ZA-8 Zinc-Aluminum Alloy -Highest Strength Zinc Die Casting

ZA-8 contains approximately 8% aluminum -double the Zamak family's 4%. This elevated aluminum content produces the highest tensile strength (374 MPa) and hardness (100 HRB) of commonly die cast zinc alloys, with improved elevated-temperature performance and excellent bearing properties that Zamak grades cannot match.

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Chemical Composition

Element	Nominal %	Range
Aluminum (Al)	8.4	8.0-8.8
Copper (Cu)	1.0	0.8-1.3
Magnesium (Mg)	0.020	0.015-0.030
Iron (Fe)	-	0.075 max
Lead (Pb)	-	0.006 max
Cadmium (Cd)	-	0.006 max
Zinc (Zn)	Balance	-

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Mechanical Properties

Property	ZA-8	Zamak 5	Zamak 3
Tensile strength	374 MPa	331 MPa	283 MPa
Yield strength	290 MPa	228 MPa	200 MPa
Elongation	8%	7%	10%
Hardness	100 HRB	91 HRB	82 HRB
Compressive yield	641 MPa	600 MPa	414 MPa
Fatigue strength	67 MPa	56 MPa	48 MPa

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Physical Properties

Property	ZA-8
Density	6.30 g/cm³ (slightly lower than Zamak -more aluminum)
Melting range	375-404°C
Casting temperature	420-450°C
Thermal conductivity	115 W/m·K
Max service temperature	~110°C (vs Zamak's ~100°C)

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Hot Chamber vs Cold Chamber for ZA-8

ZA-8 is castable in hot-chamber machines but operates at the upper temperature limit of hot-chamber capability. The higher aluminum content raises casting temperature to 420-450°C, increasing thermal stress on the submerged injection system. KastMfg casts ZA-8 in hot chamber with steel selection appropriate to the higher operating temperature. For larger parts or lower volumes, cold-chamber casting is an alternative.

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ZA-8 Bearing Properties

ZA-8's hardness (100 HRB) and compressive yield strength (641 MPa) make it suitable for self-lubricating bearing applications -replacing bronze or nylon in moderate-speed, moderate-load service:

• Conveyor idler and drive roller end bearings
• Industrial equipment pivot bearings
• Automotive interior mechanism pivot points
• Door hinge and mechanism bearings in furniture

The zinc matrix with distributed aluminum-copper phases provides adequate boundary lubrication performance where greased maintenance is infrequent.

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Applications

• High-load mechanical components where Zamak 5 is marginal
• Bearing and bushing applications replacing bronze in moderate service
• Gear and ratchet components
• Industrial coupling and clutch components
• Higher-temperature enclosures (up to 110°C service)
• Die casting tooling components (wear-resistant inserts and guides)

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ZA-8 vs Zamak 5 -When to Upgrade

Choose ZA-8	Choose Zamak 5
Load-bearing wear surfaces required	Standard load-bearing hardware
Service temperature up to 110°C	Service below 100°C
Bearing application (self-lubricating)	Non-bearing function
Maximum strength required	Strength adequate

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ZA-8 inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China

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ZA-8 Casting Process Considerations

ZA-8 can be cast in hot-chamber machines but operates at the upper limit of hot-chamber capability. The higher aluminum content (8.4% vs Zamak's 4%) raises the casting temperature to 420-450°C -approximately 25-30°C higher than Zamak 3/5. At this elevated temperature, the steel gooseneck in hot-chamber machines experiences faster wear than in Zamak production.

KastMfg casts ZA-8 in dedicated hot-chamber machines with gooseneck steel selection appropriate for the elevated operating temperature. For larger parts or programs where hot-chamber economics do not apply, ZA-8 can also be cast in cold-chamber machines -losing the fast-cycle advantage but gaining access to larger machine tonnage.

Cycle time for ZA-8 is slightly longer than Zamak (20-30 seconds vs 15-20 seconds) due to the higher casting temperature requiring slightly longer solidification time.

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ZA-8 vs ZA-12 -Why ZA-8 Is More Widely Used

ZA-12 (12% aluminum) offers even higher tensile strength (404 MPa) and hardness, but cannot be processed in hot-chamber machines -its aluminum content causes unacceptable gooseneck attack. ZA-12 requires cold-chamber processing, eliminating the fast-cycle economics that make zinc alloys attractive for high-volume production.

ZA-8 occupies the optimal position: strong enough for bearing and high-load applications, yet processable in hot-chamber machines for production economics.

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Surface Finishing for ZA-8

ZA-8 accepts the same surface treatments as Zamak alloys:

Finish	ZA-8 Suitability	Notes
Chrome plating	Good	Higher aluminum may affect plating bath parameters slightly vs Zamak
Nickel plating	Good	Standard pre-treatment required
Powder coating	Excellent	Same process as Zamak
Anodizing	Not recommended	High zinc content -anodizing not suitable for ZnAl alloys
Clear lacquer	Good	Preserves metallic appearance

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Equivalent Designations

Standard	Designation
ASTM B86 (USA)	ZA-8
EN 1774 (Europe)	ZnAl8Cu1
ILZRO 12	ZnAl8 (earlier designation)

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ZA-8 inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China