Product Category
ZNA — 7 Product Lines
Zinc Alloy
Die-Cast
Post-Machined
7 product lines of CNC precision post-machining on Zamak 3 and Zamak 5 zinc alloy die castings — bringing critical dimensions to ±0.05mm, holes to H8, threads to 100% go/no-go, and assembly mating faces to Ra ≤1.6μm. Die casting shapes; post-machining achieves precision.
Die-Cast Accuracy vs Post-Machined Accuracy
Feature
Die-Cast Only
Post-Machined
Bore / hole
±0.10–0.20mm
H8 ±0.02mm ◀
Hole position
±0.15–0.30mm
±0.05mm ◀
Mating face flat
±0.2–0.5mm
±0.05mm ◀
Thread quality
Variable
100% go/no-go ◀
±0.05mm
Post-machined
100%
Go/No-Go
7
Product Lines
±0.05mm
Post-Machined
H8
Bore Std
100%
Thread Inspect
24hr
Quote
Die-Cast Housing Post-Machine ✦
Electronics Housing Finish ✦
Mounting Hole Precision ✦
Thread Tapping ✦
Assembly Face Finish ✦
Small Structural Part ✦
Appliance Hardware Part ✦
Die-Cast Housing Post-Machine ✦
Electronics Housing Finish ✦
Mounting Hole Precision ✦
Thread Tapping ✦
Assembly Face Finish ✦
Small Structural Part ✦
Appliance Hardware Part ✦
Full Product Range
7 Zinc Alloy Post-Machined Parts Across
2 Application Categories
Zamak 3 · Zamak 5 · Bore H8 · Hole ±0.05mm · Thread 100% go/no-go · Chromate / Nickel Plated · MOQ 1 piece
Product Categories
Precision Machining OperationsQuote →
Five zinc alloy die-cast post-machining operations — housing bore and precision machining, mounting hole drilling and reaming, thread tapping, assembly mating face milling, and small structural part precision finishing. Zinc alloy (Zamak 3/5) machines at high cutting speed with excellent surface finish and minimal tool wear — the combination of die casting (for complex shape) and post-machining (for precision features) produces parts at lower total cost than machined-from-solid or precision casting alone.
ZNA-001/003/004
PRECISION / 001/003/004 — FEATURED
Housing Bore, Mounting Holes & Thread Tapping
Three core CNC post-machining operations on Zamak 3/5 zinc alloy die castings that together convert a near-net-shape casting into a precision assembly-ready part. (1) Housing bore H8 post-machining: bore as-cast ±0.10–0.20mm; CNC bored to H8 (±0.013–0.027mm) for shaft, bushing, or bearing seat fit. Concentricity ≤0.05mm. Bore Ra ≤1.6μm. (2) Mounting hole precision drilling and reaming: as-cast hole position ±0.15–0.30mm; CNC drilled and reamed to ±0.05mm position with H8 diameter tolerance for repeatable PCB, bracket, or chassis component alignment. Every hole 100% position-checked with pin gauge. (3) Thread tapping: M2–M12 CNC-tapped with calibrated spiral-point taps at controlled speed and torque. 100% go/no-go gauge inspection on every tapped hole — not sampled, not assumed from process control alone. Helicoil stainless inserts installed in specified threads requiring repeated assembly cycles (M4 and above with >20 assembly cycles). All three operations performed in single CNC setup where possible — minimising re-fixturing and maintaining feature-to-feature relationships.
Zamak 3 · Zamak 5Get Quote
ZNA-005
PRECISION / 005
Assembly Face Finishing
CNC-milled assembly mating faces on zinc die-cast parts. As-cast face flatness ±0.2–0.5mm — inadequate for tight-fit assembly. Post-milled to ±0.05mm flatness and Ra ≤1.6μm. All edges chamfered ≥0.3×45° or deburred by hand. Parting line trimmed flush. For housing mating interfaces, PCB mounting faces, and connector seating surfaces.
