C36000 brass, also known as free-cutting brass, is a Cu–Zn–Pb alloy that is prized for how easy it is to work with, how precise it is, and how smooth its surface is. It has 60% copper, 36% zinc, and 3% lead, and it is the standard for CNC-machined parts like fittings, valves, and hardware. This article gives important information about how easy it is to machine C36000 brass, how to treat its surface, and how to make sure it meets environmental standards. This helps engineers make parts for modern manufacturing that are strong, long-lasting, and meet all the rules.
What is C36000 brass？
C36000 brass, also called free-cutting brass or 360 brass, is a copper–zinc–lead alloy that is made to be very easy to machine and make things with high precision. This is the most common type of brass used for automatic lathes and CNC machining. It makes smooth chips, wears down tools less, and has a shiny finish.
Key facts:
-
Material type: Free-machining copper alloy (Cu–Zn–Pb)
-
Typical composition: ~60% Cu, ~36% Zn, ~3% Pb
-
Density: 8.49 g/cm³
-
Tensile strength: 350–500 MPa (annealed to cold-drawn)
-
Hardness: 80–160 HB depending on temper
-
Machinability: 100% (reference standard for all copper alloys)
-
Corrosion resistance: Good in dry air and freshwater; not suitable for strong acids or ammonia environments
Typical applications:
-
Precision-machined parts (fittings, valves, fasteners, connectors)
-
Plumbing and fluid systems
-
Decorative and hardware components
In short, C36000 brass is the best material for machinability because it has a high cutting efficiency, stays stable in size, and has a better surface finish. Because it contains lead (2.5–3.0%), though, it must meet safety and environmental standards like RoHS, REACH, and NSF/ANSI 61 for use with food or drinking water.
Brass C360 vs C36000
Both terms—Brass C360 and C36000 brass—refer to the same alloy, with “C36000” being the official UNS designation. In different standards:
-
ASTM / UNS: C36000
-
SAE / CDA: Alloy 360
-
JIS / EN equivalents: C3601 / CW603N
This naming distinction ensures cross-compatibility in global sourcing and specification alignment, allowing manufacturers to confidently substitute materials across regions while maintaining consistent C36000 brass properties.
Material Overview and Chemical Composition
Alloy Classification and Standards
C36000 brass, also known as Free-Cutting Brass or Alloy 360, is a copper–zinc–lead alloy designed specifically for high-speed machining applications. It is the reference material for 100% machinability rating—the industry benchmark used to compare other metals’ cutting performance.
C36000 belongs to the α + β two-phase brass family, where the α-phase (Cu-rich solid solution) ensures ductility and corrosion resistance, while the β-phase (Zn-rich) contributes to hardness and strength. The addition of finely distributed lead (Pb) particles provides natural lubrication and chip fragmentation, allowing for smooth machining and superior surface finish.
Standard Designations
| System / Standard | Designation | Notes |
| UNS (USA) | C36000 | Unified Numbering System designation |
| ASTM | B16 / B124 / B453 | Standard for free-cutting brass rods and bars |
| ISO / EN | CuZn39Pb3 / CW603N | Equivalent under European and ISO standards |
| CDA (Copper Development Association) | Alloy 360 | North American commercial name |
| BS / DIN | CZ121 / CuZn39Pb3 | British and German equivalents |
Common Supply Forms: Round and hexagonal bars, tubes, profiles, and forgings, typically in drawn, extruded, or machined condition. These forms are optimized for automatic lathes, CNC turning, and precision screw machining industries.
Engineering Insight: C36000’s combination of strength, ductility, and machinability has made it the standard alloy for high-volume production of precision components, particularly where tight tolerances, smooth surfaces, and corrosion resistance are required.
