China CNC Machining Service Price: What Actually Drives the Number
This page is for engineers and sourcing staff who compare quotes from Chinese machine shops. We break the quoted number into the factors you can control, show which parts suit which process, and list the checks worth running before you place a purchase order.
In this article
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Key takeaways
How the main cost drivers compare
Typical direction of the effect on unit price when the factor increases.
| Cost driver | Low end | High end | Effect on price |
|---|---|---|---|
| Tolerance | ±0.05 mm | ±0.005 mm | Steep rise, extra finishing ops |
| Surface finish | Ra 1.6–3.2 μm | Ra 0.2–0.8 μm | Moderate to steep |
| Setup count | 1–2 faces | 5+ faces | Steps up per extra setup |
| Material | 6061 aluminium | Inconel, Ti-6Al-4V | Tool wear drives the rate |
| Quantity | 1 prototype | 500+ parts | Setup cost spread thin |
| Inspection | Sample check | 100% + reports | Adds labor, not machine time |
What a China CNC machining service price is built from
A machining quote is a sum of four blocks: programming and fixturing, machine time, material, and finishing plus inspection. Programming is paid once per part number, no matter how many pieces you order. Machine time is paid per piece, and it is the block that moves most when geometry gets hard.
Machine time depends on the volume of metal you remove, not the size of the blank. A 200 × 200 mm plate with a few drilled holes may run in 15 minutes. A 60 mm housing with deep pockets, thin walls and a 0.02 mm true position can run for hours because the shop must take light passes to control deflection.
Material is usually the second largest line. Certified stock with mill test reports costs more than generic bar, and that gap widens for titanium, Inconel and beryllium copper. For regulated work in aerospace or medical devices, traceability is not optional, so budget for it from the start.
Finishing and inspection sit at the end of the quote and are easy to forget. Anodizing, electroless nickel, powder coating and bead blasting are outside operations with their own minimum charges. Full inspection with reports adds labor and can add several days if the shop sends parts out.
- 1Programming and fixturingPaid once per part number; a new fixture for an odd geometry can add real cost.
- 2Machine timeDriven by material removal volume, tool access and the number of setups.
- 3MaterialGrade, certification and stock form (bar, plate, forging) all change the line.
- 4Finishing and inspectionOften subcontracted, with their own minimum charges and lead time.
Which parts are cheap to machine and which are not
Parts with open access from two or three directions are the cheapest to produce. Think brackets, plates, manifolds with shallow pockets and shafts that turn in one setup. If a standard 3-axis vise can hold the blank and a Ø10 mm end mill can reach every face without hitting a wall, the shop runs at full feed and the price stays low.
Cost climbs when the tool cannot reach the feature. Deep pockets with a depth-to-diameter ratio above 4:1 force smaller tools, lower feed rates and more passes. Thin walls below 1.5 mm need support or light cuts to avoid chatter. Both cases add time without adding a single new feature.
Five-axis work is not automatically expensive. A part that would need four setups on a 3-axis machine can often be done in two on a simultaneous 5-axis center, and the savings in fixturing and handling can offset the higher hourly rate. The break-even usually sits around three or more approach directions.
Parts that should not go on a CNC mill at all: large thin panels, simple enclosures and high-volume small brackets. Sheet metal fabrication, die casting or vacuum casting will beat machining on unit price once quantities pass a few hundred pieces. Machining wins on prototypes, tight tolerances and low-volume complex shapes.
- 1Good fit for machiningBrackets, housings, manifolds, shafts, prototypes, low-volume complex parts.
- 2Poor fit for machiningThin panels, simple boxes, high-volume simple parts better suited to casting or sheet metal.
- 3Watch the depth-to-diameter ratioAbove 4:1, tool deflection and chatter start to raise cost quickly.
Where tolerance and surface finish change the number
General machining holds ±0.05 mm without special effort. Tightening to ±0.005 mm requires finishing passes, temperature control, sometimes grinding, and more frequent in-process checks. Only put tight tolerance on the features that need it. A blanket ±0.005 mm note on every dimension raises the price and slows the job without improving function.
Surface finish follows the same logic. As-machined Ra 1.6–3.2 μm is the default from a clean milling cut. Ra 0.8–1.6 μm needs a finishing pass with a sharp tool and stable setup. Ra 0.2–0.8 μm usually means grinding, lapping or polishing, and it can add days if the shop has to send parts out.
Functional surfaces deserve the tight callout. Cosmetic surfaces on a bracket often do not. If a face only needs to sit flat against another part, a flatness callout does more for you than a blanket Ra 0.4 μm note.
Ask the shop which tolerance and finish they quoted against. Two quotes can differ by 30 percent simply because one assumed general tolerance and the other priced every dimension at ±0.01 mm.
- 1General tolerance±0.05 mm, standard tooling, no extra operations.
- 2Precision tolerance±0.005 mm, finishing passes, grinding and tighter inspection.
- 3As-machined finishRa 1.6–3.2 μm, no extra operation.
- 4Fine finishRa 0.2–0.8 μm, may need grinding, lapping or polishing.
How quantity and lead time shift the unit price
Setup cost is fixed. If programming and fixturing take 4 hours, that cost sits on the first piece. At one piece you pay all of it. At 100 pieces you pay 4 percent of it per part. That is the main reason unit prices drop fast between 1 and 100 pieces and then flatten out.