Zamak 3 · Zamak 5Get Quote
ZNA-006
PRECISION / 006
Small Structural Parts
Zamak 3/5 small structural die-cast parts with post-machined critical dimensions to ±0.05mm. Parting line trimmed flush; gate vestige removed; all burrs removed from machined features. Critical length/height dimensions machined to tolerance. CMM spot inspection on first article.
Zamak 3 · Zamak 5Get Quote
Materials: Zamak 3 (Z33520) · Zamak 5 (Z35531) · Zamak 2
Request All 5 →
Manufacturing Capability
What Zinc Die-Cast Post-Machining
Actually Corrects
🎯
Bore H8 from As-Cast ±0.20mm
As-cast zinc bores are ±0.10–0.20mm — adequate for clearance holes, not for bearing seats, shaft fits, or bushing housings. CNC boring to H8 (±0.013–0.027mm) in a single CNC operation. Zinc machines extremely cleanly at bore size — good dimensional control from a single boring pass. Concentricity ≤0.05mm bore-to-OD or bore-to-bore in multi-bore housings.
H8 ±0.02mmConc. ≤0.05mm
🔩
Thread 100% Go/No-Go — Every Hole
All tapped threads inspected with calibrated go/no-go gauges — 100% per hole, not sampled. Zinc is soft — die-cast threads (tapped in die casting) can have incomplete form due to die wear; CNC-tapped threads are consistently formed. Helicoil inserts installed where repeated assembly cycles are specified: M4+ with >20 cycles, all M2/M3 with high torque requirement.
100% go/no-goHelicoil option
🔲
Parting Line Trimming — Flush and Flat
Die-casting parting line flash is an unavoidable consequence of the process — material flows into the parting plane and solidifies as a thin fin. CNC milling of parting line surfaces produces a flat, flush surface within ±0.05mm — required for housing halves that must seal together, connector apertures that must be coplanar, and mating faces that must be flat for gasket sealing. Not deburring or grinding — precision milling to tolerance.
±0.05mm trimmedNot just deburred
Precision Specifications
Post-Machined Tolerances vs As-Cast Die-Cast Accuracy
📐
Post-Machined Tolerances
Bore (post-machined)
H8
Hole Position
±0.05 mm
Mating Face Flat
±0.05 mm
Surface (milled face)
Ra ≤1.6 μm
Thread (tapped)
6H (100% G/NG)
Aperture (milled)
±0.05 mm
⚙
Zamak Grade Reference
Zamak 3 UTS
283MPa
Most widely used. Best castability. Dimensional stability. Standard for electronics and general die casting.
Zamak 5 UTS
328MPa
Higher hardness and strength (1% Cu addition). Better thread strip resistance for M4+ structural threads.
Machinability
Near brass
High cutting speed, excellent surface finish, minimal tool wear. Economical post-machining vs steel.
EMI Shielding
Inherent
Electrical conductivity comparable to aluminium. Conductive chromate maintains EMI at housing interfaces.
Surface Treatments
Post-Machining Surface Treatment for Zinc Parts
Post-machined zinc surfaces expose bare zinc — a second treatment cycle or treatment-after-machining is essential to restore corrosion protection on machined areas.
🛡
Chromate (Clear / Yellow)
Standard for electronics housings — conductive, corrosion protection, zero dimensional change. Applied to entire part after all post-machining. Second chromate cycle covers freshly machined surfaces. Conductive chromate maintains EMI continuity at mating interfaces.
Electronics EMI
🔘
Electroless Nickel (3–8μm)
Hard, corrosion resistant, decorative. For home appliance hardware requiring silver metallic appearance. Better wear resistance than chromate. Uniform thickness — suitable for parts with complex post-machined geometry. Applied after all machining and deburring.
Appliance hardware
🎨
Powder Coat / Spray Paint
Over chromate base — for consumer product housings requiring specific colour and texture. Chromate provides adhesion base and corrosion barrier; paint adds appearance. Paint thickness (50–150μm) must be allowed for at DFM stage on precision mating faces.
Consumer products
✨
Electroplating (Ni/Cu/Cr)
Decorative bright nickel or copper-nickel-chrome stack for premium appearance hardware. Applied over copper strike on zinc substrate. Used for premium appliance fittings and decorative hardware requiring bright metallic appearance. Plating thickness specified — post-machine tolerance must allow for plating build-up.