Chemical Composition and Alloying Roles
The balanced composition of C36000 brass ensures both excellent machinability and sufficient mechanical integrity for medium-load components. Lead acts as a chip breaker, while zinc provides strength and cost efficiency, making it one of the most economical high-performance brasses available.
| Element | Content (%) | Engineering Function |
| Cu (Copper) | 60.0–63.0 | Forms the primary matrix, offering strength, corrosion resistance, and electrical conductivity. |
| Pb (Lead) | 2.5–3.0 | Provides exceptional machinability by forming discrete particles that reduce cutting friction and enable chip fragmentation. |
| Zn (Zinc) | Balance (~35–37) | Increases strength, reduces cost, and stabilizes α + β phases for enhanced mechanical performance. |
| Fe (Iron) | ≤0.35 | Minor impurity; excessive levels may slightly reduce corrosion resistance and surface polishability. |
| Others (Sn, Al, Ni, etc.) | ≤0.20 | Trace elements that refine grain size and improve thermal stability during processing. |
Microstructural Interpretation
-
The α-phase (Cu-rich) provides ductility and toughness.
-
The β-phase (Zn-rich) adds strength and hardness.
-
Pb inclusions act as micro-lubricants, reducing tool wear and improving finish quality.
Physical and Mechanical Properties
C36000 brass demonstrates an optimal combination of mechanical strength, thermal conductivity, and dimensional stability, suitable for both functional and aesthetic components in mechanical, electrical, and decorative applications.
| Property | Value / Range | Engineering Significance |
| Density (ρ) | 8.5 g/cm³ | High density supports vibration damping and rigidity. |
| Thermal Conductivity | 120 W/m·K | Excellent heat dissipation; ideal for thermal or fluid components. |
| Electrical Conductivity | ~26% IACS | Suitable for low-current connectors and electrical fittings. |
| Tensile Strength (σb) | 360–480 MPa | Provides adequate strength for mechanical fittings and precision parts. |
| Yield Strength (σy) | 180–340 MPa | Ensures elastic recovery and dimensional stability under stress. |
| Hardness (HB) | 80–100 | Easy to machine yet sufficiently strong for service wear. |
| Elongation (δ) | 25–30% | Good ductility, suitable for cold forming and secondary operations. |
| Elastic Modulus (E) | ~105 GPa | Predictable stiffness for precise dimensional tolerances. |
| Thermal Expansion Coefficient | 19.9 µm/m·K | Stable under thermal cycling; minimizes distortion in multi-material assemblies. |
Engineering Summary
C36000 brass offers:
-
Machinability = 100%, with short chip formation and minimal tool wear.
-
Moderate strength sufficient for most industrial fittings and mechanical connectors.
-
Excellent corrosion resistance in air, water, and mild industrial environments.
-
Dimensional stability that supports tight-tolerance machining and precision assembly.
Microstructure and Metallurgical Behavior
Microstructure Characteristics
C36000 brass (free-cutting brass) exhibits a characteristic α + β dual-phase microstructure with finely dispersed lead (Pb) particles distributed throughout the grain boundaries. The α-phase is a Cu-rich solid solution, providing ductility and corrosion resistance, while the β-phase is a Zn-rich solid solution, contributing to hardness and strength.
The lead phase exists as spherical or globular inclusions that do not dissolve in the Cu–Zn matrix. These Pb inclusions act as natural lubricants and chip breakers, promoting smooth machining and excellent surface finish.
| Phase | Composition / Nature | Function in Machining and Service |
| α (Alpha) | Cu-rich (≈63% Cu) | Ductility, corrosion resistance, thermal stability |
| β (Beta) | Zn-rich (≈37% Zn) | Hardness, strength, and dimensional stability |
| Pb (Lead) | Insoluble, discrete phase | Acts as internal lubricant; facilitates chip fragmentation and lowers cutting force |
Microstructural Description: Under an optical microscope (etched surface), α appears as bright grains, β as darker regions, and Pb as round black inclusions distributed along grain boundaries. This triphasic structure ensures both machinability and functional durability, explaining why C36000 brass remains the global standard for automatic lathe and CNC machining alloys.
