Bao’an district holds one of the highest concentrations of contract CNC machining shops in southern China. The cluster runs from one-man job shops up to factory-scale operations with twenty or more 5-axis machines, all within a 20km radius of any Shenzhen hotel. Secondary finishing (anodising, passivation, electroplating, polishing, silk-screening, laser engraving) sits inside the same radius. You can quote a part on Monday, hold a CMM-inspected first article on Friday, and have 500 finished parts boxed two weeks later.
What this covers
This page covers subtractive machining of metals and engineering plastics: 3-axis and 5-axis milling, turning (lathe work), mill-turn, and secondary processes. It covers 6061-T6 and 7075 aluminium, brass (C360, C260), 304 and 316 stainless, POM, PEEK, PTFE, and titanium grades 2 and 5. It does not cover sheet-metal fabrication (laser cutting, bending, welding, a separate Dongguan cluster), die casting (separate page), or Swiss-style ultra-precision micro-turning under 3mm diameter.
What Shenzhen and the PRD do well
- MOQ of one. Most Bao’an shops will quote a single prototype as readily as a batch of 500. The quick-turn pricing premium is modest, typically 30–60% over per-unit production cost, because they panel small jobs together on a shared setup.
- Speed plus finishing. A part that takes 7–14 days in a Western prototype shop ships in 3–10 days in Shenzhen including anodising, because the anodise tank is a 15-minute drive away rather than a four-day shipping leg.
- Material breadth. Stock for 6061-T6, 304 stainless, brass, POM, and PEEK sits in warehouses around the cluster. Titanium and 7075 need 2–3 day lead time but rarely longer.
- Operator depth. Experienced machinists are a moat. Complex 5-axis programs that take days to develop in a smaller market get debugged in an afternoon.
Sub-categories
| Sub-category | Typical use | Materials | Tolerance band |
|---|---|---|---|
| 3-axis milling | Brackets, plates, housings, manifolds | All | ±0.05mm typical |
| 5-axis milling | Complex housings, impellers, undercuts | All | ±0.02mm achievable |
| Turning (lathe) | Shafts, pins, threaded fittings | Metals + POM/PEEK | ±0.02mm on diameter |
| Mill-turn | Shafts with cross-features in one setup | Metals | ±0.02mm |
| EDM (wire + sinker) | Sharp internal corners, hardened tool steel | Hardened steels | ±0.005mm |
| Hard milling | Post-heat-treat finishing of tool steel | H13, D2, etc. | ±0.01mm |
MOQs and lead times
| Spec | Sample MOQ | Sample LT | Production MOQ | Production LT |
|---|---|---|---|---|
| 3-axis aluminium, palm-sized | 1 | 3–5 days | 50 | 10–15 days |
| 5-axis aluminium, complex | 1 | 5–10 days | 50 | 14–21 days |
| Stainless 304/316 | 1 | 5–7 days | 50 | 14–21 days |
| Titanium grade 5 | 1 | 7–10 days | 50 | 21–28 days |
| POM / PEEK | 1 | 3–7 days | 50 | 10–18 days |
| Anodising (Type II) | +2 days | +2 days | — | +3–5 days |
| Anodising (Type III hard) | +3–5 days | +3–5 days | — | +5–7 days |
| Passivation (stainless) | +1–2 days | — | — | +2 days |
| Electroplating (Ni, Cr, Zn) | +3–5 days | — | — | +5–7 days |
Price bands
All prices at the stated quantity, ex-works Shenzhen, May 2026. USD conversions at ¥7.2. Pricing is for a “palm-sized” reference part: roughly 80×60×30mm with 6–10 features.
