GRADE GUIDE · CUZN39PB3
CuZn39Pb3 (CW614N / C38500) is free-machining brass — about 3% lead dispersed through a 58/39 copper-zinc base, making it the fastest-machining common metal there is. Fittings, valve bodies, inserts and turned precision parts are its home ground.
Also listed as: CW614N · C38500 · Ms58 (old DIN) · 2.0401
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The lead does one job: it breaks chips. On a CNC lathe or screw machine, CuZn39Pb3 cuts at speeds no steel approaches, with mirror finishes and minimal tool wear — machining-cost savings that usually outweigh the metal price. It is the material CNC workshops feed by the tonne for connectors, bushes, gas fittings and instrument bodies.
The same lead rules it out of forming — bend it and it cracks — and out of drinking-water contact under modern low-lead rules, where dezincification-resistant or lead-free grades take over. Off-cuts here are rod and hexagon bar ends from turning shops: short certified lengths that suit exactly the small-batch machining that generates them.
Lead particles break the chip and lubricate the cut, so it machines several times faster than steel with excellent finish and long tool life. For turned brass parts there is no cheaper metal per finished component.
Increasingly no — low-lead regulations exclude 3%-lead brass from potable contact in most modern specifications. Compliant plumbing parts use DZR or lead-free brasses; this grade serves gas, pneumatic and mechanical duty.
Avoid it — the lead that helps machining causes cracking under cold deformation. Parts needing forming belong in CuZn37; parts needing turning belong here.