Influence of Lead Distribution
The distribution and morphology of Pb inclusions play a decisive role in the alloy’s machinability, surface quality, and fatigue strength. Ideally, the lead particles should be finely and uniformly dispersed along grain boundaries without forming elongated clusters or segregation zones.
Effects of Lead Distribution:
| Distribution Type | Microstructural Effect | Engineering Consequence |
| Uniform, fine dispersion | Even chip fragmentation and lubrication during cutting | → Reduced cutting force, lower tool wear, improved Ra (surface roughness ≤ 0.8 µm) |
| Localized segregation or clustering | Formation of Pb pools or voids after extrusion or overheating | → Risk of porosity, microcracks, and corrosion initiation points |
| Depleted zones (Pb-poor regions) | Loss of lubricating phase | → Increased friction, poor machinability, inconsistent finish |
The uniform presence of lead globules at grain boundaries enhances chip segmentation and prevents tool adhesion (built-up edge formation), maintaining dimensional accuracy and extending tool life by 20–40% compared to lead-free brasses.
However, excessive lead segregation or Pb-rich zones can cause surface defects, fatigue crack initiation, and dezincification corrosion in humid or chloride-rich environments.
Engineering Note: During extrusion or hot forging, process control should maintain homogeneous Pb dispersion through proper billet preheating (≤650°C) and extrusion ratio optimization. Non-uniform distribution can drastically reduce fatigue strength by up to 25%.
Thermal and Structural Stability
C36000 brass possesses excellent thermal conductivity (≈120 W/m·K), allowing rapid heat dissipation during machining or forming. This property supports tight thermal control and prevents localized overheating. However, because of the alloy’s multi-phase structure and low Pb melting point (327°C), temperature management is critical during hot processing and brazing.
Key Thermal Behavior and Processing Guidelines:
| Thermal Parameter | Typical Value / Limit | Engineering Implication |
| Thermal Conductivity | ~120 W/m·K | Excellent heat dissipation; stable during cutting |
| Pb Melting Point | 327°C | Risk of Pb liquation if overheated during forging or brazing |
| Hot Work Range | 600–700°C | Safe temperature window for extrusion and forging |
| Overheating Threshold | >700°C | Pb melts and migrates along grain boundaries, causing exudation and void formation |
| Recommended Cooling | Controlled air or oil mist | Prevents thermal shock and Pb segregation |
During hot working, exceeding 700°C can cause lead exudation (“sweating”), forming microvoids that impair surface finish and mechanical properties. To avoid this:
-
Maintain a controlled preheat and die temperature (≤680°C),
-
Employ short dwell times, and
-
Use lubricants compatible with Cu–Zn alloys to minimize frictional heat.
Structural Stability Under Service Conditions
C36000 maintains microstructural integrity and mechanical strength in typical service environments up to 200°C. Beyond this, prolonged exposure may lead to:
-
Grain coarsening in the β-phase,
-
Slight reduction in hardness, and
-
Minor color change due to oxidation of zinc-rich regions.
Design Insight: For components operating in elevated temperature conditions (e.g., valve bodies or fluid connectors), stress-relief annealing at 250–300°C is recommended to reduce residual stress while preserving dimensional accuracy.
Machinability and Manufacturing Guidelines
Cutting Behavior and Machinability Rating
C36000 brass is the industry benchmark for machinability, assigned a machinability index of 100, against which the cutting performance of all other alloys is compared. This rating stems from its unique Cu–Zn–Pb microstructure, where the lead phase acts as a natural chip breaker and internal lubricant.
During machining, chips fragment easily into short, powdery or granular forms, effectively preventing chip entanglement and ensuring smooth automatic operation in multi-spindle screw machines and high-speed CNC lathes. The cutting forces are low, tool wear is minimal, and surface finishes below Ra 0.8 µm can be routinely achieved without secondary polishing.
