Brass reference / Leaded brass
C360 free-cutting brass
The benchmark every other metal is rated against for machinability, and the default for turned brass parts.
Also known as Free machining brass, Alloy 360, Screw machine brass. Published typical values for the alloy, never a promise from a shop.
Composition
| Element | Nominal weight % |
|---|---|
| Copper | 60.0 to 63.0 |
| Lead | 2.5 to 3.7 |
| Iron | 0.35 max |
| Zinc | remainder |
Properties
- UNSC36000
- EN equivalentCuZn36Pb3 / CW603N
- Hardness60 to 80 HRB
- Density8.49 g/cm3
- Typical tolerance±0.01 mm routine on turned features
- Common formsRound, hex and square bar, extruded shapes
What it is for, and what it is not
Specify it for
- Turned parts made from bar in any volume
- Threaded fittings, adapters and connector bodies
- Industrial and electrical parts in dry service
- Anything where cycle time drives the price
Do not specify it for
- Wetted potable water parts in the US, it is over ten times the NSF/ANSI 372 lead limit
- Hot water and seawater, where it dezincifies
- Electrical equipment sold in the EU after the RoHS 6(c) exemption ends
What a buyer should know
The lead does not alloy with the copper and zinc. It sits in the structure as discrete soft particles that break the chip and lubricate the cutting edge, which is the entire reason this alloy cuts the way it does. Everything good and everything problematic about C360 traces back to those particles.
Nominal lead is 2.5 to 3.7 percent, which is above the 0.25 percent weighted average limit that NSF/ANSI 372 sets for wetted potable water surfaces. See NSF/ANSI 61 and 372 and RoHS exemption 6(c).
Dezincification resistance is poor, so this alloy is the wrong choice sitting in hot water or seawater regardless of how well it machines. See dezincification and the grades that resist it.
Closest alternatives
| Alloy | Lead % | Mach. | DZR | Why you might switch |
|---|---|---|---|---|
| C385 architectural bronzeC38500 | 2.5 to 3.5 | 90 | Poor | A brass despite the name, supplied mainly as extruded shapes and the default where the part is seen. |
| C377 forging brassC37700 | 1.5 to 2.5 | 80 | Poor | Hot forged to a near net shape then machined only where a sealing face or thread requires it. |
| C69300 silicon brassC69300 | under 0.09 | 80 | High | The usual lead-free answer for potable water, roughly twice as strong as C360 and highly dezincification resistant. |
Need a shop that runs C360?
Send the drawing and we match it with up to 3 shops that turn brass. Free for buyers, reply within 24 business hours.