CNC Brass Machining Parts Service: What Drives the Price

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  Key takeaways
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  What moves the price for CNC brass machining parts service
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  Brass alloy choice sets the material cost
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  Tolerance and finish are the second cost block
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  Quantity, setup and how the quote is built
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  Geometry and features that raise the price
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  Comparing suppliers, not just numbers
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  Step by step: getting a comparable brass quote

Brass is not one material. C36000 free-machining brass is the default for turned parts because the chips break short and tools last. C27400 and C28000 are stronger and more corrosion resistant, but they cut slower and the bar stock costs more. Beryllium copper sits at the top: excellent conductivity and spring properties, and a price to match.

The practical question is whether the part needs the extra property. A connector body that only carries current and holds a thread rarely needs beryllium copper. A spring contact or a high-cycle bushing often does. If the drawing says brass without a grade, ask which one the shop plans to buy, because that single line changes the quote more than almost anything else.

Bar stock size matters too. A part that needs a Ø60 mm bar when a Ø40 mm bar would do pays for metal that becomes chips. On a 10,000-part run that difference is real money. When you send a drawing for quotation, the shop should tell you which stock size it assumed.

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  C36000Best machinability, lowest cost per part, the default for turned brass.
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  C27400 / C28000Higher strength and corrosion resistance, slower cutting.
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  Beryllium copperConductivity and spring properties, highest material cost.

Tolerance is where drawings quietly get expensive. A ±0.05 mm callout on a brass part is routine on a 3-axis mill. Tightening the same feature to ±0.005 mm means slower passes, temperature awareness and more frequent checks. Our floor holds ±0.005 mm, but we charge for the time it takes to hold it.

The common mistake is applying one tolerance block to the whole drawing. Shaft diameters that mate with a bearing need the tight callout. A clearance hole for an M4 screw does not. Marking tight tolerance only where it functions usually cuts a brass quote by more than a change of supplier would.

Finish works the same way. Ra 1.6–3.2 μm as machined is standard. Ra 0.8–1.6 μm needs a finishing pass. Ra 0.2–0.8 μm is a different operation with different fixturing. Specify the fine finish on sealing faces and sliding surfaces, and leave the rest as machined.

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  Tight where it matesBearings, seals and press fits earn the ±0.005 mm callout.
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  Loose where it clearsFastener clearance holes rarely need better than ±0.1 mm.
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  Finish on functionRa 0.8–1.6 μm on contact faces only.

Every brass job carries a fixed cost: programming, fixtures, first-article checks. On a ten-part order that fixed cost can be most of the invoice. On a 10,000-part order it is a rounding error. This is why the same drawing can come back at very different unit prices from the same shop, depending only on the batch size you ask for.

The trick for small programs is not to hide the setup but to reuse it. If you know a design will go through three revisions, ask the shop to quote the run and the rework separately. Some fixtures survive a revision. Some do not. Knowing which is which before you commit saves a second setup charge.

We run no minimum order quantity, from one prototype to 10,000+ part runs. That does not mean one part is cheap. It means you can buy one part, validate it, then buy the run without changing suppliers and paying setup twice.

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  Fixed costProgramming, fixturing and first-article inspection.
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  Variable costMaterial, cycle time and tool wear per part.
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  Reuse setupAsk which fixtures survive a design revision.

A brass part with a simple turned profile is quick work. Add a deep small-diameter hole and cycle time jumps, because the drill needs pecking and the chip has to clear. Add fine threads below M2 and the risk of tap breakage rises, so the shop runs slower and inspects more. Add a thin wall under 0.8 mm and workholding becomes the problem, not cutting.

Internal cavities and cross-drilled passages are the other common cost jump. They often need a second or third operation on a different machine, which means a second setup and a second chance to lose position. A five-axis machine can reach some of these in one setup, but only if the part fits the work envelope.

If a design is still open, simplify before you quote. A slightly larger hole, a coarser thread or a thicker wall can cut the unit price without touching function. Ask the shop for a DFM note. We return quotation and free DFM analysis within 12 hours, and the DFM note often lists the two or three changes that matter.

Two quotes for the same brass part can differ for reasons that have nothing to do with margin. One shop may assume a Ø40 mm bar, the other a Ø60 mm bar. One may include a CMM report on every dimension, the other only on the critical ones. One may plan a 4-axis mill with two setups, the other a mill-turn center with one. The number alone tells you very little.

Certifications are a useful filter but not a price guarantee. ISO 9001:2015 covers general quality management. IATF 16949:2016 matters for automotive work. ISO 13485:2016 matters for medical devices. ISO 27001:2022 covers information security, which is relevant if your drawings are sensitive. A shop without the certification your industry requires will either decline the job or add cost to meet it.

For brass specifically, ask how the shop handles chip control and tool wear on long runs. Brass chips are abrasive and they carry heat away. A shop that tracks tool life will hold dimensions across a 10,000-part run. A shop that runs tools to failure will not.

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  AssumptionsStock size, setup count and inspection level should be stated.
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  CertificationsMatch the certificate to your industry, not to the brochure.
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  Tool lifeAsk how dimensions are held across a long run.