Key Machining Advantages:
-
Outstanding chip control: Breaks chips into fine segments, ideal for continuous automatic feeding.
-
Low tool wear: Pb inclusions reduce friction and temperature at the cutting edge.
-
High productivity: Enables cutting speeds up to 250 m/min on carbide tools.
-
Excellent surface finish: Facilitates bright, smooth surfaces suitable for direct plating or decorative use.
Engineering Note: Because of its stable microstructure and low work-hardening rate, C36000 brass maintains dimensional consistency across long production runs, minimizing tool offsets and post-machining distortion.
Recommended Machining Parameters
To fully leverage its machinability, tool geometry, lubrication, and cutting parameters should be optimized for high-speed, precision machining. The following table summarizes recommended conditions for typical operations:
| Process | Cutting Speed (m/min) | Feed Rate (mm/rev) | Tool Material | Lubrication Recommendation |
| Turning | 120–250 | 0.05–0.25 | P20-grade carbide | Water-based emulsion or MQL (minimum quantity lubrication) |
| Milling | 150–250 | 0.05–0.20 | TiAlN-coated carbide | Spray mist or oil mist cooling |
| Drilling | 80–120 | 0.05–0.15 | HSS or TiN-coated drill | Oil-based coolant for chip evacuation |
| Tapping | 10–30 | — | TiN-coated taps | Low speed, continuous lubrication with tapping oil |
Additional Machining Notes:
-
Tool Geometry: Positive rake angles (10–15°) and sharp cutting edges further enhance chip flow and reduce built-up edge formation.
-
Coolant Selection: Although machinable without coolant, emulsion or mist lubrication improves tool life and surface brightness.
-
Dimensional Accuracy: Stable α + β matrix ensures excellent tolerance control (±0.01 mm achievable).
-
Tool Wear Mechanism: Primarily adhesive and mild abrasive — negligible compared to steels or aluminum alloys under similar cutting conditions.
Forming, Joining, and Heat Treatment
C36000 brass is not only easy to machine but also moderately formable and well-suited for secondary fabrication processes such as bending, rolling, and joining — provided temperature and tooling parameters are carefully controlled.
Cold Working Behavior
-
Cold Workability: Excellent — suitable for cold bending, thread rolling, knurling, and light stamping.
-
Exhibits low strain hardening, allowing for multiple forming operations without cracking.
-
Ideal for precision fittings, threaded connectors, and small hardware components requiring tight dimensional control.
Hot Working Characteristics
-
Hot Formability: Moderate — optimal working temperature range 650–700°C.
-
Overheating above 700°C may cause Pb exudation (“sweating”), leading to surface defects and porosity.
-
For extrusion or hot forging, preheat billets uniformly and minimize dwell time at peak temperature.
Joining and Welding
-
Weldability: Poor for fusion welding due to Pb segregation and Zn vaporization.
-
Recommended joining methods:
-
Brazing or silver soldering (preferred for leak-free joints in fluid systems).
-
Soft soldering for low-temperature electrical or decorative applications.
-
-
Surface preparation: Degreasing and light abrasion improve wetting during brazing.
Note: When joining, use Cu–Ag–Zn or Ag–P–Cu filler alloys with neutral flux to prevent zinc loss and oxidation.
Heat Treatment and Supply Condition
-
Supplied Condition: Typically cold-drawn, extruded, or annealed for ease of machining and forming.
-
Heat Treatment:
-
No hardening through heat treatment (non-heat-treatable alloy).
-
Annealing possible at 450–600°C to restore ductility after extensive cold work.
-
Rapid cooling post-annealing prevents coarse grain growth.
-
Engineering Summary:
-
Machinability: Benchmark rating 100 – unmatched in cutting performance and tool efficiency.
-
Formability: Excellent in cold state, moderate in hot working with temperature control.
-
Weldability: Limited; brazing is the preferred joining method.
