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Machinable Brass Grades: Why C36000 Sets the 100% Benchmark

Brass alloy selection for CNC turning and milling · Boyang Hardware, Zhongshan, Guangdong, China

Direct answer C36000 free-cutting brass (also sold as C360 or HPb59-1 equivalents) is the most machinable brass in common use and carries the industry reference rating of 100% machinability. Its roughly 3% lead content breaks chips cleanly and lets tools run fast with excellent finish. Other frequent choices: C3604/C3605 (Japanese equivalents, ~90%), C485 (high-strength leaded naval brass), C464 naval brass (~30%, corrosion-duty parts) and C260 cartridge brass (~30%, best for deep drawing and forming, harder to turn). Choose C36000 for screw-machine parts; move to unleaded or naval grades only when corrosion or lead regulations require it.

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Brass grade comparison for CNC machining

Table 1 — Commonly machined brass alloys. Machinability ratings follow the standard copper-alloy scale where C36000 = 100. Ratings are industry guidance, not guarantees of tool life on a specific geometry.
Grade (UNS) Common name Nominal composition Machinability rating Best used for
C36000 Free-cutting brass Cu 61.5%, Zn 35.5%, Pb 3% 100 Screw-machine parts, fittings, valves, inserts — the default choice
C3604 / C3605 Japanese free-cutting brass (JIS) Cu 57–61%, Pb 1.7–3.5%, bal. Zn ~90–100 Asian-supply equivalents of C36000; widely stocked in China
C48500 High-strength leaded naval brass Cu 60%, Zn 39.25%, Pb 0.75%, Sn 0.75% ~70–80 Marine shafts, corrosion-duty hardware needing more strength
C46400 Naval brass (unleaded) Cu 60%, Zn 39.25%, Sn 0.75% ~30 Marine and saltwater-contact parts where lead content must be zero
C26000 Cartridge brass Cu 70%, Zn 30% ~30 Deep-drawn, stamped and formed parts; machining is slower with gummy chips
C11000 copper ETP copper (for comparison) Cu 99.9% ~20 Electrical and thermal parts — see copper CNC machined parts

What lead actually does in the cut

Lead is nearly insoluble in the copper-zinc matrix, so it solidifies as tiny globules between the grains. During cutting these globules do two jobs at once: they embrittle the chip locally so it snaps into short pieces instead of winding around the tool, and they smear over the tool face as a solid lubricant that cuts friction and built-up edge. The result is that C36000 can be turned several times faster than the same geometry in C26000 cartridge brass, with a bright as-machined finish that often needs no secondary polishing.

At Boyang Hardware, brass is machined on the same CNC turning and 3/4/5-axis milling equipment used for aluminium and stainless steel — 54 machine tools in total. Typical tolerances are ±0.01 mm turned, with 0.001 mm available on critical features via our grinding or wire EDM operations, and 100% CMM inspection before every shipment.

Choosing a grade by application

Table 2 — Decision guide. Send the drawing and application notes; final grade selection is confirmed at quotation in 1–2 working days.
If your part is… Recommended grade Reason
A valve, fitting, connector or threaded insert C36000 Maximum cutting speed, clean threads, lowest unit cost
A decorative or plated component C36000 or C3604 Fine as-machined finish takes plating well — see plating options
In contact with seawater or marine atmospheres C46400 / C48500 Tin addition suppresses dezincification
A potable-water or food-contact part for regulated markets Unleaded / low-lead alternatives Lead-leaching restrictions; reviewed case by case
A high-volume simple bracket or blank in brass-family metal C26000 (formed then machined) Excellent cold formability; machining only where needed — see process break-even analysis
Honest limits: C36000 is not a structural or high-temperature alloy — its strength and creep performance are modest, and leaded brass is restricted in many drinking-water, food and RoHS-adjacent applications, so regulatory fit must be checked on your side before the drawing is released. Machinability ratings are comparative, not a tool-life promise: deep small-diameter drilling and very thin walls still demand reduced parameters regardless of alloy. We do not supply a "100% machinable on any design" guarantee — complex geometries in C36000 still cost more than simple ones.

FAQs

What is the closest Chinese stock equivalent to C36000?

HPb59-1 and the JIS C3604/C3605 families are the widely stocked equivalents in Chinese mills. Composition windows differ slightly, so the material certificate supplied with the shipment states the actual heat analysis — see materials guide.

Does brass need any finish after machining?

Often no: as-machined C36000 has a bright finish that resists tarnish reasonably well indoors. Where appearance or corrosion life matters, plating (nickel, chrome) or lacquer is arranged and certified.

How does machining cost compare between C36000 and C26000?

For pure machining, C36000 is cheaper per part despite similar bar-stock pricing, because cutting speeds are much higher and tool wear lower. C26000 earns its cost back only when the part is mostly formed rather than cut.