Free Cutting Brass: Material Grades and Chemical Composition
Free Cutting Brass, also known as Free Machining Brass, is a type of brass alloy specifically designed to offer superior machinability. It is widely used in high-speed precision machining applications, thanks to the addition of lead (Pb), which acts as a lubricant and reduces friction. This improves the cutting process, extends tool life, and enhances the surface finish of machined components.
In this blog, we will explore the material grades, chemical composition, and properties of Free Cutting Brass, highlighting its industrial applications and advantages.
What is Free Cutting Brass?
Free Cutting Brass is a copper-zinc-lead alloy with excellent mechanical properties and corrosion resistance. It is commonly used for precision components in industries such as automotive, electrical, plumbing, and industrial hardware. The high machinability of free cutting brass makes it the preferred material for applications requiring intricate machining, threading, and drilling.
Material Grades of Free Cutting Brass
There are several material grades of free cutting brass, each with specific chemical compositions and mechanical properties. Below are the most commonly used grades:
| Standard | Material Grade | Equivalent Grades |
|---|---|---|
| JIS (Japan) | C3604, C3603 | CuZn39Pb3, CW603N |
| UNS (USA) | C36000, C38500 | CuZn39Pb2, CuZn39Pb3 |
| EN (Europe) | CW617N, CW614N | CuZn40Pb2, CuZn39Pb2 |
| ISO | CuZn39Pb3 | CZ121 |
| DIN (Germany) | 2.0401, 2.0380 | CuZn39Pb3, CuZn36Pb2 |
| BS (UK) | CZ121, CZ124 | CuZn39Pb3, CuZn40Pb2 |
| ASTM (USA) | B16, B455 | C36000, C38500 |
Chemical Composition of Free Cutting Brass
The chemical composition of free cutting brass varies slightly based on the material grade. Below is the general composition range:
| Element | C3604 (%) | C3603 (%) | C36000 (%) | CZ121 (%) | C38500 (%) | CW617N (%) |
|---|---|---|---|---|---|---|
| Copper (Cu) | 57.0 - 61.0 | 58.0 - 61.0 | 60.0 - 63.0 | 57.0 - 59.0 | 55.0 - 59.0 | 57.0 - 59.0 |
| Zinc (Zn) | Balance | Balance | Balance | Balance | Balance | Balance |
| Lead (Pb) | 1.8 - 3.7 | 1.5 - 3.5 | 2.5 - 3.7 | 2.5 - 3.5 | 1.5 - 3.0 | 1.8 - 3.0 |
| Iron (Fe) | ≤ 0.5 | ≤ 0.5 | ≤ 0.5 | ≤ 0.3 | ≤ 0.35 | ≤ 0.3 |
| Nickel (Ni) | ≤ 0.3 | ≤ 0.3 | ≤ 0.3 | ≤ 0.2 | ≤ 0.2 | ≤ 0.2 |
| Others | ≤ 0.3 | ≤ 0.3 | ≤ 0.3 | ≤ 0.2 | ≤ 0.3 | ≤ 0.2 |
Key Features of Free Cutting Brass Composition:
- High copper content (55-63%) ensures good corrosion resistance and electrical conductivity.
- Lead (1.5-3.7%) improves machinability and ensures smooth cutting.
- Iron and nickel are kept low to maintain workability and strength.
- Zinc (balance) provides strength and hardness while keeping the material cost-effective.
Properties of Free Cutting Brass
Free Cutting Brass offers a unique combination of mechanical properties, making it ideal for precision machining applications.
| Property | Typical Value |
|---|---|
| Density | 8.4 - 8.7 g/cm³ |
| Melting Point | 890 - 920°C |
| Tensile Strength | 330 - 550 MPa |
| Yield Strength | 100 - 300 MPa |
| Elongation | 10 - 30% |
| Hardness (HB) | 80 - 130 |
| Electrical Conductivity | 23 - 28% IACS |
Why Choose Free Cutting Brass?
- ✅ Superior machinability – Ideal for high-speed machining operations
- ✅ Good corrosion resistance – Suitable for marine, plumbing, and industrial applications
- ✅ High strength and wear resistance – Ensures durability and reliability
- ✅ Excellent electrical conductivity – Used in electrical connectors and components
- ✅ Cost-effective material – Reduces tool wear and increases efficiency
Free Cutting Brass is a highly versatile and machinable alloy that meets the demands of various industries. Its chemical composition, superior machinability, and international standards compliance make it the perfect choice for precision engineering and industrial applications.
At Lexus Metal Alloys, we manufacture high-quality free cutting brass in different grades, including C3604, C3603, C36000, CZ121, C38500, and CW617N. Our brass products are engineered for precision, durability, and performance in industrial applications worldwide.
👉 Looking for premium free cutting brass? Contact us today to discuss your requirements!