-
Thermal Guidelines: Maintain forming temperatures below 700°C to avoid Pb exudation.
Surface Treatment and Corrosion Performance
Surface Finishing Compatibility
C36000 brass offers outstanding compatibility with a wide range of surface finishing and coating processes, making it suitable for both functional and decorative applications. Its fine-grained α + β matrix and uniform Pb dispersion allow for smooth polishing and excellent plating adhesion—provided proper pre-treatment is performed.
Commonly applied finishing processes include mechanical polishing, nickel/chrome electroplating, sandblasting, chemical passivation, and cleaning treatments for precision components.
Surface Finishing Capabilities:
| Process | Feasibility | Purpose / Effect |
| Polishing | Excellent | Achieves mirror or decorative-grade surface finish (Ra ≤ 0.05 µm) |
| Nickel Plating (Electro / Electroless) | Excellent | Improves wear resistance, brightness, and corrosion protection |
| Chrome Plating | Excellent | Adds hard, corrosion-resistant outer layer, enhances aesthetics |
| Sandblasting / Bead Blasting | Good | Produces matte surface for uniform plating or coating adhesion |
| Chemical Passivation | Moderate | Reduces oxidation during storage or humid conditions |
| Ultrasonic Cleaning | Recommended | Removes residual oxides, Pb smears, and machining oils before coating |
Engineering Note: Prior to plating, surfaces should be mechanically cleaned and chemically activated to remove any lead residues or oxides, which can cause plating adhesion failures. A mild acid pickle (e.g., 10% HCl for a few seconds) is commonly used, followed by rinsing and immediate immersion in plating solution.
Because of its excellent polishability, C36000 brass is widely chosen for architectural hardware, lighting fixtures, decorative trims, and instrument housings, where both aesthetic quality and corrosion stability are required.
Corrosion and Wear Behavior
C36000 brass demonstrates good corrosion resistance in atmospheric, freshwater, and mild industrial environments, owing to the formation of a thin, adherent Cu–Zn oxide film on its surface. This natural patina provides moderate protection against further oxidation and tarnishing.
However, the alloy is not suitable for ammonia-bearing, saline, or sulfide-rich environments, where stress corrosion cracking (SCC) or dezincification may occur.
Environmental Resistance Summary:
| Environment | Performance | Notes |
| Atmosphere (dry / humid) | Excellent | Stable oxide layer prevents corrosion and tarnish |
| Fresh water / tap water | Good | Common for plumbing fittings and valves |
| Ammonia or ammonium compounds | Poor | Susceptible to stress corrosion cracking (avoid use) |
| Sea water / saline vapor | Poor | Dezincification and pitting possible |
| Sulfur compounds / industrial gases | Fair | Surface darkening and Pb oxidation may occur |
The Pb phase in the microstructure contributes to solid lubrication during sliding contact or threaded assembly, reducing friction and galling. This makes C36000 ideal for low-speed rotary fittings, valve seats, and mechanical connectors, where self-lubrication extends service life.
Practical Insight: In rotating or mating components, the presence of fine Pb inclusions can reduce the coefficient of friction by up to 40% compared to lead-free brasses, particularly under dry or marginally lubricated conditions.
Surface Hardening or Coating Options
Although C36000 brass cannot be thermally hardened, its surface performance can be enhanced through electroplated coatings or thin-film deposition techniques. These methods improve corrosion resistance, reduce wear, and enhance visual appeal for both engineering and consumer-grade components.
| Treatment / Coating | Key Features | Typical Applications |
| Nickel Plating (Ni) | Improves wear resistance, brightens surface, provides moderate corrosion protection | Electrical connectors, decorative hardware, fluid fittings |
| Chrome Plating (Cr) | Excellent corrosion and tarnish resistance, high hardness (HRC 60+) | Plumbing components, aerospace fluid connectors |
| PVD Coating (TiN / CrN / DLC) | Reduces friction coefficient, enhances wear and fatigue resistance | Valve cores, seals, high-precision threaded parts |
| Anodic Coating / Conversion Film | Provides electrochemical protection and color stability | Automotive and decorative applications |
Nickel–chrome duplex plating is particularly effective for exterior-grade hardware, combining the brightness of nickel with the hardness and chemical stability of chromium. For functional wear parts, DLC (Diamond-Like Carbon) or CrN coatings significantly reduce adhesive wear and galling, extending component lifespan under sliding or rotational stress.
