunction with a mold-area temperature control system.
Cooling channels should be cleaned regularly to prevent blockage and uneven cooling.
Temperature and time data must be collected throughout the entire process to ensure batch consistency and traceability.
Machining and Surface Treatment
Machining Performance
ZA-27 offers smooth cutting performance, suitable for high-speed and precision machining, with minimal tool wear.
Carbide or high-speed steel tools are recommended. Short chips and the need for large amounts of coolant facilitate clean production.
Its high rigidity prevents deformation during machining, enabling tolerances of <±0.02mm to be achieved.
Surface Treatment Compatibility
ZA-27 is compatible with powder coating, electroplating, painting, and electroless nickel plating.
Sandblasting or alkaline cleaning is recommended before treatment to enhance adhesion.
Spray coating is suitable for exterior components, while electroplating is suitable for precision structures requiring corrosion protection.
Bare parts should not be used in humid or acidic environments and require surface protection.
Advantages of ZA-27
High Strength-to-Weight Ratio: With an aluminum content of 25–28%, it significantly improves strength while reducing weight. This is the strongest material in the ZA series, making it a suitable alternative to traditional materials such as copper alloys and cast iron.
Excellent Wear Resistance: Containing 2–2.5% copper, it forms a reinforcing intermetallic compound, increasing surface hardness; its low plasticity makes it less susceptible to deformation under sliding friction.
Good Dimensional Stability: Its high elastic modulus (approximately 96 GPa) and moderate thermal expansion coefficient maintain dimensional accuracy under heat and stress, and are less susceptible to fit issues caused by thermal expansion and contraction.
Excellent Machinability: The material exhibits uniform microstructure and is free of impurities, resulting in low cutting resistance and being suitable for high-speed precision machining, minimal tool wear, and manageable machining tolerances.
Limitations of ZA-27
Poor Flowability: The high aluminum content results in high melt viscosity and poor filling capacity, making it unsuitable for thin-walled or complex mold structures, and prone to cold shuts and short pours.
Extreme Solidification Shrinkage: The solidification interval is long, resulting in high shrinkage. Improper feeding can easily lead to defects such as shrinkage cavities and collapse, compromising part strength and density.
Poor Impact Resistance: With an elongation of only 1–2%, it is highly brittle and prone to fracture when subjected to impact or deformation, making it unsuitable for structural components that are exposed to these conditions.
Poor Corrosion Resistance: Zinc and aluminum are highly electrochemically active, susceptible to oxidation corrosion in humid, acidic, or salt spray environments, requiring protective coating or electroplating.
ZA-27 Industry Applications
Automotive Industry: Used in components such as steering housings, suspension brackets, and transmission supports. It combines high strength with lightweight construction, making it suitable for internal structural parts and dynamic components carrying medium loads.
ZA-27 Auto Part
Industrial Equipment: Widely used in parts subject to repeated movement or vibration, such as bushings, cams, and gear housings. It exhibits excellent fatigue strength and wear resistance, significantly extending component life.
Construction and Agricultural Machinery: Suitable for applications requiring high rigidity, such as structural brackets and pulleys. It maintains dimensional stability and resists deformation even under heavy loads.
Home Appliances and Tools: Commonly used in power tools and internal functional components of home appliances, such as mounting plates, arms, and subframes, meeting application requirements for good thermal conductivity and high structural precision.
CEX Casting’s ZA-27 Solution
Mold Flow Simulation
Mold flow analysis was conducted early in the project to simulate the molten metal filling path, cooling rate, and hotspot distribution, optimizing the gating and riser layout.
Simulations were used to predict defects, address ZA-27’s vulnerability to shrinkage and underfill, improve first-time yield, and reduce mold trial costs.
Centralized Melting System
A centralized melting furnace with online degassing and electromagnetic stirring ensures pure molten metal and uniform temperature.
The discharge temperature difference is controlled to ±5°C, and the composition fluctuation is controlled to ±0.2%, ensuring batch-to-batch consistency in mechanical properties and dimensional accuracy for ZA-27.
Centralized Melting System
Automated Production
Fully automated robotic pouring, mold temperature control, and cooling systems achieve closed-loop control, precisely controlling pouring temperature and solidification rhythm.
This effectively addresses the long solidification window and difficult-to-control shrinkage of ZA-27, ensuring consistency and microstructure density in large-scale production.
Rigorous Quality Inspection System
All ZA-27 products undergo process-level inspections, including X-ray inspection, tensile testing, helium seal testing, and metallographic analysis.
Key parameters and inspection data are archived to ensure structural integrity, reliable performance, and traceability of every product leaving the factory.
Conclusion
ZA-27 offers the highest strength and rigidity in the ZA series, while also being lightweight, high-strength, and excellent processability.
Despite its poor flowability and high shrinkage, it performs exceptionally well in gravity and permanent mold casting.
As a professional aluminum casting manufacturer, CEX Casting offers mold flow optimization, material purification, and automated production tailored specifically for ZA-27.
Looking to improve product performance? Contact us today to start your customized aluminum alloy casting solution.