CZ121, CW614N and C36000 are three names for closely related free-machining brasses. Each is a copper-zinc alloy with roughly 3% lead, which makes the chips break short and lets automatic lathes run fast.
They are not identical. Each comes from a different standard with its own composition limits, so put the exact grade and standard on your drawing rather than writing "brass" or "equivalent".
Where each name comes from
- CZ121 is the old British designation, from BS 2874 and related standards, for a leaded free-cutting brass. It is still widely used on drawings and in Indian mill catalogues.
- CW614N is the European designation under EN 12164 for rod, with the chemical name CuZn39Pb3. It replaced CZ121 in most European specifications.
- C36000 is the American UNS number for free-cutting brass, supplied to ASTM B16. It has slightly more copper and a lead range of roughly 2.5 to 3.7%.
Other grades you will see
Jamnagar suppliers work with several other brasses. The choice depends on whether the part is turned, forged or used with drinking water.
- CW617N (CuZn40Pb2) is the common forging brass for valve and fitting bodies.
- CW602N (CuZn36Pb2As) is a dezincification-resistant grade, explained in what DZR brass is.
- Low-lead and lead-free grades, often silicon or bismuth brasses, are used where drinking water rules apply.
- Lower-zinc brasses such as CuZn30 or CuZn37 are used where a part must be cold-formed or crimped.
How to choose between them
If your part is turned from bar and has no special rules, CW614N or C36000 is the usual default. Pick the one that matches your market's standards and your customer's drawings, so inspection and certificates line up.
If the part is forged, a forging brass such as CW617N works better, because it flows into the die at forging temperature. If the part bends, crimps or is pressed, a low-lead, higher-copper grade avoids cracking. If it touches drinking water, the rules in your market decide the grade, not machinability.
The risk with mixed scrap
Much Indian brass rod is made from recycled scrap. That is normal and can give excellent material. The risk is that poorly controlled melts drift outside the limits for lead, iron or tin, or pick up elements such as cadmium.
Ask for a mill test certificate with each lot of rod, and check that it states the standard and the measured composition. For critical parts, have an independent lab run a spectrometer check on a sample from your actual lot. The guide to reading a lab certificate shows what to look for.
If your part goes into drinking water systems, a 3% lead brass may not be allowed at all. Read what lead-free brass is and when it is required before you fix the grade.
Next step
Getting the alloy right on paper is easy. Getting the right alloy in every lot needs checks at the rod stage. We check documents and have lots tested before shipment. To set up material checks for your parts, book a free sourcing review.