Process Control Tip: Surface treatments should always be performed after final machining and cleaning to prevent contamination. For high-precision assemblies, coating thickness (typically 5–15 µm) should be considered in the final dimensional design.
Engineering Summary
-
Surface finish quality: Excellent polishability and plating adhesion enable mirror-grade surfaces.
-
Corrosion behavior: Strong resistance to air and freshwater; avoid ammonia or seawater exposure.
-
Functional coatings: Ni, Cr, or PVD films enhance wear, corrosion resistance, and aesthetics.
-
Design takeaway: C36000 brass offers a unique balance between machinability, decorative appeal, and corrosion stability, making it a versatile material for valves, fittings, instrumentation housings, and luxury hardware.
Environmental and Regulatory Compliance
Lead Content and Safety Considerations
C36000 brass contains 2.5–3.0% lead (Pb), which is essential for its excellent machinability but also introduces regulatory restrictions due to environmental and health concerns. Lead acts as a free-cutting agent that lowers friction and improves chip breakage, yet its presence limits usage in potable water, food-contact, and medical device applications.
Key Regulatory Constraints:
| Regulation / Standard | Limit | Impact on C36000 Usage |
| RoHS (EU Directive 2011/65/EU) | Pb ≤ 0.1% (by weight) | Exceeds limit; exemptions only for machining alloys in non-consumer applications |
| REACH (Annex XVII) | Restricts intentional Pb use > 0.1% | Requires labeling and exposure risk documentation |
| NSF/ANSI 61 (USA) | “Lead-free” = Pb ≤ 0.25% in wetted surfaces | Not compliant for drinking water systems |
| California Prop 65 | Requires lead exposure warnings | Applies to brass plumbing and decorative parts |
| Japanese JIS H3250 (Water Supply) | Pb ≤ 0.1% | Not suitable for domestic water fittings |
Low-Lead and Lead-Free Alternatives
To comply with tightening global environmental regulations, several low-lead and lead-free brass alloys have been developed as drop-in replacements for C36000, offering varying balances between machinability, corrosion resistance, and cost.
| Alloy | Pb Content (%) | Type | Key Features and Applications |
| C35300 (Low-Lead Brass) | 1.8 | Reduced-lead | Retains ~85% of C36000’s machinability; suitable for general hardware and valves |
| C34500 (Semi-Eco Brass) | 1.5 | Low-lead | Balanced approach for cost-sensitive, non-potable applications |
| C69300 (ECO BRASS) | ≤0.09 | Lead-free (Si-brass) | Excellent corrosion resistance; compliant with NSF/ANSI 61 for drinking water |
| C27450 (Green Brass) | ≤0.1 | Lead-free | Superior dezincification resistance; RoHS and REACH compliant |
| C46500 (High-Strength Eco Brass) | 0 | Lead-free | High strength and ductility; good for precision hydraulic and plumbing systems |
C69300 ECO BRASS (CuZn21Si3P) has become the most widely accepted lead-free alternative to C36000, combining machinability, corrosion resistance, and regulatory compliance. Although machining speed drops by approximately 10–15%, it remains the standard alloy for valve bodies, fittings, and fluid connectors in potable water systems.
Engineering Note: While C36000 offers superior cutting performance, modern lead-free alloys achieve comparable productivity through optimized Si-based microstructures and advanced cutting tool coatings (TiB₂, TiAlN).
