Zinc Die Casting -Precision, Surface Quality, and Thin-Wall Capability

Zinc die casting at KastMfg uses hot-chamber high-pressure machines to produce complex, tight-tolerance components in Zamak 3, Zamak 5, ZA-8, and other zinc alloys. Zinc's low melting point (385-390°C) enables fast cycle times of 15-25 seconds, extended die life of 300,000 to over 1,000,000 shots, and the thinnest achievable walls of any die casting metal -reliably to 0.4 mm.

The result is a process well suited to high-volume, dimensionally precise, cosmetically demanding components where the smooth as-cast surface, fine detail reproduction, and decorative finishing capability of zinc are decisive advantages.

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Zinc Alloys Available

Alloy	Key Composition	Tensile (MPa)	Yield (MPa)	Elongation	Best Use
Zamak 3 (Alloy 3)	Zn-4% Al-0.04% Mg	283	200	10%	Most widely used -balanced properties, excellent castability
Zamak 5 (Alloy 5)	Zn-4% Al-1% Cu	331	228	7%	Higher strength and hardness -preferred where load-bearing
Zamak 2 (Alloy 2)	Zn-4% Al-3% Cu	359	283	7%	Maximum strength Zamak alloy -tool-like applications
ZA-8	Zn-8% Al-1% Cu	374	290	8%	Highest zinc alloy strength -gravity or hot-chamber casting
ZA-12	Zn-12% Al	404	-	4%	Bearing applications, high hardness

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Technical Capabilities

Parameter	KastMfg Specification
Casting process	Hot-chamber HPDC
Machine tonnage	80T -400T
Minimum wall thickness	0.4 mm (standard), 0.3 mm achievable with optimization
Dimensional tolerance	CT3-CT5 (ISO 8062) -tighter than aluminum
Surface finish (as-cast)	Ra 0.8-1.6 μm -smoother than aluminum
Weight range	0.005 kg -5 kg
Die life	300,000 -1,000,000+ shots
Typical cycle time	15-25 seconds
Shot monitoring	Injection velocity, pressure, and temperature logged every shot

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Why Zinc Die Casting?

Thinnest achievable walls. At 0.4 mm minimum wall thickness, zinc die casting produces thinner walls than any other die casting metal. This enables miniaturization, complex internal geometry, and ultra-lightweight small components that aluminum cannot form.

Best surface finish as-cast. Zinc's low viscosity and fast-filling characteristic produce as-cast surfaces of Ra 0.8-1.6 μm -smoother than aluminum (1.6-2.2 μm). This smooth base minimizes pre-plating preparation, making zinc the preferred substrate for decorative chrome, nickel, and gold electroplating.

Tightest dimensional accuracy. CT3-CT5 tolerances as-cast (compared to CT4-CT6 for aluminum) mean zinc parts often require no post-cast machining for dimensional features. This reduces secondary operation cost and simplifies the supply chain.

Longest die life. Zinc's low casting temperature (385-390°C vs 650°C for aluminum) is far less thermally aggressive on the H13 die steel. Properly maintained zinc dies routinely exceed 500,000 shots; exceptional cases exceed 1,000,000. This dramatically reduces the tooling cost per unit over a program lifetime.

Fast cycle times. Shorter solidification time means 15-25 second cycles -faster than equivalent aluminum parts. At high volume, this directly reduces unit cost.

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Surface Finishing for Zinc

Zinc die castings accept a wide range of decorative and functional finishes:

Finish	Application
Chrome plating (decorative)	Automotive trim, door handles, hardware fittings -zinc is the preferred substrate
Nickel plating	Electronics, plumbing fittings, industrial hardware
Gold plating	Jewelry fittings, decorative hardware, luxury consumer goods
Powder coating	Industrial and outdoor components requiring color and corrosion protection
Painting	Consumer products where color matching is required
Clear lacquer	Preserves the as-cast metallic appearance

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Industries and Applications

Automotive Door handles, lock cylinders, fuel cap covers, interior trim components, seat hardware, mirror housings. Zamak 5 for load-bearing; Zamak 3 for decorative parts requiring direct plating.

Hardware and Building Products Padlocks, door handles, deadbolts, cabinet hardware, window fittings, bathroom accessories. High volume, consistent quality, direct chrome or nickel plating.

Electronics and Connectors Connector housings, terminal blocks, shield cans, EMI shielding brackets, switch housings. Zamak 3's excellent electrical conductivity and castability make it standard for these applications.

Consumer Products Zip fasteners, belt buckles, eyewear frames, toys, sporting goods fittings. Zinc's fine surface detail and plating suitability are ideal for visible consumer-facing components.

Industrial Precision Small gears, bearing retainers, precision brackets, bushings, pump impellers. ZA-8 or Zamak 2 for load-bearing applications.

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Zinc vs Aluminum -Quick Decision Guide

Choose zinc when:

• Walls are thinner than 1.2 mm
• Part requires direct electroplating (chrome, nickel)
• Maximum dimensional precision on small parts
• Very high volume where long die life reduces total cost
• Part weight and size are small-to-medium

Choose aluminum when:

• Weight is a primary concern (zinc is 2.4x heavier than aluminum)
• Operating temperature exceeds 100°C
• Thermal conductivity is important (heat sinks, motor housings)
• Part size exceeds 5 kg

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Frequently Asked Questions

Is zinc die casting stronger than aluminum?

Zamak 5 tensile strength (331 MPa) exceeds A380 aluminum (317 MPa) in absolute terms. However, aluminum's strength-to-weight ratio is significantly better -aluminum is 2.4x lighter for equivalent volume. Choose based on your application's primary requirement: if weight matters, choose aluminum; if surface finish, thin walls, or plating suitability matter, choose zinc.

Why does zinc have better die life than aluminum?

Zinc's casting temperature (385-390°C) is approximately 250-300°C lower than aluminum (620-700°C). The H13 tool steel die experiences less thermal fatigue per cycle, resulting in dramatically longer service life. A zinc die that produces 500,000+ parts would need replacement or major repair after 80,000-120,000 shots running aluminum.

Can zinc die castings be used outdoors?

Bare zinc alloys have moderate corrosion resistance -adequate for indoor applications but requiring protection for outdoor or humid environments. Chrome-plated zinc castings perform well outdoors (the chrome and nickel intermediate layers provide corrosion protection). Powder-coated zinc is also suitable for outdoor use.

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Zinc die casting inquiry: yaoqingpu1983@gmail.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China