GreatLight CNC Machining Factory: 7 Proven Checks Before You Send an RFQ

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  Key takeaways
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  What to check, and what good looks like
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  Tolerance: what ±0.005 mm actually covers
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  Machine mix and the size envelope
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  Certifications: which one your audit needs
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  Lead time, MOQ and how the quote is built
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  Materials and finishing that fit your application
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  Inspection, traceability and confidentiality
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  7 steps to qualify a supplier in one week

Every supplier page claims tight tolerance. The useful question is which features, on which material, at which size. GreatLight quotes ±0.005 mm (±0.0002 in) as the shop capability, and that number holds on features you can reach with a rigid setup and a sharp tool. On a 40 mm aluminium bracket, that is routine. On a 900 mm steel weldment, thermal drift and tool deflection eat into it.

Tolerance is a system, not a single number. Datum selection, fixturing, tool wear and the inspection method all contribute. If your drawing calls out ±0.005 mm on a bore but the mating part is located from a different datum, the parts may measure in spec and still not assemble. Send the mating drawing or the assembly stack-up with the RFQ.

Surface finish travels with tolerance. A Ra 0.2–0.8 μm finish usually needs a separate finishing pass or a different process than a Ra 1.6–3.2 μm as-machined surface. Specify finish per face, not for the whole part. It changes cycle time and price more than most engineers expect.

Ask for the inspection plan before you place the order. A first article report plus in-process checks on the tight features is normal here. If a supplier cannot describe how they will measure a ±0.005 mm position, the tolerance claim is marketing.

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  Reachable featuresShort, rigid, single-setup features hold ±0.005 mm reliably.
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  Long or thin partsExpect ±0.01 mm or looser unless the setup is redesigned.
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  Finish per faceRa 0.8–1.6 μm on sealing faces only keeps cost down.

A GreatLight CNC machining factory runs 127 high-precision machines across three wholly-owned plants. The split matters more than the total: 16 simultaneous 5-axis machining centers, 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers. Five-axis handles contoured pockets, angled holes and parts that would need four setups on a 3-axis machine. Mill-turn handles shafts and housings with turned and milled features in one cycle.

The size envelope decides whether a shop can take your part at all. Here the largest travel is 4,000 × 400 × 150 mm, with mid-size envelopes of 750 × 1,150 × 550 mm and 600 × 600 × 600 mm, and compact cells at 500 × 500 × 450 mm and 500 × 310 × 200 mm. A Ø400 mm rotary table covers cylindrical work that needs indexing.

Match the part to the cell before you compare price. A part that fits a 3-axis machine with one setup should not be quoted on a 5-axis center. A part with five faces of work should not be pushed onto a 3-axis machine with repeated refixturing. Each refixture adds stack-up error and hours.

If your part is near the edge of an envelope, say so in the RFQ. Travel limits, tool length and fixture clearance often decide feasibility before tolerance does. A quick DFM note from the shop within 12 hours will flag it.

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  5-axisContoured surfaces, angled features, fewer setups.
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  Mill-turnShafts, bushings and housings with mixed features.
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  3-axisPrismatic parts, one or two setups, best hourly rate.
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  Large travelUp to 4,000 mm long parts on the big frame.

Certificates are not decoration. Each one answers a specific question a customer or auditor will ask. ISO 9001:2015 covers the quality management system as a whole. IATF 16949:2016 adds automotive production requirements. ISO 13485:2016 covers medical device quality management. ISO 27001:2022 covers information security, which matters when you send proprietary CAD files.

For industrial machinery and electronics, ISO 9001 is usually enough. Automotive and EV programs typically require IATF 16949, and the paperwork trail that comes with it: control plans, traceability, change notification. Medical device work needs ISO 13485 plus a documented process validation path. If your customer audits your supply chain, send the certificate scope, not just the logo.

ISO 27001 is the one buyers forget. It governs how your drawings, models and revision history are stored and who can access them. For a program with a long development cycle, that matters as much as machining accuracy.

