CNC Pricing Guide for Engineers and Buyers

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  Key takeaways
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  What moves a CNC price up or down
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  Material choice sets the baseline cost
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  Tolerance and surface finish: where price jumps
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  Geometry and setup time on low volumes
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  Volume, finishing and inspection lines
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  What to verify before you trust a quote
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  Step by step: how to compare CNC quotes fairly

Material affects price twice: once as stock, once as machining time. Aluminium 6061 cuts fast, throws chips cleanly and tolerates aggressive feeds. Titanium TC4 (Ti-6Al-4V) and Inconel cut slowly, generate heat and wear tools, so the same pocket can take three to five times longer. That gap shows up in the hourly rate, not in the material invoice.

Stock form matters too. A part machined from bar stock wastes material but needs no fixturing beyond a vise. A part machined from plate may need a soft jaw set or a custom fixture, which adds setup hours. When you send a drawing, include the stock form you expect so the supplier quotes the same starting point.

For prototypes, choose a material that is easy to machine and easy to source. Aluminium 6061-T6, 7075 and brass C36000 cover most functional prototypes. Move to stainless 17-4PH or titanium only when the test requires that strength, corrosion resistance or weight. It is common to see a prototype cost cut in half just by switching from titanium to 6061 for the first round.

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  Aluminium 6061 / 7075Fast to cut, good for housings, brackets and heat sinks.
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  Stainless 303 / 304 / 17-4PHSlower, gummier chips, but needed for corrosion or food contact.
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  Titanium TC4 / InconelHigh heat and tool wear; reserve for aerospace or high-temperature parts.
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  Plastics POM / PEEKPEEK is expensive per kg and needs sharp tooling to avoid melting.

General tolerances around ±0.05 mm are routine on a 3-axis mill. Pushing to ±0.005 mm ( ±0.0002 in) changes the process: you need a temperature-stable shop, sharp tooling, slower feeds and more frequent in-process checks. The part may also need a finishing pass with a smaller stepover, which adds cycle time.

Surface finish follows the same logic. As-machined Ra 1.6–3.2 μm is the default from a good face mill or end mill. Ra 0.8–1.6 μm usually needs a finishing cutter and a slower pass. Ra 0.2–0.8 μm often means polishing or lapping after machining, which is manual work and hard to automate.

The practical rule: tighten only the features that touch something else. A bearing bore at ±0.005 mm makes sense. A cosmetic outer edge at ±0.005 mm usually does not. Mark critical dimensions on the drawing and leave the rest at general tolerance. Suppliers price what you call out, so a clean drawing is a cheaper drawing.

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  ±0.05 mmStandard milling and turning, no special climate control.
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  ±0.01 mmNeeds sharp tooling and a check pass; common on mating bores.
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  ±0.005 mmGrinding or fine boring may be required; add inspection time.

On a run of 1 to 50 parts, setup is the biggest single cost. Programming, workholding and first-article inspection can take two to four hours before the first good part comes off the machine. A 5-axis part may need a custom fixture and a probe routine. That fixed cost is spread across the batch, so the unit price falls fast as quantity rises.

Geometry decides how many setups are needed. A part with features on five faces may need two or three orientations on a 3-axis machine, each with its own fixture and re-datum. On a simultaneous 5-axis center, the same part can often be cut in one setup, which removes re-fixturing error and saves hours on small batches.

Thin walls and deep pockets are the two geometry traps. A wall under 1 mm deflects under cutting force, so the shop has to take light passes. A pocket deeper than three times the tool diameter needs a long, slender cutter that cannot run at full speed. Both cases add cycle time without adding a single new feature.

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  Fewer setupsDesign so most features are reachable from one or two directions.
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  Wall thicknessKeep walls above 1 mm where the part allows it.
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  Pocket depthStay under 3× tool diameter to avoid long, slow cutters.

Quantity changes the pricing model. A single prototype is priced on engineering and setup. A 10,000-part run is priced on cycle time, tool life and material buying power. Most shops have a break point where the quote switches from job-shop math to production math. Ask where that break point sits before you commit to a volume.

Finishing is quoted per batch for most processes. Anodizing, electroless nickel, zinc plating and powder coating all have minimum batch charges, so the per-part cost drops only when the batch is full. If you need three colors of anodize, expect three batch charges. Laser marking is usually fast, but minimum character height is 1.5 mm, so tiny logos may not be readable.

Inspection is the last line that surprises buyers. A standard job gets a first-article check and a final visual pass. A regulated job may need 100% inspection with dimensional reports, material certificates and traceability. That is real labor. If your industry requires it, say so up front so the quote includes it rather than adding it later.

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  Prototype volumeSetup and programming dominate; material is a small share.
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  Mid volume 100–1,000Cycle time and fixture amortization dominate.
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  High volume 10,000+Tool life, material contracts and automation dominate.

Certifications tell you which markets a shop can serve. ISO 9001:2015 covers general quality management. IATF 16949:2016 is required for automotive work. ISO 13485:2016 applies to medical devices. ISO 27001:2022 covers information security, which matters if your drawings are confidential. Ask for the certificate scope, not just the logo.

Machine list matters for part size. A shop with a 4,000 mm maximum processing size can handle long frames and rails. A shop limited to a 500 × 500 × 450 mm travel cannot. For parts with features on many faces, count simultaneous 5-axis centers and mill-turn centers, because those reduce setups and improve position accuracy between features.

Quality process matters more than a single tolerance number. Ask how in-process checks are done, how tool wear is tracked and what happens when a dimension drifts. A shop that inspects only at the end will find problems late. A shop that checks during the run catches drift before it becomes scrap.

Confidentiality is a practical issue for new products. Uploads should be secure, and an NDA should be available on request. If you are sending production drawings for an unreleased product, confirm the NDA before the files move, not after.

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  Certificate scopeConfirm the standard covers the process and site doing your work.
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  Size envelopeMatch the machine travel to your largest part dimension.
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  In-process inspectionAsk how drift is caught before the final check.
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  NDA timingSign before files are shared, not after the quote.