Zinc Die Cast Lock Hardware | Padlocks & Deadbolts

Zinc die cast lock hardware is one of the oldest and largest applications of hot-chamber die casting. Padlock bodies, deadbolt housings, mortice lock cases, and cylinder housings combine dimensional precision for mechanism operation with the decorative surface quality required for chrome, nickel, and satin finish plating.

KastMfg produces lock hardware in Zamak 5 (standard for structural security applications) and Zamak 3 (decorative hardware and volume-driven programs), with multi-cavity tooling up to 8 cavities for production economics.

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Parts in This Family

Type	Alloy	Surface	Volume Range
Padlock body (all sizes)	Zamak 5	Chrome, Ni, powder	100K-M/year
Deadbolt housing	Zamak 5	Satin Ni, chrome	50K-M/year
Mortice lock case	Zamak 5	Chrome, brass plate	50K-M/year
Cylinder housing	Zamak 5	Ni, chrome	200K-M/year
Cam lock body	Zamak 5	Ni, chrome	100K-M/year
Furniture lock case	Zamak 3 or 5	Ni, antique brass	50K-M/year
Door handle mechanism	Zamak 5	Chrome, satin Ni	100K-M/year

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Why Zamak 5 for Security Hardware

Zamak 5's 1% copper addition over Zamak 3 raises tensile strength from 283 to 331 MPa (+17%) and compressive yield from 414 to 600 MPa (+45%). Lock bodies must resist forced-entry loading -Zamak 5's higher compressive yield provides meaningful resistance. Plating quality is identical to Zamak 3.

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Surface Quality for Plating

Decorative chrome plating requires the smoothest possible as-cast substrate. KastMfg achieves Ra 0.8-1.3 μm on visible faces -no vibratory polishing required before plating in most programs. This smooth base requires minimal pre-plating preparation, reducing customer's plating cost.

Critical: SHG zinc ingot only (99.99% purity). Lead content <=0.005%, Cadmium <=0.004%, Tin <=0.003%. Above these limits, zinc pest causes inter-granular corrosion visible as blistering under the chrome layer after plating. KastMfg verifies every melt by OES spectrometer. See zinc lock body case study.

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Die Life Economics

Zinc hot-chamber dies: 500,000-1,000,000+ shots. At 2.4 million pieces/year on a 3-cavity die, one die set runs 17 months before major maintenance. Tooling amortization: fractions of a cent per part. This is the economic foundation of high-volume decorative hardware.

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Minimum Wall Thickness

0.8-1.2 mm for security hardware profiles. 0.5 mm achievable for ornamental profiles with gate optimization. Below 0.4 mm requires design-specific feasibility review.

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Applications

Padlocks (combination, key, high-security) -> Door deadbolts and mortice locks -> Cabinet and furniture locks -> Container and shipping hardware -> Luggage security hardware -> Bicycle locks

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Lock hardware inquiry: casting@kastdiecast.com | +86 138 1403 4409 | No.6, Rungu Road, Nanjing, China

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