China CNC Processing Wholesale Service: What Engineers Should Check First

Wholesale pricing in China comes from spreading setup over many parts, not from cutting corners on the cut. The first decision is machine type, because it sets both cycle time and the number of fixtures you need. A part with features on five faces is usually cheaper on a simultaneous 5-axis center than on three separate 3-axis setups, even though the hourly rate is higher.

For prismatic parts with features on one or two faces, 3-axis milling is still the fastest route. We run 27 three-axis machines for that work, with travels of 500 × 500 × 450 mm and 500 × 310 × 200 mm. Add a fourth axis when you need holes on a cylinder or a shaft with flats, and the part can often be finished in one chucking instead of two.

Long parts change the picture. Our largest travel is 4,000 × 400 × 150 mm, which covers extrusion profiles, long brackets and frame rails. Medium work fits the 750 × 1,150 × 550 mm and 600 × 600 × 600 mm envelopes. If a drawing sits between two envelopes, check the fixture before the machine: a 4,000 mm part on a short bed usually needs more support than the travel figure suggests.

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  One-off or prototype3-axis or 4-axis, minimal fixturing, fastest to first article.
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  Five-face geometrySimultaneous 5-axis cuts setups, holds position across faces.
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  Turned features plus millingMill-turn centers finish both in one operation.
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  Parts over 1,200 mmLong-bed machines; confirm support and deflection first.

A ±0.005 mm callout is achievable on critical features, but it is not a blanket tolerance for every dimension on a drawing. What matters is which features carry the tight callout and how they are fixtured. A bore referenced to a single datum in one setup holds far better than the same bore measured across three repositioning steps.

Surface finish follows the same logic. As-machined surfaces land around Ra 1.6–3.2 μm. Fine finishing reaches Ra 0.2–0.8 μm on sealing faces and bearing bores, usually with a separate light pass. If you need that finish on a deep pocket, say so on the drawing, because tool reach limits which surfaces can be reached at all.

Inspection closes the loop. We check raw material on receipt, monitor dimensions in process, and inspect 100% of parts before shipment. Reports are available on request, including CMM data for tight features. A 99.99% qualification rate is what we measure across shipped lots, and it depends on those three checkpoints staying in place when volume rises.

Two parts with identical geometry can differ by a large margin in cost because of stock availability and machinability. Aluminum 6061 and 6082 cut fast and hold good finish, which makes them the default for housings, brackets and fixtures. 7075 machines well too but costs more and is less weldable. If you need corrosion resistance in aluminum, 5052 and 5083 are the marine-grade picks.

Stainless is where drawings often go wrong. 303 is the easiest to machine and is fine for shafts and fittings. 304 and 316 hold up better in corrosive service but work-harden, so feeds and speeds need care and cycle times rise. 17-4PH (SUS630) gives high strength after heat treatment. For medical and food-contact parts, 316L is usually the specified grade.

Titanium and nickel alloys belong in a different cost band. TC4 (Ti-6Al-4V) and Inconel cut slowly and wear tooling, so they suit low-volume, high-value parts rather than volume runs. On the plastics side, POM and PA are stable and machine cleanly, while PEEK and carbon fibre filled grades cost more and need sharp tooling to avoid delamination or burrs.

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  Aluminum6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075, ADC12.
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  Stainless303, 304, 316, 316L, 420, 430, 431, 440C, 17-4PH (SUS630).
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  Steel1018, 1045, 4130, 4140, 4340, A36, tool steel.
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  Titanium and specialTA1, TA2, TC4, Inconel, magnesium AZ31B / AZ91D.

A wholesale order starts with a drawing and a quantity, not a catalog number. Send the 3D model and 2D drawing with tolerances, and we return a quotation plus a free DFM analysis within 12 hours. That DFM pass is where most of the savings appear: a wall thickness change or an added fillet can remove a second setup or a special tool.

Once the process is fixed, production can start within 24 hours. Parts normally ship in 3–5 days for standard volumes, and our historical late-delivery probability is below 2%. There is no minimum order quantity, so a single prototype and a 10,000+ part run go through the same quoting path. That matters when a design is still moving and you need parts to test before committing.

Finishing and assembly sit under the same roof across three wholly-owned plants covering 7,600 m². Anodizing, plating, powder coating, black oxide, bead blasting and laser marking are all handled internally, which removes the shipping and scheduling gaps that appear when a finishing vendor is a separate company. Uploads are kept confidential, and an NDA is available on request.

Certificates tell you which management systems are audited, not which part you will receive. GreatLight holds ISO 9001:2015 for general quality management, IATF 16949:2016 for automotive work, ISO 13485:2016 for medical devices, and ISO 27001:2022 for information security. The last one matters if your drawings and CAD files are sensitive.

For aerospace, automotive and medical buyers, the practical question is traceability. We keep material certificates tied to the lot, record in-process measurements, and can issue inspection reports with the shipment. If your program needs first article inspection reports or PPAP-style documentation, state that at quoting time, because it changes the inspection plan.

The 150 technicians across our Dongguan and Singapore sites work on parts for aerospace, automotive and EV, medical devices, robotics, electronics, industrial machinery and new energy equipment. Different industries carry different defaults: medical leans on 316L and fine finishes, EV leans on aluminum housings and busbars, robotics leans on tight bore alignment across mating parts.