Why brass is used for turned parts
Brass is an alloy of copper and zinc. Free-cutting brasses add a small amount of lead, which forms fine particles in the metal and makes chips break into short pieces. That is why leaded brass can be machined at high speed on automatic lathes with good tool life, fine threads and a clean surface. Brass also conducts electricity well, resists corrosion in most indoor environments and takes plating easily.
Common grades at a glance
| Grade | Standard | Nominal composition (%) | Machinability | Typical uses |
|---|---|---|---|---|
| CW614N (CuZn39Pb3) | EN 12164 | Cu 57.0–59.0, Pb 2.5–3.5, Zn balance | Excellent | Terminals, inserts, fasteners, general turned parts |
| CW603N (CuZn36Pb3) | EN 12164 | Cu 60.0–62.0, Pb 2.5–3.5, Zn balance | Excellent | Turned parts that also need some cold forming, such as crimping |
| C36000 | ASTM B16 | Cu 60.0–63.0, Pb 2.5–3.7, Zn balance | Excellent (the US machinability reference) | Free-cutting brass for the North American market |
| CW602N (CuZn36Pb2As) | EN 12164 | Cu 61.0–63.0, Pb 1.7–2.8, As 0.02–0.15, Zn balance | Good | Dezincification-resistant (DZR) fittings for water systems |
| CW617N (CuZn40Pb2) | EN 12164 / EN 12165 | Cu 57.0–59.0, Pb 1.6–2.5, Zn balance | Very good | Hot-stamped (forged) bodies that are then machined, such as valves |
Dezincification and DZR brass
In some waters, ordinary brass can lose zinc from its surface and leave behind a weak, porous copper layer. This is dezincification, and it can make fittings leak or fail over time. DZR (dezincification-resistant) brasses such as CW602N control the composition, with a small arsenic addition and a higher copper content, and are usually heat treated so the structure resists this attack.
- Use DZR brass for fittings in contact with potable or aggressive water.
- Free-cutting grades such as CW614N are fine for dry, indoor and electrical applications.
- Where drinking-water rules restrict lead, low-lead or lead-free brasses (for example CW511L or silicon brasses) are used instead; they machine differently and cost more.
How to choose
| If the part is… | Consider |
|---|---|
| An electrical terminal, insert or general turned part | CW614N / C36000 (best machinability) |
| Crimped, bent or flared after machining | CW603N (higher copper, more ductile) |
| A fitting in contact with water | CW602N DZR, or a low-lead grade where regulations require it |
| A forged body with machined features | CW617N |
| For a market with lead limits | Confirm the applicable rule first, then a compliant low-lead grade |
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