The most machinable metal in routine use — C360 sets the 100% benchmark by which all other machinability ratings are measured. The 2.5–3.7% lead content is what enables this: lead globules in the brass matrix act as internal lubricant and chip-breaker, allowing extremely fast cutting speeds, long tool life, and excellent surface finish straight off the tool. The trade-off is drinking-water restrictions and EU/CA regulatory constraints — covered below.
C360 is the default choice for high-volume turned brass parts — fittings, valves, fasteners, electrical terminals, decorative hardware — because the economics are overwhelming. Cutting speeds are 3–4× equivalent aluminum, 6–8× stainless steel. Tool life is exceptional. Surface finishes of Ra 0.4 μm come straight off the turret without secondary operations. For a Swiss-type machine running brass fittings, cycle times are typically limited by tool-change robotics, not cutting speed.
But the regulatory landscape has shifted significantly since 2014. The US Safe Drinking Water Act (SDWA) now limits lead content in "wetted surfaces" of plumbing products to 0.25%, effectively banning C360 from drinking-water fittings. The EU RoHS and REACH have similar restrictions for specific applications. For compliance with these regulations, C693, C87850, or other lead-free brass alloys are required — these machine roughly 60–70% as well as C360 and cost 10–20% more, but are the only legal option for potable water.
Specifying C360 for a plumbing fitting that will contact drinking water in the US or EU is a regulatory violation. Your customer cannot legally sell it. Before ordering C360 for anything water-related, confirm the end-use with your design team. If there's any chance the fitting will touch potable water — even once — specify lead-free brass (C693 / C87850 / C46500) instead.
| Application | C360 allowed? | Alternative if no |
|---|---|---|
| Drinking water fittings (US) | NO — SDWA 0.25% Pb limit on wetted | C693, C87850, C46500 (lead-free) |
| Drinking water fittings (EU) | NO — DWD 2020/2184 limits | Same as US |
| Industrial fluid handling (non-potable) | Yes | — |
| Electrical connectors / terminals | Yes | — |
| Decorative / architectural | Yes | — |
| Firearms components | Yes (non-exposed) | — |
| Musical instruments | Yes | — |
| Medical devices (EU MDR) | Depends — check REACH SVHC | Lead-free or stainless |
| Toys / children's products | NO — CPSIA 100 ppm Pb | Lead-free |
| Element | Min % | Max % | Role |
|---|---|---|---|
| Copper (Cu) | 60.0 | 63.0 | Matrix, corrosion resistance |
| Lead (Pb) | 2.5 | 3.7 | Free-machining agent |
| Zinc (Zn) | balance (~36%) | Strength, cost | |
| Iron (Fe) | — | 0.35 | Impurity |
| Property | Value | Notes |
|---|---|---|
| Ultimate tensile strength | 385 MPa | ~56,000 psi |
| Yield strength (0.5% ext) | 310 MPa | — |
| Elongation at break | 25% | Half-hard |
| Hardness | 78 HRB | — |
| Modulus of elasticity | 97 GPa | — |
| Density | 8.50 g/cm³ | — |
| Electrical conductivity | 26% IACS | Lower than pure copper, still usable |
| Thermal conductivity | 115 W/m·K | — |
| Machinability index | 100 | ISO benchmark |
| Color | Yellow-gold, polishes to bright finish | |
| Dezincification | Susceptible in aggressive water — consider DZR alloys (CW602N / C35330) if this matters | |
C360 cuts easily with any tooling material. The practical limits are usually machine capability and chip handling, not cutting conditions. Use neutral to slightly positive rake, good chip breakers, and adequate coolant to manage the fine lead-containing chips (which are a health hazard — collect separately).
| Operation | Surface speed (m/min) | Feed per tooth (mm) | Tool |
|---|---|---|---|
| Turning (rough) | 180–400 | 0.15–0.40/rev | Uncoated carbide, chip breaker |
| Turning (finish) | 250–600 | 0.05–0.15/rev | Sharp carbide or cermet |
| Face milling | 200–450 | 0.15–0.30 | Polished PCD or uncoated carbide |
| End milling | 150–350 | 0.05–0.20 | 2–3 flute carbide |
| Drilling | 60–120 | 0.10–0.25/rev | Standard HSS or carbide |
| Tapping | 12–25 | — | Straight-flute HSS |
Non-potable fluid handling. Hydraulic, pneumatic, gas systems. High-volume Swiss-turned production.
Plug pins, screw terminals, battery contacts. Good conductivity + machinability for high-volume production.
Door handles, lock cylinders, escutcheons, hinges. Takes decorative finishes (polished, satin, patinated, lacquered).
Brass instrument valves, tuning slides, mouthpiece receivers. Acoustic and traditional aesthetic drivers.
Non-load-bearing parts, decorative, some triggers and safeties. Bright, stable, machinable.
Gears, arbors, small precision parts requiring the best attainable surface finish and dimensional control.
| Alloy | Pb% | Machinability | Primary use |
|---|---|---|---|
| C360 (free-machining) | 2.5–3.7 | 100 | High-volume turned parts (non-potable) |
| C385 (architectural bronze) | 2.5–3.5 | 90 | Extruded sections, architectural |
| C260 (cartridge brass) | <0.07 | 30 | Deep drawing, cartridge cases |
| C464 (naval brass) | <0.1 | 30 | Marine hardware, saltwater |
| C693 / C87850 (lead-free) | <0.09 | 65–70 | Drinking water fittings |
| C46500 (naval lead-free) | <0.1 | 50 | Marine potable water |
| CW602N / C35330 (DZR) | 1.7–2.8 | 80 | Dezincification-resistant |
Lead content makes C360 unfit for drinking water, toys, food contact, and many medical applications. Your regulatory risk falls on whoever sells the finished product, but supply-chain contamination of a "lead-free" part with C360 can trigger recalls. Don't substitute without engineering approval.
EN 12164 CW614N is the European direct equivalent to C360. Your EU customer's drawing may specify CW614N or CZ121; treat as identical for machining purposes.
C360 is susceptible to dezincification in slightly acidic or high-chloride water, leaving a porous copper structure. For fluid handling in these conditions, specify dezincification-resistant (DZR) brass like CW602N (C35330).
C360 chips are small and dense. Production runs generate significant swarf weight — we include reclaim value in production quotes above 100 kg total chip mass. Lead-containing swarf requires controlled handling and disposal per local regulation.
Bare C360 tarnishes over months in humid air. For decorative parts, specify clear lacquer (Incralac is common) or electroplated protection. Bright-dip acid cleaning restores mirror finish but does nothing for long-term oxidation.
Bar-fed Swiss-type lathes with sub-spindle. Typical unit cost reduction of 40–60% vs. conventional turning for qualifying geometries. Quote includes process plan and setup costs broken out.