Material buying follows the same curve. Bar stock comes in standard lengths, and a shop that buys a full bar for a 5-piece order has to absorb the remainder. At 500 pieces the material is bought to size and the scrap rate drops.
Lead time and price trade off. A shop with open machine capacity can move a job in 3–5 days. A shop that is booked out may still quote a low price but push the start date. For production runs, confirm the start date in writing rather than assuming the quote implies it.
No minimum order quantity helps prototyping. You can order one piece, check the fit and finish, then scale to a 10,000+ part run with the same supplier and the same fixture. That continuity saves the second round of programming and first-article cost.
- 11–10 piecesSetup dominates the unit price; expect the highest rate per part.
- 2100–500 piecesSetup spreads well; material and machine time dominate.
- 31,000+ piecesConsider casting or forging blanks to cut machining time on simple shapes.
What to verify before you accept a China CNC machining service price
A low quote means nothing if the shop cannot hold the tolerance or ship on time. Check the machine list against your part. A shop with 16 simultaneous 5-axis centers, 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers can take on most geometry. If a supplier cannot name the machine that will run your part, that is a warning.
Check the quality system against your industry. ISO 9001:2015 covers general quality management. IATF 16949:2016 matters for automotive and EV work. ISO 13485:2016 is the one medical device buyers look for. ISO 27001:2022 covers information security, which matters if you share CAD files and drawings.
Ask how inspection is handled. A shop that runs raw material checks, in-process monitoring and a final inspection before shipment is not the same as one that checks the first and last piece. Reports on request are useful for your own quality file.
Finally, confirm the confidentiality terms. Uploads should be handled as secure and confidential, and an NDA should be available on request if your drawings are sensitive. Do this before you send files, not after.
- 1Machine fitMatch the quoted process to a specific machine that can reach your features.
- 2Certification fitISO 9001 for general work, IATF 16949 for auto, ISO 13485 for medical.
- 3Inspection planRaw material, in-process and final checks, not just first and last piece.
- 4ConfidentialitySecure uploads and an NDA available on request before files move.
How to get a comparable quote in seven steps
Each step lists what to send and what to avoid.
- 11. Send STEP and 2D drawings togetherA STEP file alone does not carry tolerance or finish. Add the 2D drawing with GD&T so the shop prices the real requirement, not a guess.
- 22. State the quantity break you planAsk for 1, 10, 100 and 500 piece prices. The curve tells you where setup stops dominating. Avoid asking for a single number.
- 33. Name the material grade and stock form6061-T6 bar is not the same as 6061 plate. For titanium or Inconel, say whether certified stock with mill test reports is required.
- 44. Mark only the critical tolerancesCall out the features that matter at ±0.005 mm and ±0.01 mm. Leave the rest at general tolerance to avoid paying for precision you will not measure.
- 55. Separate finish from machiningList anodizing, plating, powder coating or bead blasting as separate lines, with color and thickness where relevant.
- 66. Ask for the DFM notesA shop that returns DFM feedback within 12 hours is reading your part. Thin walls, deep pockets and tool access issues should appear in those notes.
- 77. Confirm start date and inspection scopeAsk when the machine starts and what inspection is included. Production can start within 24 hours when the file set is complete.
Common questions on machining quotes
Why do two shops quote very different prices for the same part?
They are usually not quoting the same thing. One may have priced general tolerance at ±0.05 mm and the other every dimension at ±0.005 mm. Finishing and inspection can also be inside one quote and outside the other.
Ask each shop to list the tolerance class, material grade, finish and inspection scope behind the number. Once those match, the prices get much closer.
Does a lower unit price mean the shop is cutting corners?
Not always. A shop with the right machine for your geometry can run faster and charge less. A shop that quotes high on every job may simply be busy.
The warning sign is a low price with no DFM feedback and no clear inspection plan. That combination usually shows up as rework or a late shipment.
Should I ask for 5-axis machining to save setups?
Only if your part has features on three or more approach directions. For a part cut from two sides, a 3-axis machine with a good fixture is cheaper and just as accurate.
Above roughly three directions, a simultaneous 5-axis center often wins because it removes handling and re-fixturing error.
How much does surface finish add to the price?
As-machined at Ra 1.6–3.2 μm is included in the machining rate. Moving to Ra 0.8–1.6 μm adds a finishing pass and some time.
Ra 0.2–0.8 μm usually needs grinding, lapping or polishing. That is a separate operation with its own cost and lead time, so apply it only to functional surfaces.
What certifications should a supplier hold?
ISO 9001:2015 is the baseline for general machining. Add IATF 16949:2016 for automotive and EV parts, and ISO 13485:2016 for medical devices.
ISO 27001:2022 covers information security, which matters when you share design files. Ask for the certificate scope, not just the logo.
Can I order one piece before committing to a production run?
Yes. There is no minimum order quantity, so a single prototype can be machined first. Check the fit, tolerance and finish on that piece.
Then scale to a 10,000+ part run with the same fixture and program. That keeps the second round cheaper and more consistent than starting over with a different supplier.
Get a quote you can actually compare
Send your STEP file and 2D drawing. We return a quotation and free DFM analysis within 12 hours, with the tolerance class, material grade and inspection scope written on the quote.
12-hour quoteFree DFM analysisNo MOQ100% inspection before shipment
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