CDA 360 Brass C36000 Free machining Brass: The Gold Standard of Free-Cutting Alloys
CDA 360 / C36000 Brass composition:
| Element | Composition (Range / Typical) |
|---|---|
| Copper (Cu) | 60.0 – 63.0 % (nominal ~61.5%) |
| Zinc (Zn) | Balance (~35 – 37%) |
| Lead (Pb) | 2.5 – 3.0 % (nominal ~3%) |
| Iron (Fe) | ≤ 0.35 % |
| Residuals | ≤ 0.5 % |
When manufacturers talk about the king of machinability, they are often referring to CDA 360 Brass (also known as C36000 Brass). This versatile alloy has earned its reputation as the benchmark for free-cutting brasses worldwide. Combining excellent strength, superior corrosion resistance, and unmatched machinability, CDA 360 Brass continues to be the alloy of choice for high-volume, precision-engineered parts.
What is CDA 360 / C36000 Brass?
CDA 360 Brass is a copper-zinc-lead alloy belonging to the free-machining brass family. Its nominal composition is:
- Copper (Cu): ~61.5%
- Zinc (Zn): ~35.4%
- Lead (Pb): ~3.0%
- Iron (Fe): ≤0.35% (residuals up to 0.5%)
This balanced chemistry provides the best of three worlds:
- Copper contributes strength and corrosion resistance.
- Zinc enhances machinability and lowers cost.
- Lead acts as a built-in lubricant, improving chip formation and tool life.
The result is an alloy that is often described as “the free-cutting standard”. In fact, machinability ratings in metallurgy are benchmarked against CDA 360 Brass, which scores 100% machinability on the industry scale.
Key Properties of CDA 360 Brass
- Outstanding Machinability
- Cuts cleanly at high speeds with minimal tool wear.
- Produces small, easily removable chips—ideal for automated screw machines and CNC turning centers.
- Corrosion Resistance
- Performs well in mild industrial and atmospheric conditions.
- Resistant to dezincification, making it suitable for plumbing and fluid-handling parts.
- Strength and Hardness
- Tensile strength: ~58,000 psi (annealed) up to 80,000 psi (cold-drawn).
- Brinell hardness: ~80–100 HB.
- Excellent Surface Finish
- Parts machined from CDA 360 Brass can be polished, plated, or left natural with a bright metallic sheen.
Typical Parts Made from CDA 360 Brass
Thanks to its machinability and performance, CDA 360 Brass is widely used for precision, high-volume components, such as:
- Screw machine parts
- Connectors and terminals (electrical and mechanical)
- Valve bodies and fittings
- Plumbing fixtures
- Fasteners (nuts, bolts, threaded inserts)
- Instrumentation components
- Automotive parts (fuel system fittings, hydraulic couplings)
- Aerospace hardware
- Architectural hardware and decorative trim
Essentially, if a part requires tight tolerances, repetitive machining, and reliability, CDA 360 is often the go-to alloy.
Machining CDA 360 Brass
CDA 360 is the reference alloy for machinability—engineers compare other alloys to it. Here’s why it performs so well in machining operations:
- Free-Cutting Action: The ~3% lead in the microstructure acts like tiny “ball bearings,” breaking chips and lubricating the cutting tool.
- High-Speed Friendly: Ideal for automatic screw machines, CNC lathes, and multi-spindle turning centers.
- Surface Quality: Produces a smooth, burr-free finish with little need for secondary polishing.
- Tool Life: Lead reduces tool wear, enabling longer runs and lower tooling costs.
- Threading & Tapping: Cuts threads crisply without tearing, essential for precision fasteners.
For these reasons, CDA 360 is often described as a “machine operator’s dream alloy.”
Why CDA 360 Brass is Considered Superior
- Machinability Benchmark
- Rated 100% machinable, it is the alloy against which all others are compared.
- Cost-Effective
- Zinc lowers material cost compared to pure copper, while maintaining good performance.
- Balanced Performance
- Good strength, excellent finish, and corrosion resistance all in one alloy.
- Versatility
- Works equally well for plumbing, automotive, aerospace, electrical, and decorative markets.
- Consistency
- Known for dimensional stability and repeatability in high-volume production runs.
Limitations to Consider
While CDA 360 Brass is highly versatile, there are a few caveats:
- Not recommended for marine or strong acid environments (aluminum bronze or silicon bronze perform better there).
- Lead content (~3%) makes it unsuitable where lead-free regulations apply (e.g., potable water fittings in some regions require lead-free brass such as C69300 ECO Brass).
Final Thoughts
CDA 360 (C36000) Brass remains one of the most widely used and trusted alloys in modern manufacturing. With its unbeatable machinability, reliable mechanical properties, and adaptability across industries, it continues to be the preferred choice for engineers and machinists worldwide.
Whether you are producing millions of tiny screw machine parts or custom precision components, CDA 360 Brass offers the best combination of performance, cost-efficiency, and reliability.
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