China Wholesale Large Scale CNC Processing Services

A large part is not simply a small part scaled up. On a machining center, three numbers set the boundary: X, Y and Z travel of the spindle, the load the table can carry, and the reach of the tool beyond the spindle nose. GreatLight runs travels of 4,000 × 400 × 150 mm on the largest frames, with 750 × 1,150 × 550 mm and 600 × 600 × 600 mm on the mid-size machines. If your part fits inside one of those boxes, size itself is rarely the problem.

The real constraint is stiffness. A long thin rib, a plate with a deep pocket, or a housing with a thin wall will deflect under cutting load no matter how large the machine is. Machinists compensate with lighter depth of cut, support under the workpiece, or a change in setup orientation. That is a process decision, so send the 3D model rather than a 2D outline. We can see wall thickness and unsupported spans before quoting.

Weight also matters. A heavy casting or a thick steel plate needs lifting gear and a table that will not sag. On a 4,000 mm frame, a small sag under load becomes a visible error at the far end of the part. Fixture design is often a bigger share of the setup time than the cutting itself on large work.

For 5-axis work, the rotary table is Ø400 mm. Parts that need simultaneous 5-axis motion at the outside of that envelope will not fit, even if the linear travels allow the part. Check the feature that needs the tilt, not just the overall part size.

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  Travel box firstConfirm the part sits inside X, Y and Z travel with tool clearance.
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  Wall thicknessThin walls and deep pockets set the real cutting limit, not part length.
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  Unsupported spansLong overhangs need support or a different setup orientation.
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  Rotary tableSimultaneous 5-axis features must fit within Ø400 mm.

Tolerance is a thermal question as much as a machine question. A 1,000 mm aluminium part grows about 0.023 mm per 1 °C of temperature change. Cutting generates heat, coolant pulls it away, and the shop floor drifts through the day. GreatLight works to ±0.005 mm and inspects in a temperature-stable area, but the drawing has to support that. If a bore and a mating bore sit 800 mm apart, the tolerance between them should be stated as a relationship, not as two independent ±0.005 mm callouts.

For wholesale runs, the first article is the anchor. We cut one part, measure it fully, and compare the numbers against the model before the rest of the batch starts. If a dimension trends toward one side of the band, the machinist offsets the tool and the run stays centered. That is how a 10,000-part order holds the same tolerance as part one.

Not every feature needs the tight number. A mounting face at Ra 0.8–1.6 μm is normal for a sealing surface. A clearance hole at ±0.1 mm costs less to make and is easier to inspect. Marking only the critical dimensions on the drawing usually lowers unit cost without touching function.

Surface finish follows the same logic. As-machined Ra 1.6–3.2 μm covers most structural faces. Fine finish at Ra 0.2–0.8 μm is for bearing seats, seal faces and sliding surfaces, and it needs a separate finishing pass. Specify it where it matters.

Aluminium is the default for large frames and housings. 6061-T6 machines fast and stays stable, and 7075 gives higher strength where weight matters. 5083 and 6082 are common for welded assemblies that get machined afterward. Aluminium also moves more with temperature, so a large aluminium part benefits from a roughing pass, a pause to cool, and a finishing pass.

Stainless 304 and 316L are used for food, medical and marine hardware. They work-harden, so a light feed and a sharp tool matter more than on aluminium. 17-4PH (SUS630) is the choice when you need strength plus corrosion resistance and can accept heat treatment. On a large stainless part, the extra cutting time is real, so plan the batch around it.

Steel covers 1018 and 1045 for general parts, 4130 and 4140 where strength is needed, and 4340 for highly loaded components. Tool steel appears in dies and wear parts. Titanium TA2 and TC4 (Ti-6Al-4V) are used in aerospace and medical work; they cut slowly and need rigid setups. Inconel is reserved for high-temperature parts where the cost is justified.

Plastics behave differently. POM and PA are stable and machine cleanly. PEEK handles heat and chemicals but costs more than most metals in the same volume. ABS and PC are common for covers and brackets. Carbon fibre reinforced stock wears tools fast, so tool life should be part of the quote discussion.

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  Aluminium6061, 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 (Ti-6Al-4V), Inconel, magnesium AZ31B / AZ91D

A large part is expensive to scrap, and a batch of them is worse. Inspection starts before cutting: raw material certificates are checked against the drawing, and the stock is measured for size and condition. In-process checks run during the cut so a trend is caught while there is still material to remove. Final inspection happens before shipment on 100% of parts.

Reports are available on request. For a wholesale order, a first article inspection report plus dimensional data at a set sampling rate is usually the right level. If the part is a safety item, add material traceability and heat lot numbers to the drawing notes.

We hold ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022. The last one covers information handling, which matters when your models and drawings sit on someone else's server. Uploads are treated as confidential, and an NDA is available on request.

Historical late-delivery probability on our orders is below 2%. That number is not a promise for every job, but it reflects how we plan. Long-lead material is identified at quote, not after the order.

Send a STEP or Parasolid model plus a 2D drawing with the critical dimensions, datums and finish callouts. The model tells us the geometry; the drawing tells us what you will measure. If the two disagree, the drawing usually wins, so keep them in sync.

State the annual quantity, the first order quantity, and whether the volume could change. A 200-piece order and a 10,000-piece order get different fixture plans and sometimes different processes. Tell us the material and temper, the finish, and any marking requirement. Laser marking has a minimum character height of 1.5 mm, so small text on a large part needs a note.

Say where the part goes and what it does. A bracket inside a machine enclosure and a bracket on a moving vehicle are not the same job, even with identical drawings. That context changes how we plan fixtures, inspection and packaging.

We quote with a free DFM analysis within 12 hours. Production can start within 24 hours once the drawing, material and finish are locked, and parts ship in 3–5 days for standard work. There is no minimum order quantity, so a single prototype and a 10,000-part run both fit. Send the file and we will tell you what we would change before cutting metal.

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  Model and drawingSTEP or Parasolid plus 2D drawing with datums and finish callouts.
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  QuantitiesAnnual volume, first order, and how firm the forecast is.
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  Material and finishGrade, temper, coating, and any marking or traceability note.
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  FunctionWhere the part sits and what load or environment it sees.