ZA-27 Zinc Alloy - Highest-Strength Zinc Casting

ZA-27 (ZnAl27Cu2) is the strongest of the zinc casting alloys: 27% aluminum pushes tensile strength to around 421 MPa - into territory where it competes with some cast aluminum and bronze on strength while keeping zinc's excellent bearing behavior. It is a specialist alloy for engineers who have exhausted what ZA-12 can do.

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ZA-27 Chemical Composition

Element	Nominal %	Range
Aluminum (Al)	27.0	25.0 to 28.0
Copper (Cu)	2.0	2.0 to 2.5
Magnesium (Mg)	0.015	0.01 to 0.02
Iron (Fe)	-	0.075 max
Zinc (Zn)	Balance	-

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Mechanical Properties

Property	ZA-27	ZA-12	ZA-8
Tensile strength	421 MPa	400 MPa	374 MPa
Yield strength	379 MPa	317 MPa	290 MPa
Elongation	1 to 3%	4 to 7%	8%
Hardness	105 to 125 HB	95 to 115 HB	100 HB
Density	5.00 g/cm3	6.03 g/cm3	6.30 g/cm3
Max service temperature	~150°C	~120°C	~110°C

Two properties deserve attention: ZA-27 is the lightest zinc alloy (5.00 g/cm3 - 24% lighter than Zamak 3) and the most heat-tolerant (useful strength to roughly 150°C where Zamak grades are fading at 100°C).

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Casting ZA-27: What Makes It Difficult

ZA-27's wide freezing range (melting range roughly 376 to 484°C) creates real casting challenges:

• Shrinkage management. The long mushy zone demands generous risering (gravity) or intensification (cold-chamber) to avoid dispersed shrinkage porosity
• Gravity segregation. The density gap between aluminum-rich and zinc-rich phases means slow solidification can segregate the structure - process control matters
• No hot chamber. Like ZA-12, the high aluminum content rules out hot-chamber machines entirely

Cold-chamber die casting and tilt-pour gravity casting are the production routes. Sand casting works for prototypes and very large parts.

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Applications

• Heavy-duty bearings and bushings replacing bronze in mining, agricultural, and construction equipment
• Gears and worm wheels under high sustained load
• Structural brackets and levers where aluminum would need inserts
• Wear plates, guides, and slides in machinery
• Elevated-temperature hardware in the 100 to 150°C band

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ZA-27 vs ZA-12 vs Bronze

Consider ZA-27 when	Stay with ZA-12 when	Bronze still wins when
Loads exceed ZA-12's margin	ZA-12 meets the load case	Speeds and loads are extreme
Weight matters (lightest Zn alloy)	Castability and cost matter	Continuous high-speed rotation
Service above 120°C	Volume is high and parts small	Lubrication is impossible
Replacing machined bronze	-	-

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Frequently Asked Questions

Is ZA-27 a die casting alloy?

Only in cold-chamber machines. Its 27% aluminum content makes hot-chamber processing impossible, and its wide freezing range means it casts more like an aluminum alloy than a Zamak. Many ZA-27 parts are gravity cast.

Does ZA-27 corrode like other zinc alloys?

Similar atmospheric behavior to Zamak and ZA-8, but its higher aluminum content improves general corrosion resistance slightly. Outdoor or humid service still calls for coating or plating.

Can ZA-27 be heat treated?

ZA-27 castings are almost always used as-cast. Unlike A356 aluminum, there is no widely standardized T6-style strengthening treatment for ZA-27 in production; if your drawing calls out a stabilization cycle, we review it case by case at DFM.

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Related Zinc Resources

• zinc die casting - KastMfg zinc capability
• ZA-12 zinc alloy - the more castable high-strength grade
• ZA-8 zinc die casting - hot-chamber-compatible ZA
• zinc die casting alloys - full selection guide

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ZA-27 inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China