| Material / process | 1 unit | 100 units | 1,000 units |
|---|---|---|---|
| 6061-T6, 3-axis, as-machined | ¥250–500 (USD 35–70) | ¥35–80 (USD 4.85–11.10) | ¥18–40 (USD 2.50–5.55) |
| 6061-T6, 5-axis | ¥450–900 (USD 62–125) | ¥60–140 (USD 8.30–19.45) | ¥30–70 (USD 4.15–9.70) |
| 304 stainless, 3-axis | ¥400–800 (USD 55–111) | ¥70–160 (USD 9.70–22) | ¥35–80 (USD 4.85–11) |
| 316 stainless, 3-axis | ¥500–1,000 (USD 70–140) | ¥85–200 (USD 12–28) | ¥45–100 (USD 6.25–14) |
| Titanium grade 5 | ¥1,200–2,500 (USD 165–345) | ¥250–500 (USD 35–70) | ¥130–280 (USD 18–39) |
| POM (Delrin) | ¥150–350 (USD 21–48) | ¥25–55 (USD 3.50–7.65) | ¥12–30 (USD 1.65–4.15) |
| PEEK | ¥800–1,800 (USD 110–250) | ¥180–420 (USD 25–58) | ¥100–240 (USD 14–33) |
| Type II anodise (any colour) | +¥15–40 | +¥3–8 | +¥2–5 |
| Type III hard anodise | +¥40–100 | +¥10–25 | +¥6–15 |
Specs to lock down
- Material grade and temper (6061-T6 vs 6063-T5 makes a real difference)
- Critical tolerances called out individually; general tolerance per ISO 2768-m or -f for the rest
- Surface finish in Ra (Ra 1.6 default, Ra 0.8 for cosmetic faces, Ra 0.4 needs separate polish step)
- Edge condition: deburr all edges, break sharp edges 0.2×45°, or specific chamfers
- Threads: tapped to standard (ISO metric, UNF) with class (6H typical), or helicoil insert
- Heat treatment if any (T6 for 6061, solution + age for 7075)
- Secondary finishing: anodise type and colour with Pantone reference, plating spec, passivation per ASTM A967
- Marking: laser, silk-screen, or stamped, with artwork file
- Inspection: which dimensions are CMM-critical, AQL for visual cosmetics, packaging spec
Process
- Quote against a fully dimensioned drawing plus STEP file. Verbal “make it like the picture” quotes always go wrong.
- DFM review. Expect feedback on internal corner radii, deep pockets, thin walls, and tool-access constraints.
- First article: one part fully machined and finished, CMM-inspected against the drawing, photos provided.
- Sign-off, then production batch.
- In-process inspection on first piece of every shift and a sample plan thereafter.
- Final 100% visual + AQL dimensional sampling, with CMM report on a sampling plan.
- Pack, label, ship.
QC specifics
- CMM (coordinate measuring machine) report on the first article, with each critical dimension called out. Demand the raw probe data, not just pass/fail.
- Surface roughness measurement (Mitutoyo SJ-210 or similar) on cosmetic and sealing faces.
- Hardness testing on heat-treated parts (Rockwell B for aluminium, Rockwell C for steels).
- Salt-spray test (ASTM B117) on anodised or plated parts when corrosion resistance matters. 96-hour test is the practical default.
- Material certificate for every batch; spot XRF verification for high-stakes parts.
- Witness samples: keep one finished, signed-off part per production lot for future reference disputes.
What goes wrong
- Material substitution. Mitigation: mill cert per batch, spot XRF testing, written approval required for any change.
- Anodise colour drift between batches. Mitigation: lock a physical colour swatch, demand colour-matched first article from every new batch, accept ±2 dE under D65 lighting.
- Tolerance stack on multi-setup parts. Mitigation: prefer 5-axis when more than three setups would otherwise be required, demand CMM verification of feature-to-feature relationships.
- Thread damage from over-torqued taps. Mitigation: specify thread class (6H), require thread plug gauge testing, use helicoil inserts in soft alloys for repeated assembly.
- Sharp burrs on internal features. Mitigation: specify “all edges deburred, no sharp burrs” explicitly, inspect with a gloved hand on the first article.
- Hard-coat anodise dimensional buildup not accounted for. Mitigation: subtract 50µm per surface from machined dimensions before anodising, or specify “machine after anodise” for critical tolerances.
- Polishing scratches under anodise. Mitigation: require 600-grit minimum surface prep before anodise on cosmetic faces, reject parts with visible witness lines under raking light.
Certifications
- Material certificates (3.1 per EN 10204) for metals. Standard, demand them.
- RoHS / REACH for plating and anodising chemistries.
- ISO 9001 is table-stakes; most Bao’an CNC shops above ~20 employees have it. Verify with the cert number.
- AS9100 for aerospace, ISO 13485 for medical, IATF 16949 for automotive narrows the supplier pool sharply and adds 15–30% to unit cost; only specify when end-customer demands it.
