Common Brass Alloys used in CNC Machining

Written By Ryan Cudo

Introduction

Brass, a versatile alloy composed primarily of copper and zinc, is valued for its excellent combination of strength, corrosion resistance, and workability. Different types of brass alloys are created by varying the proportions of copper and zinc, as well as adding other elements such as lead, tin, and silicon. Among the various brass alloys available, Brass 260, 272, 360, 385, 464, 485, and 693 are some of the most commonly used due to their unique properties and applications.

Brass 260: Cartridge Brass

Composition:

  • Copper: 70%

  • Zinc: 30%

PhysicalProperties (H02):

  • Rockwell 70 HRB Hardness

  • Yield/Ultimate tensile strength of 52/62 ksi

  • Shear Strength 40 ksi

  • Shear Modulus 5800 ksi

  • Elasticity Modulus 16,000 ksi

Applications:

  • Ammunition casings

  • Plumbing fittings

  • Electrical components.

Brass 260 (C26000), or cartridge brass, is highly ductile, meaning it can be easily shaped or formed into various shapes. It also offers good strength and excellent cold workability, making it suitable for a wide range of applications.

Brass 272: Yellow Brass

Composition:

  • Copper: 65%

  • Zinc: 35%

Physical Properties (H02):

  • Rockwell 67 HRB Hardness

  • Yield/Ultimate tensile strength of 26/61 ksi

  • Shear Strength 37 ksi

  • Shear Modulus 5800 ksi

  • Elasticity Modulus 15,00 ksi

Applications:

  • Heat exchangers

  • Fasteners

  • Electrical Components

  • Musical instruments

  • Decorative Hardware

  • Plumbing fixtures.

Brass 272 (C27200), or yellow brass, is known for its good formability, machinability, and corrosion resistance, making it suitable for a variety of applications. Brass 272 is similar to Brass 260 but is slightly more formable, machinable, and resistant to corrosion due to its higher zinc content.

Brass 360: Free-Machining Brass

  • Copper: 61.5%

  • Zinc: 35.5%

  • Lead: 3%

Physical Properties (H02):

  • Rockwell 78 HRB Hardness

  • Yield/Ultimate tensile strength of 17/52 ksi

  • Shear Strength 32 ksi

  • Shear Modulus 5370 ksi

  • Elasticity Modulus 14,100 ksi

Applications:

  • Gears

  • Fittings

  • Valves

  • Precision parts.

Brass 360 (C36000) is the most common brass used in machining. The addition of lead improves the alloy's machinability, making it easier to cut and shape into intricate parts. The lead content, however, may limit its use in certain applications, such as those involving contact with drinking water, as lead can be harmful if ingested.

Brass 385: Architectural Brass

  • Copper: 57%

  • Zinc: 40%

  • Lead: 3%

Physical Properties (H02):

  • Rockwell 80 HRB Hardness

  • Yield/Ultimate tensile strength of 18/54 ksi

  • Shear Strength 33 ksi

  • Shear Modulus 5370 ksi

  • Elasticity Modulus 14,100 ksi

Applications:

  • Architectural elements

  • Decorative pieces

  • Sculptures

Brass 385 (C38500), or architectural brass, is known for its good corrosion resistance and ability to be polished to a beautiful finish, making it ideal for decorative applications. This alloy is similar to Brass 360, but is slightly more corrosion resistant due to higher zinc content. This alloy is typically used in decorative applications.

Brass 464: Naval Brass

Composition:

  • Copper: 60.5%

  • Zinc: 38.5%

  • Tin: 1%

Physical Properties (H02):

  • Rockwell 82 HRB Hardness

  • Yield/Ultimate tensile strength of 53/75 ksi

  • Shear Strength 44 ksi

  • Shear Modulus 4660 ksi

  • Elasticity Modulus 14,500 ksi

Applications:

  • Marine Hardware

  • Pumps

  • Fasteners

  • Bushings

  • Fittings that require high Corrosion Resistance

Brass 464 (C46400), or naval brass, takes the stage when corrosion resistance is paramount. This brass alloy is renowned for its excellent corrosion resistance, particularly in seawater.

Brass 485: Free-Machining Naval Brass

Composition:

  • Copper: 60.5%

  • Zinc: 36.75%

  • Tin: 1%

  • Lead: 1.75%

Physical Properties (H02):

  • Rockwell 82 HRB Hardness

  • Yield/Ultimate tensile strength of 53/75 ksi

  • Shear Strength 40ksi

  • Shear Modulus 5660 ksi

  • Elasticity Modulus 14,500 ksi

Applications:

  • Machined Marine parts

  • Fasteners

  • Bushings

Brass 485 (C48500), is a type of brass alloy that is similar to Naval Brass (Brass 464) but with added lead for improved machinability. However, like other leaded brass alloys, Brass 485 should be used with caution in applications involving drinking water or food contact, as lead can be harmful if ingested.

Brass 693: Silicon Brass

Composition:

  • Copper: 75%

  • Zinc: 21.9%

  • Silicon: 3%

  • Phosphorus: 0.1%

Physical Properties (H02):

  • Rockwell 85 HRB Hardness

  • Yield/Ultimate tensile strength of 49/87 ksi

  • Shear Strength 54 ksi

  • Shear Modulus 6000 ksi

  • Elasticity Modulus 16,000 ksi

Applications:

  • Valve stems

  • Pump components

  • High-stress fittings

  • High Strength Plumbing fittings

  • Bushings

Brass 693 (C69300), or Silicon brass, offers several advantages, including high strength, excellent corrosion resistance, and good machinability. These properties make it suitable for use in high-stress applications where durability and resistance to corrosion are essential.

Conclusion:

Understanding the properties and applications of these common brass alloys can help you select the right material for your project. Whether you need a brass alloy that offers superior machinability, corrosion resistance, or strength, there's a brass alloy that fits the bill. With its timeless appeal and versatility, brass continues to be a go-to material for a wide range of applications across industries.


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Ryan Cudo
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