China Wholesale CNC Processing for Complex Metal Parts

Wholesale here means batch economics, not cheap parts. You send one set of drawings, and the quote covers the first article plus the repeat runs. At GreatLight that range starts at a single prototype and runs past 10,000 pieces, with no minimum order quantity. The setup cost gets spread across the lot, so unit price falls as quantity rises. Nothing about the drawing changes.

The practical difference is how the shop schedules. A one-off job can be squeezed onto any free spindle. A 5,000-piece run needs fixture design, gauge planning and a stable inspection loop before the first chip is cut. That preparation is where the money goes, and it is also what keeps dimensions repeatable from lot to lot.

Tooling is the other variable. Long runs often justify a soft jaw or a dedicated fixture, which costs more up front and less per part. If your design is still moving, keep the batch small. Once the revision stops changing, the fixture pays for itself quickly.

Three-axis milling cuts along X, Y and Z with the part fixed. It handles plates, blocks, brackets and pockets with open faces. Add a fourth axis and you can index the part to reach the other sides without a second setup. Five simultaneous axes go further: the tool stays normal to a curved surface while it moves, so undercuts, deep cavities and compound angles come off in one pass.

The trigger is usually setup count, not shape. If a part needs four or more orientations, each one adds a fixture, an operator step and a chance for position error to creep in. Machining it on a five-axis center removes those handoffs. Position tolerance between features stops depending on how well the operator re-clamped the block.

Not every job belongs on a five-axis machine. Prismatic parts with simple geometry run faster and cheaper on a three-axis mill. Long, round parts belong on a lathe or a mill-turn center. Five-axis work pays off when the geometry is truly three-dimensional, the tolerance stack is tight, or the surface finish has to be continuous across a curve.

GreatLight runs 16 simultaneous five-axis machining centers, 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers. Maximum processing size reaches 4,000 mm. Large travels cover 4,000 × 400 × 150 mm; medium frames run 750 × 1,150 × 550 mm and 600 × 600 × 600 mm; compact machines handle 500 × 500 × 450 mm and 500 × 310 × 200 mm. A Ø400 mm rotary table covers round work.

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  Use five axes whenDeep cavities, undercuts, compound angles, or four-plus setups on three-axis.
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  Stay on three axes whenFlat plates, open pockets, loose tolerances, and high volume of simple cuts.
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  Use mill-turn whenThe part is mostly cylindrical with milled flats or cross holes.

A tolerance is only meaningful with a process behind it. GreatLight works to ±0.005 mm (±0.0002 in) on qualified features. That number is not a default for every dimension on the drawing. It applies where the feature, the material and the fixturing allow it, and it is verified by inspection rather than assumed.

Thermal drift is the quiet enemy on tight work. Aluminium moves as the spindle warms and as the shop temperature shifts through the day. On long runs we cut, measure, and adjust offsets rather than trusting the first article. For titanium and Inconel, tool wear moves the cut more than temperature does, so tool changes are scheduled by time or by part count.

Surface finish follows the same logic. The as-machined range is Ra 1.6–3.2 μm. A high-finish pass gets you to Ra 0.8–1.6 μm, and fine work reaches Ra 0.2–0.8 μm. Finer finishes cost time because the stepover shrinks and the tool path gets longer. Specify the finish per surface, not for the whole part.

A 99.99% qualification rate across shipped lots comes from checking every part, not sampling. Incoming material is verified, dimensions are monitored during the run, and a final inspection happens before anything is packed. Inspection reports are available on request.

Machining is rarely the last step. Anodizing comes in clear, colour, hardcoat and conductive versions. Plating covers electroless nickel, zinc, silver and gold. Powder coating and black oxide handle wear surfaces and appearance parts. Bead blasting, tumbling, brushing and polishing set the cosmetic baseline. Laser marking and engraving are available down to 1.5 mm character height.

Finishes interact with tolerances. Anodizing builds a coating on the surface, which can push a dimension past its limit if the drawing calls for a tight fit. Tell us which surfaces are functional and which are cosmetic. Hardcoat on a bearing bore is a problem; hardcoat on a housing face is usually fine.

Documentation matters as much as the cut when parts cross a border. Material certificates, dimensional reports and inspection records travel with the shipment. If your quality team needs a specific report format, say so at quoting. Rebuilding a report three weeks later wastes everyone's time.

Uploads stay confidential and an NDA is available on request. For programs where the drawing itself is sensitive, we can keep the file set restricted to the engineers assigned to the job.