Brass CZ121

Your guide to Brass CZ121



100% rating for machinability

The European brass grade of choice for many machined components

High tensile strength

Brass CZ121 has exceptional machinability and high tensile strength plus good corrosion resistance and conductivity.

This guide will take you through the main attributes, common applications, notes for designers and suitable finishing and treatments, as well as UK stock sizes and property tables. Don't forget to bookmark the page so you can refer back later.

If you are interested in CZ121 brass machined parts, please scroll to the bottom of the page for more information about our service and to request a quote.

Brass CZ121: Properties, Applications and Design Considerations


What is CZ121?
CZ121 (CW614N) is an alpha/beta (duplex) brass alloy containing 37-39% zinc. These duplex alloys have restricted ductility being harder and have a higher tensile strength than alpha alloys which contain less than 37% zinc.

CZ121 typically contains 3% lead, giving great high speed, free machining characteristics (machinability rating of 90-100, the highest of any copper alloy).

As a result CZ121/CW614N is the European brass grade of choice for many machined components.


CZ121 Machinability


Brasses and in particular CZ121 are given a 100% rating for machinability and as such are regarded as the “standard” against which all other materials' machinability is judged and rated.

The finely dispersed 3% Lead content of CZ121 results in superior chip breaking and thus assists with swarf management through the machining process. Good surface finishes are also straightforward to achieve. This is due to the Lead being spread throughout the microstructure where it remains insoluble. The Lead also lubricates machining operations. Therefore although the alloy grade is not suited or recommended for cold working, the lead content results in successful thread rolling and knurling.

Like aluminium, brass can be “sticky” to the tool and flood coolant is recommended.


Similar or obsolete designation and trade names 

You may also see CZ121 referred to as:

  • CW614N
  • C36000
  • CA121M
  • BS2874
  • 2.0401
  • NF A51-105
  • The following designations may not be direct equivalent:
    • UNS C38500
    • CuZn39Pb3
    • CuZn40Pb3 (FR)
Industry Examples: Electrical | Electronics | Fluid power | Scientific and instrumentation | Machinery builders | Architecture | Plumbing | Low level security
Typical Components & Applications: Bushes | Bearings | Pins | Hinges | Locks | Trims | Simple and intricate fastenings | Architectural extrusions | Valves | Fittings | Manifold blocks | Tools | Pneumatics & hydraulics | Electrical connectors and terminals | Appliance parts | Watch components | Building products

Main Attributes:
  • Excellent machinability
  • High tensile strength
  • Good corrosion resistance
  • Easily soldered or brazed
  • Good conductivity
  • Good spark resistance
  • Toughness at all temperatures - excellent for hot working (between 630 - 730°C)
  • Low magnetic permeability

Note For Designers:

Like many yellow metals brass prices do fluctuate more than other ferrous and non-ferrous materials. This means that quotes are generally only valid for around one week.

  • The CZ121 can be annealed or solution treated by heating to 430 - 600°C and then being rapidly cooled.
  • When hot worked between 630 - 730°C, CZ121 is excellent in fabricating components.
  • CZ121’s brazing and soldering qualities are very good and much more preferable to welding.

Finishing & Treatments:

The following gives a brief explanation of what plating processes can be applied to CZ121 and the reasons for doing so:

  • Electroless Nickel Plating - increases the surface hardness, wear resistance, corrosion protection and improves solderability for electronic applications.
  • Black Nickel Plating - to create a non reflective surface
  • Nickel Plating - ductile, semi-bright finis used for decorative purposes, wear and corrosion resistance or to aid soldering. Nickel is a common under/barrier coat as the preparation for other metal plating deposits.
  • Copper Plating - again a common under/barrier coat as the preparation for other metal plating deposits.
  • Silver Plating - improves electrical conductivity, lowers resistance, offers resistance to most common acids and is also used to prevent galling on high load surface applications
  • Gold Plating - highly corrosive resistant, improves wear and contact resistance 
  • See our Finishing Processes page for further information on services that we can facilitate. 

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Further Reading & Resources

Copper Alliance


Brass CZ121 Machined Parts


Penta Precision provides the following CZ121 brass machining services: 
  • CNC milling
  • CNC turning
  • Prototypes and batch runs
  • Insert installation
  • Part marking
  • Manual milling
  • Manual turning
  • Machining design advice
  • Design for manufacture service

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