Compliance Recommendations for Manufacturers
Manufacturers and exporters using C36000 brass must proactively manage regulatory documentation, supply chain control, and design modifications to ensure compliance with regional environmental laws.
Best Practices for Global Compliance:
-
Material Traceability and Certification
-
Maintain Material Test Certificates (MTC) from certified suppliers.
-
Ensure chemical composition testing confirms lead levels for each batch.
-
Provide RoHS and REACH declarations for all export orders.
-
-
Application Segregation
-
Use C36000 brass strictly for industrial and non-potable applications (e.g., pneumatic fittings, electronic housings, precision connectors).
-
For potable water systems, specify C69300 or equivalent lead-free grades.
-
-
Protective Surface Engineering
-
Apply nickel/chrome plating, epoxy coatings, or anodic sealants to minimize Pb migration and surface oxidation.
-
Conduct Pb leach testing (per NSF 372 or GB/T 17219) if components are exposed to fluids.
-
-
Regulatory Documentation by Region
-
EU: RoHS, REACH SVHC reporting, CE compliance.
-
USA: NSF/ANSI 61, Prop 65 labeling.
-
Japan: JIS H3250 water-contact regulation.
-
China: GB/T 3953 (lead-restricted brass for sanitary parts).
-
-
Process Optimization for Low-Lead Transition
-
Recalibrate cutting parameters when shifting to low-lead alloys (reduce feed by 10–20%, increase coolant flow).
-
Use high-precision carbide tools and sharp rake geometries to offset reduced lubricity in lead-free brass.
-
Design Tip: Even for industrial components, surface sealing and proper storage reduce oxidation and Pb surface exposure, extending product longevity and improving compliance perception.
Engineering Summary
-
C36000 brass offers unmatched machinability but contains ~3% lead, limiting its use in regulated industries.
-
RoHS, REACH, and NSF 61 restrict high-lead alloys, especially for drinking water and food-contact applications.
-
Eco alternatives such as C69300 and C27450 meet compliance while maintaining acceptable machinability.
-
Manufacturers should maintain full traceability, certification, and coating strategies to mitigate lead-related risks.
Applications and Engineering Case Studies
Typical Applications
C36000 free-cutting brass is one of the most widely used copper alloys in precision machining, fluid systems, and decorative hardware, thanks to its combination of exceptional machinability, dimensional stability, and surface finish quality. It is particularly suited for automatic lathes and multi-spindle CNC production lines, where productivity and repeatability are critical.
Common Application Fields:
| Industry / Sector | Component Examples | Technical Highlights |
| Automatic Lathe Components | Nuts, couplings, threaded plugs, fittings | Excellent chip control and tool life enable high-volume manufacturing |
| Valves, Pumps, and Fluid Systems | Cartridge valve bodies, pump housings, control valve spools | Smooth sealing surfaces and tight dimensional tolerances |
| Electrical and Instrumentation | Connectors, sensor housings, precision tubes | Good conductivity, corrosion resistance, and plating compatibility |
| Architectural and Decorative Hardware | Lock cylinders, handles, hinges, window fittings | Superior polishability and stable aesthetics after plating |
Design Insight: In high-speed machining environments, C36000 reduces cycle times by up to 40% compared with stainless steel or bronze, offering both economic and engineering advantages for precision hardware and pneumatic components.
Case Study — Fluid Connector for Pneumatic Systems
Material: C36000 brass, annealed bar stock Component: High-precision pneumatic fluid connector Production Volume: 10,000 pcs/month
Manufacturing Route: Turning → Thread Rolling → Polishing → Nickel Plating
Performance Results:
-
Surface Roughness: Ra < 0.8 μm
-
Dimensional Accuracy: ±0.01 mm
-
Thread Consistency: >99.8% acceptable rate after 50,000 production cycles
-
Corrosion Resistance: >72-hour salt spray with Ni plating
Optimization Highlights:
-
Microstructure Uniformity Control: Adjusted billet extrusion and annealing schedule to achieve even Pb distribution, minimizing micro-pitting during polishing.
