China CNC Processing Wholesale Transaction

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  What a CNC processing wholesale transaction actually prices
• 2
  How a wholesale order is built and released
• 3
  Which parts suit wholesale buying, and which do not
• 4
  Where quality is won or lost in a batch run
• 5
  Matching batch size and process to the part

A wholesale CNC order is not a discount on a prototype. It is a different cost structure. On a one-off part, almost everything you pay for is setup: programming, workholding, first-article checks. On a batch, those costs are spread across the run, so the price per part is decided by cycle time plus material, not by setup.

This is why the same drawing can look expensive at quantity 1 and reasonable at quantity 500. The machine still needs to be programmed once. The fixture still has to be built once. What changes is how many parts carry that cost.

A supplier quoting a China CNC processing wholesale transaction usually splits the number into four lines: material, machining cycle, finishing, and inspection. Ask for that split. If a quote arrives as one lump figure, you cannot tell whether the saving came from cycle time, from cheaper stock, or from skipping a deburring step.

Volume only helps where setup is a real share of the cost. On a simple turned bushing, setup may be 20 minutes against a 90-second cycle, so quantity 200 already flattens the curve. On a complex five-axis housing, setup and fixture design can run for hours, and the per-part cost keeps falling well past quantity 1,000.

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  Setup is fixedProgramming, fixture and first article do not repeat per part.
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  Cycle time repeatsRoughing, semi-finish and finishing passes scale with quantity.
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  Material scales with scrapBar end, plate margin and rejected blanks all count.
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  Inspection can be sampled or 100%Say which one you want before the quote is fixed.

Most wholesale machining runs move in stages rather than one big shipment. A typical sequence is a small pilot batch cut on the final fixture, a dimensional report on those parts, then release of the balance. The pilot is not a prototype: it comes off the same machine and the same program as the full run.

That structure exists because the risky moment in any batch is the first hour of cutting. Thermal drift on a long run, tool wear after a few hundred parts, and chip evacuation inside deep pockets all show up early. Catching them on 20 parts is cheaper than catching them on 2,000.

Tool wear is the quiet variable. A carbide end mill cutting 6061 aluminium may hold size for thousands of parts. The same tool in 17-4PH stainless starts drifting much sooner, and the operator compensates at the control. Good suppliers log that compensation. If nobody is watching it, the last parts in a run are the ones that fail.

Material certificates should be tied to the batch, not to the order. Heat numbers on the mill certificate let you trace which parts came from which bar. For aerospace, medical and automotive work this is not paperwork for its own sake; it is what lets you isolate a problem later without scrapping the whole delivery.

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  Pilot batch firstSame fixture and program, small quantity, measured before release.
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  Trace by heat numberMatch material certificates to the specific lot of parts.
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  Watch compensationTool offsets drift faster in stainless and titanium than in aluminium.

Batch sourcing pays off when the geometry is stable and the material is common. Aluminium 6061-T6, 7075, 304 stainless and POM are stocked widely in China, so lead time is short and stock cost is predictable. Parts that fit inside a 750 × 1,150 × 550 mm envelope can run on several machines, which keeps scheduling flexible.

Parts that need four or five faces machined in one setup are a different case. A single five-axis cycle removes the re-fixturing error that stacks up across three separate operations. On a bracket with true-position holes on four faces, that is the difference between holding ±0.005 mm and chasing it. Batch size does not fix a tolerance problem caused by too many setups.

There are parts that should not go wholesale. Anything still changing weekly belongs in prototyping until the design freezes. Very large single pieces, close to the 4,000 mm travel limit, tie up one machine and rarely benefit from volume. And parts with a cosmetic surface that the customer inspects by eye need a finishing agreement up front, not a default deburr.

Thin-wall aluminium parts are a common trap. Wall sections under about 1 mm deflect under cutting force, and the deflection changes as the part gets lighter through the run. A batch of 500 thin-wall housings can hold size on part 10 and drift on part 400. Discuss wall thickness at the DFM stage, not after the first delivery.

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  Good fitStable geometry, common alloy, envelope under 750 × 1,150 × 550 mm.
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  Good fitMulti-face features that need one five-axis setup.
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  Poor fitDesigns still changing between weeks.
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  Poor fitWalls under 1 mm or cosmetic surfaces with no agreed standard.

In a batch, quality stops being a final inspection question and becomes a process control question. The supplier checks incoming bar stock, monitors the cut, and inspects at the end. If the middle step is missing, the first time anyone measures a bad feature is after the run is finished.

GreatLight runs raw material checks, in-process monitoring and a full inspection before shipment, with dimensional reports available on request. The tolerance floor is ±0.005 mm (±0.0002 in) and surface finish ranges from Ra 0.2–0.8 μm on fine work to Ra 1.6–3.2 μm as machined. Ask which grade your drawing actually needs, because specifying Ra 0.4 μm on a non-sealing face adds cost for nothing.

Certification matters when your own customer audits you. ISO 9001:2015 covers general process control, IATF 16949:2016 applies to automotive work, ISO 13485:2016 to medical devices, and ISO 27001:2022 to information security around your files. None of these guarantee a good part, but they document that the process is defined and repeatable.

Sampling plans should match the risk. A 10,000-part run of a non-critical spacer does not need every part on a CMM. A 200-part run of an implant fixture does. Write the sampling level into the purchase order so there is no argument later about what "inspected" meant.

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  Incoming materialCheck alloy, temper and heat number against the certificate.
• 2
  In-processMeasure at set intervals so drift is caught mid-run.
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  FinalDimensional report plus visual and finish check.
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  Traceable recordsKeep reports tied to the lot, not just to the order.