Nanhe CNC Processing Service: How to Vet the Supplier

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  Six proven checks, in the order they decide a job
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  Which part belongs on which machine
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  What tolerance is the Nanhe CNC processing service actually quoting
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  Machine capacity behind a Nanhe CNC processing service quote
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  Certifications that matter for your industry
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  MOQ, lead time and the quoting clock
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  Materials and finishes that change the answer
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  What a usable quote contains
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  Step by step: from RFQ to first article

A shop that says ±0.005 mm is telling you what one machine can do on one feature under good conditions. The number that matters is what the process holds across every dimension on the print, on every part in the run. Ask for the tolerance per feature class: bores, slots, flatness, and hole position are not the same problem. A Ø10 H7 bore and a 300 mm bolt circle will not both land at ±0.005 mm without a specific plan.

Position tolerance is where most quotes quietly loosen. True position on a bolt pattern depends on the fixture, the number of setups and whether the datum is accessible. If your print calls 0.05 mm true position across a part that needs three setups, the shop has to either add a fixture or renegotiate the callout. Get that in writing before the PO, not after the first article.

Surface finish travels with tolerance. Ra 0.8–1.6 μm is a normal machined finish and costs nothing extra on most aluminum parts. Ra 0.2–0.8 μm needs a finishing pass, sharper tooling and often a different stepover, so it belongs in the quote as a line item. If the drawing calls Ra 0.4 μm on a deep pocket wall, expect the shop to question it.

We quote ±0.005 mm where the geometry supports it, and we say so when it does not. A print asking ±0.005 mm on a 4,000 mm long part is asking for a different process, not more effort. That conversation is cheaper at the quoting stage than at the inspection report.

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  Ask per featureBore, slot, flatness and position have different cost drivers.
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  Datums drive costA hidden datum forces extra setups and extra fixtures.
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  Finish is a line itemRa 0.2–0.8 μm is a separate operation, not a default.

Capacity is not a marketing number. It is the list of travels and spindle types that can physically reach your part. A 4,000 × 400 × 150 mm travel machine handles long extrusions and base plates. A 750 × 1,150 × 550 mm machine handles most housings. Compact 500 × 500 × 450 mm and 500 × 310 × 200 mm machines are the workhorses for brackets and small bodies. If your part does not fit a travel envelope, no amount of skill fixes it.

Five-axis work is where the setup count drops. A part with undercuts, compound angles or deep cavities that would need four or five setups on a 3-axis machine can often run in one or two on a simultaneous 5-axis center with a Ø400 mm rotary table. Fewer setups means fewer datum shifts, which is where position error accumulates. It also means the first article arrives sooner.

The tradeoff is cost per hour. Five-axis time is more expensive than three-axis time. If your part is a flat plate with holes, putting it on a 5-axis center wastes money. We route simple prismatic work to 3-axis machines and reserve the 5-axis centers for geometry that genuinely needs them. That routing decision is worth asking about in any quote you compare.

For turning work, mill-turn centers combine a lathe and a mill in one platform. Shafts with cross holes, flats or slots avoid a second operation and a second setup. The limit is part size and the number of live tools needed. Beyond that, the part goes back to a mill.

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  Fit comes firstCheck the travel envelope before you discuss tolerance.
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  Setups drive position errorEvery re-clamp adds a datum shift you cannot inspect away.
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  Route by geometryFlat plates on 5-axis centers is a cost mistake.

Certificates are not interchangeable. ISO 9001:2015 is the baseline quality system and covers most industrial machinery, robotics and electronics work. IATF 16949:2016 adds automotive-specific controls: PPAP discipline, traceability, change management. ISO 13485:2016 covers medical device manufacturing and the documentation trail that goes with it. ISO 27001:2022 covers information security, which matters when you upload proprietary CAD to a supplier portal.

Ask for the certificate scope, not just the logo. A certificate can cover one plant or one product family. If your program runs in a plant outside that scope, the certificate does not apply to your parts. The same logic applies to sub-tier processes: anodizing, plating and heat treatment are often outsourced, and the certificate on the wall may not travel with the part.

For automotive programs, ask how the shop handles a deviation. A controlled shipping level, a deviation request or a first-article inspection report should be a documented routine, not a scramble. For medical programs, ask about lot traceability from raw material certificate to final inspection record. Both answers tell you more than the certificate itself.

Upload security is a real purchasing criterion. We keep uploads confidential and sign an NDA on request. If your legal team needs a mutual NDA before drawings leave your network, start that before the RFQ, not after.