- NADCAP for heat treatment and special processes in aerospace is niche. The few Shenzhen shops that hold it are worth knowing about.
Trade shows
- HKTDC Electronics Fair (April, October). Not CNC-specific, but most CNC shops also do enclosures for electronics customers and exhibit here.
- Canton Fair Phase 1 (April, October). Broad industrial machinery; CNC service shops less prominent than equipment makers.
- ELEXCON (Shenzhen, late summer). Useful for finding shops servicing the electronics ecosystem.
- CIMT / CCMT (Beijing or Shanghai, biennial). Equipment-side, but a useful way to gauge what machines your suppliers run.
- Bao’an open factory days. Informal but worth asking your sourcing partner about; many shops will host pre-arranged visits during the spring and autumn sourcing seasons.
When to use us
CNC machining is one of the categories where remote sourcing works well. Drawings, STEP files, and CMM reports travel cleanly. The sourcing desk handles shop shortlisting, drawing scrubbing, DFM negotiation, and first-article review without anyone needing to fly. To walk Bao’an shop floors, see machines run, and sit in on DFM conversations face to face, the hardware founder tour is the in-person version.
Last reviewed: 23 May 2026.
Frequently asked questions
Do I need 5-axis or is 3-axis enough?
3-axis covers most parts you'll ever design: brackets, housings, plates, manifolds with straight bores. 5-axis becomes necessary when you have undercuts, compound angles, contoured surfaces that would otherwise need multiple setups and risk tolerance stack-up, or impeller-style organic geometry. Ask the Bao'an CNC shop to quote both. If 5-axis is less than 1.5× the 3-axis price, take it; you save setup time, tolerance drift, and rework risk.
What's the real difference between Type II and Type III anodising?
Type II is decorative and mildly protective: 5–25µm thick, dyeable in any colour, suitable for consumer enclosures. Type III (hard coat) is 25–100µm thick, much harder (60+ HRC equivalent surface), grey or black only without dye, and adds dimensional buildup that affects tight tolerances. Use Type II for cosmetics; use Type III for wear surfaces, sliding parts, or anything that needs to survive scrubbing. Hard coat adds ¥10–25 per part vs ¥3–8 for Type II at typical volumes.
How tight a tolerance can Shenzhen CNC shops hold?
A competent Bao'an CNC shop with a calibrated machine and a skilled operator will hold ±0.02mm on a single feature, ±0.05mm on most functional fits, and ±0.1mm comfortably on general dimensions. Below ±0.01mm you need grinding or jig-bore work and a specialised shop; fewer of those exist, and they cost 2–4× more. Spec only the tolerances you need. Over-tolerancing is the fastest way to inflate a CNC quote.
Why do quotes for the same part vary 3× between Shenzhen shops?
Three reasons. First, some shops have 5-axis or twin-spindle machines that compress your part into one or two setups; others need four or five and price the labour accordingly. Second, the cheapest quotes often assume general tolerances and no inspection; they'll quietly skip the CMM and ship to-print or near-it. Third, secondary finishing (anodise, passivation, laser engraving) is sometimes bundled, sometimes sub-contracted with a markup. Always quote against the same drawing, the same tolerance table, and the same inspection requirement.
Should I use POM or PEEK if I need a plastic CNC part?
POM (Delrin / acetal) is the workhorse: cheap, stable, machines like butter, low friction. Use it for gears, bushings, low-load mechanical parts. PEEK is the high-end choice: stable to 250°C, chemically inert, biocompatible grades available, but 10–20× the material cost and harder to machine cleanly. Reserve PEEK for medical, aerospace, or high-temperature applications. A Bao'an CNC shop with PEEK experience will quote it confidently; one without will pad heavily and risk delamination.
How do I verify the material is 6061-T6 and not generic aluminium?
Demand a mill certificate for every batch; it should name the alloy, temper, lot number, and supplier. For high-stakes parts, send one part out for a spectroscopic XRF test (¥200–500 in Shenzhen) to confirm the alloy composition matches. Substituting 6063 or generic alloy for 6061-T6 happens; it's softer, anodises differently, and fails fatigue tests sooner. Mill certs plus spot XRF is a 1% cost adder that prevents an expensive recall.