Free Cutting Brass

Free Cutting Brass

Leaded brasses, commonly referred to as free-cutting brasses, are designed to offer superior machinability, making them ideal for high-speed machining processes. The addition of lead in these alloys improves their machinability by creating a lubricating effect during cutting and reducing friction.

Composition:

  • Copper (Cu): Approximately 57-61%
  • Zinc (Zn): Approximately 35-39%
  • Lead (Pb): Approximately 2.5-3.5%
  • Other elements: May include small amounts of iron (Fe), tin (Sn), and aluminum (Al) to enhance specific properties.

Grades

ASTM B 455 / B 16 C 38500 / C 36000:

  • ASTM standards specifying the composition and mechanical properties for leaded brasses.

BS 2874 CZ-121Pb3 or CZ124:

  • British Standards specifying the requirements for free-cutting brass alloys.

IS319 Grade I/II/III:

  • Indian Standards specifying the composition and properties for different grades of leaded brass.

JIS 3250 H C3604 or C3602:

  • Japanese Industrial Standards specifying the requirements for free-cutting brass alloys.

EN CW614N / CW603N:

  • European standards specifying the composition and properties for free-cutting brass alloys.

Properties:

  1. Corrosion Resistance:
    • Good general corrosion resistance, suitable for many industrial and commercial applications.
    • Moderate resistance to dezincification, not typically suitable for highly aggressive environments.

  2. Mechanical Properties:
    • Tensile Strength: Typically around 350-450 MPa.
    • Yield Strength: Approximately 100-250 MPa.
    • Elongation: Generally around 20-30%, indicating good ductility.
    • Hardness: Moderate hardness, with a typical Brinell hardness number (HB) of around 80-120.

  3. Machinability:
    • Excellent machinability due to the presence of lead, making it ideal for high-speed machining and turning operations.
    • Often used in automatic screw machines and other machining equipment.

  4. Thermal and Electrical Conductivity:
    • Good thermal conductivity, suitable for heat exchange applications.
    • Moderate electrical conductivity, sufficient for many industrial uses but lower than pure copper.

Applications:

  • Machined Components: Extensively used in the production of precision machined components, such as fittings, connectors, valves, and fasteners.

  • Automotive and Aerospace: Employed in automotive and aerospace industries for components requiring precise machining and reliable performance.

  • Electrical and Plumbing Systems: Used in electrical connectors and plumbing fittings due to its good machinability and adequate corrosion resistance.

  • Industrial Equipment: Suitable for various industrial equipment parts, including gears, bearings, and bushings, where precise machining is required.

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