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  Match certificate to industryISO 9001 for general, IATF for auto, 13485 for medical.
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  Check the scopeA certificate for another plant does not cover your parts.
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  Traceability is testableAsk for one sample lot record and read it end to end.

A minimum order quantity is a scheduling decision, not a technical one. A shop with flexible fixturing and a mixed-machine floor can run one prototype in the morning and a 10,000-part lot in the afternoon. A shop organized around long runs cannot, and will quote a MOQ to protect its setup time. Ask directly: can you run one piece, and what changes at 100 pieces?

Lead time has three separate clocks. Quoting is the first: a real quote with a DFM note should come back within 12 hours for a defined drawing and material. Production start is the second: once the material is released and the fixture is planned, cutting can begin within 24 hours. Shipping is the third: simple parts ship in 3–5 days. Any quote that collapses these into one number is hiding the risk.

The risk number worth asking about is late delivery history. A supplier that tracks its own on-time rate can tell you the probability of a late shipment. Under 2% is a working number for a shop running mixed-volume work. If a supplier cannot answer the question, they are not tracking it.

Rush work is a routing decision, not a promise. A part that needs five-axis time and anodizing cannot be compressed below the anodizing queue. Ask which steps are on the critical path before you accept a date.

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  Three clocksQuote, production start and shipping are separate promises.
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  MOQ is schedulingOne-off and volume work can share a floor with the right fixtures.
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  Ask for the late rateA tracked number beats a verbal assurance.

Aluminum 6061-T6 is the default for machined prototypes and brackets: stable, weldable, good finish. 7075 machines well but is less weldable and more expensive. 2024 has better fatigue behavior and worse corrosion resistance. Stainless 303 is the free-machining grade, 304 is general purpose, 316L is for corrosive and medical environments, and 17-4PH gives high strength with a heat treatment step. Titanium TC4 (Ti-6Al-4V) machines slowly and needs sharp tooling and low cutting speeds.

Material choice drives lead time more than most buyers expect. Inconel and tool steel cut slowly and wear tooling. Titanium needs specific feeds and speeds and often a finishing pass. If your schedule is tight, moving from titanium to 17-4PH or from Inconel to a stainless grade can save days without changing function. That is a design conversation, and it should happen before the RFQ.

Finishes add a queue. Anodizing, plating, powder coating and black oxide are usually outside processes. Hardcoat anodizing and electroless nickel add thickness, which matters on tight bores. Laser marking has a minimum character height of 1.5 mm; below that, the mark becomes unreadable and the part may fail inspection. Bead blasting changes surface texture and can hide small tool marks, but it also removes sharp edges.

Plastics follow different rules. PEEK holds tolerance and takes heat; POM and PA machine cleanly; ABS and PC are cheaper but move with temperature. Carbon fibre is abrasive and needs diamond tooling. If your part is a plastic housing, the tolerance callouts from a metal drawing often need to be relaxed.

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  Grade matters6061, 304 and 316L behave differently in the same operation.
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  Finish adds a queueOutside processes set the real ship date more often than machining.
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  Watch coating thicknessHardcoat and nickel plating close up tight bores.

A quote is an engineering document. It should list material grade, machine routing, tolerance per feature class, finish, inspection method and the assumptions behind the price. If the drawing is ambiguous, the quote should say so and propose a reading. A price with no assumptions is a price you will argue about after the first article.

The DFM note is the part worth reading. It should flag thin walls, deep pockets with tight corner radii, threads too close to an edge, and features that need a custom tool. A corner radius smaller than the cutter diameter forces either a smaller cutter with a slower feed or an EDM step. Both cost money. Catching that at quoting is cheaper than catching it at inspection.

Inspection scope belongs in the quote too. We inspect 100% of parts before shipment, covering incoming raw material, in-process monitoring and final inspection, with reports on request. If your program needs a full dimensional report, a first-article inspection report or material certificates, list it before the PO. Inspection capacity is planned, not improvised.

Finally, ask what happens when a dimension is out. A shop with a documented nonconformance process will tell you how it isolates parts, notifies you and reworks or replaces them. That process is a better predictor of a working relationship than any single on-time delivery.

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  Assumptions in writingEvery quote should state what it assumed about the print.
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  DFM flags cost driversThin walls and small corner radii are the usual culprits.
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  Name your inspection scopeFAIR, dimensional report and material certs are planned work.