Ask for the certificate number and expiry date, then verify the scope covers machining. A certificate for a trading office is not the same as one for a machine shop. GreatLight holds all four and can share documentation under NDA.

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  ISO 9001:2015Baseline QMS for most industrial work.
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  IATF 16949:2016Required for automotive and EV production parts.
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  ISO 13485:2016Medical device components and instruments.
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  ISO 27001:2022Data security for your CAD and revisions.

Quoting speed tells you how the shop is organized. Here a quotation and free DFM analysis come back within 12 hours, and production can start within 24 hours of approval. Standard parts ship in 3–5 days. Those numbers assume a released drawing, a material that is in stock, and no unresolved DFM questions.

There is no minimum order quantity. One prototype and a 10,000+ part run go through the same intake, inspection and shipping flow. That removes the usual awkward gap where a shop will not quote a single bracket but also will not quote a bridge tool for a run that has not been funded yet.

Read the quote structure, not just the total. A useful quote breaks out material, setup, cycle time, finishing, inspection and freight. If finishing is a single lumped line, you cannot tell whether anodizing is clear or hardcoat, or whether laser marking is included. Ask for the breakdown.

Watch for the two hidden drivers: material availability and finishing queue. A specialty titanium grade or a hardcoat anodize batch can add days that have nothing to do with machining. If your schedule is tight, confirm both before you commit.

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  12-hour quoteIncludes free DFM analysis on the drawing.
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  24-hour startAfter you approve the quote and DFM notes.
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  3–5 day shippingFor standard parts with stock material.
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  No MOQFrom one prototype to 10,000+ parts.

Material choice is usually fixed by the application, but the grade matters. The aluminium list runs 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12. Stainless covers 303, 304, 316, 316L, 420, 430, 431, 440C and 17-4PH. Steels include 1018, 1045, 4130, 4140, 4340, A36 and tool steel. Copper and brass grades run from C101 and C110 to beryllium copper and C36000.

For demanding work there is TA1, TA2, TC4 (Ti-6Al-4V), Inconel and magnesium AZ31B or AZ91D. Plastics cover ABS, PC, PMMA, POM, PA, PEEK, PP, HDPE and carbon fibre. Each of these behaves differently in the cut. Titanium and Inconel need lower cutting speeds and more tool changes, which shows up in cycle time, not in the tolerance.

Finishing options are broad: anodizing in clear, colour, hardcoat or conductive; electroless nickel, zinc, silver and gold plating; powder coating and black oxide; bead blasting, tumbling, brushing and polishing; laser marking and engraving. Laser marking has a minimum character height of 1.5 mm, so plan your part numbers and serials around that.

Pick finishes by function. Hardcoat anodize for wear surfaces, clear anodize for appearance, black oxide for a low-cost dark finish on steel. Do not specify hardcoat on a whole part when only the bore rubs against something.

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  Aluminium6061-T6 and 7075 cover most structural parts.
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  Titanium and InconelExpect slower cycle times, not looser tolerance.
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  Laser markingMinimum character height 1.5 mm.

Inspection is where a tolerance claim becomes evidence. Raw material is checked on receipt, dimensions are monitored during the run, and every lot gets a final inspection before shipment. That final step is 100%, not a sample. Inspection reports are available on request, and a first article report is the normal starting point for a new program.

The historical qualification rate is 99.99%, and the historical late-delivery probability is below 2%. Those are shop records, not a guarantee for your order. Treat them as a signal about process stability, then set your own buffer for the schedule.

Traceability matters more as volumes grow. Ask how material lots, machine logs and inspection results are linked to a shipment. For automotive and medical programs, that link is often the difference between a clean audit and a corrective action.

Confidentiality is part of the same conversation. Uploads are handled as secure and confidential, and an NDA is available on request. If your drawing set includes a full assembly, sign the NDA before you send the top-level model, not after.

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  100% inspectionEvery lot measured before shipment.
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  Reports on requestFirst article and dimensional reports.
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  NDA on requestSign it before sending assembly models.