Premium decorative
Our Advantage
Why Assemblers Choose Our Post-Machined Zinc Parts
G/N
100% Thread Go/No-Go — Not Sampled
Every tapped thread in every zinc part inspected with calibrated go/no-go gauges. Zinc is soft — a worn tap or incorrect speed produces out-of-tolerance threads that feel correct by hand but fail go/no-go. Assembly line thread failures are far more expensive than 100% inspection at the point of manufacture.
±0.05
Post-Machine ±0.05mm — Not ±0.20mm
Post-machining achieves ±0.05mm on critical features — not the ±0.10–0.20mm typical of as-cast zinc. We document the post-machined tolerances achieved, not the as-cast tolerance assumed. First article CMM report on all post-machined features available on request.
PL
Parting Line Milled — Not Just Deburred
Parting line trimming is CNC precision milling to ±0.05mm flatness — not manual deburring or grinding that produces inconsistent results. Consistent parting line finish ensures repeatable housing mating, consistent gasket compression, and repeatable connector aperture geometry across the entire production batch.
Cr
Re-Chromate After Machining
Post-machined zinc surfaces expose bare zinc that must be re-treated. We apply a second chromate cycle after all post-machining — covering both the original cast surfaces and the freshly machined surfaces in a single consistent treatment. Bare zinc on machined surfaces that are not re-treated will develop white rust within days.
Frequently Asked Questions
Zinc Alloy Post-Machining — Common Questions
Zamak 3 (Z33520, Zn-4Al-0.04Mg): most widely used, best castability, 283 MPa UTS, best dimensional stability. Standard for electronics and general die-cast housings. Zamak 5 (Z35531, Zn-4Al-1Cu-0.04Mg): 328 MPa, slightly harder, better thread strip resistance. Preferred for parts with structural threads and mounting hardware. Both machine extremely easily — near brass machinability.
As-cast accuracy: basic external dimensions ±0.10–0.20mm; parting line features ±0.15–0.30mm; bore/holes ±0.10–0.20mm; threads cast-in: variable quality. Post-machining achieves: bore H8 (±0.013–0.027mm); hole position ±0.05mm; mating face ±0.05mm flatness; threads 100% go/no-go. Post-machining is the economical method — die casting forms the complex shape; post-machining corrects the precision features only.
Yes — zinc taps cleanly. Practical range: M2 minimum (M1.6 possible but higher breakage rate); M2–M8 most economical; M12 maximum for standard boss dimensions. For repeated assembly: Helicoil inserts for M4+ with >20 cycles; strongly recommended for M2/M3 with high torque. 100% go/no-go on every hole — not sampled. Zinc thread strips progressively without inserts if over-torqued in assembly.
Post-machined zinc must be re-treated — bare machined surfaces expose unprotected zinc that oxidises rapidly. Chromate: conductive, standard for electronics housings. Electroless nickel (3–8μm): hard, decorative, appliance hardware. Powder coat over chromate: consumer product colour. Ni/Cu/Cr electroplate: premium decorative. We apply a second chromate cycle after all post-machining — covering both cast and machined surfaces.
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Send Your Drawing.
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Every enquiry includes a DFM review — tolerance feasibility, material confirmation, and process approach confirmed before production starts. MOQ 1 piece.
24hr
Quote Response
MOQ 1
Prototypes OK
ISO
9001:2015
📐
DFM Review on Every Enquiry
Tolerance feasibility, fixturing strategy, and material confirmation. Specific, actionable feedback — not generic pushback.
🎯
First Article Inspection — Standard
FAI report on every new run. Material certs and surface treatment certs included with every shipment.
🔄
Same Process: Prototype to Production
Process plan from your prototype applies to production batches. No re-qualification when you scale.
⚙
3 / 4 / 5-Axis CNC + Turning
Complex structural parts, shafts, housings, and transmission components. Metals and engineering plastics.
ISO 9001:2015
3/4/5-Axis Milling
CNC Turning
CMM Inspection
Global Delivery