-
Plating Adhesion Improvement: Introduced pre-polishing and ultrasonic cleaning steps to remove Pb smears and oxides before nickel plating.
-
Tool Path Optimization: Reduced cutting forces by 15% through feed rate tuning (0.12 mm/rev) and adaptive coolant delivery, extending tool life by ~20%.
Result: The component achieved stable sealing performance in pneumatic systems up to 1.2 MPa, maintaining mechanical integrity and visual quality even after extended cyclic loading and chemical exposure.
Selection Guidance
When selecting brass alloys for different engineering and commercial applications, both mechanical requirements and regulatory constraints should be considered. C36000 remains the optimal choice for high-speed precision machining, while lead-free alternatives are necessary for potable or regulated environments.
| Usage Scenario | Recommended Alloy | Technical Rationale |
| High-speed machining / Mass production | C36000 (Free-Cutting Brass) | Benchmark machinability (index 100), excellent dimensional accuracy |
| Drinking water and plumbing systems | C69300 (Lead-free ECO Brass) | NSF/ANSI 61 compliant, corrosion-resistant, environmentally safe |
| Decorative hardware and fittings | C36000 + Nickel Plating | Superior polishability, mirror finish, bright aesthetic surface |
| High-load / Wear-intensive parts | C36000 + Hard Chrome Coating | Improved wear and fatigue resistance in valves and sliding interfaces |
Engineering Summary:
Summary
C36000 brass is a copper alloy that cuts easily and has great machinability, dimensional accuracy, and surface finish. It is the industry standard for parts for automatic lathes, fluid fittings, and decorative hardware. The Cu–Zn–Pb composition makes sure that chips form smoothly and that tools don’t wear out too quickly. However, the lead content (2.5–3.0%) means that you have to be very careful to follow RoHS, REACH, and NSF/ANSI 61 standards for safety and environmental responsibility. Controlling machining parameters, lead distribution, and surface finishing—like nickel or chrome plating—correctly improves both performance and long-term reliability.
Low-lead or lead-free options like C69300 ECO BRASS and C27450 Green Brass are good for the environment and can be used for export without losing strength or machinability. Manufacturers can make brass parts that are strong, high-quality, and ready for use that meet modern engineering and environmental standards by combining material selection, precision CNC machining, and production that focuses on compliance.
At RPS, we provide an end-to-end manufacturing solution—covering material selection, precision CNC machining, surface finishing, and compliance-oriented production—to help global clients achieve high-performance, regulation-ready, and cost-effective brass components.
FAQ
What is C36000 brass?
C36000 is a free-cutting copper–zinc–lead alloy, engineered for high-speed precision machining. Known as Alloy 360 or Free-Cutting Brass, it offers 100% machinability (the industry reference standard) and maintains a good balance of strength, ductility, and surface quality for industrial and decorative components.
What is the composition of C36000?
C36000 brass typically contains ~61.5% copper (Cu), ~3% lead (Pb), and ~35.5% zinc (Zn). Small amounts of iron (Fe ≤ 0.35%) and trace elements may be present to stabilize grain structure. Lead forms discrete globules within the matrix, improving chip breakage and cutting smoothness.
Why is C36000 easy to machine?
The lead inclusions in C36000 act as microscopic lubricants and chip breakers during cutting. This reduces tool friction and heat generation, leading to longer tool life, lower cutting forces, and smoother surface finishes. Its machinability rating is 100%, meaning it serves as the benchmark for evaluating other machining alloys.
Is C36000 brass safe for drinking water systems?
No. C36000 contains ~3% lead, which makes it unsuitable for potable water, food-contact, or medical applications. It does not meet RoHS or NSF/ANSI 61 limits for lead content. For such uses, lead-free alternatives like C69300 ECO BRASS or C27450 Green Brass are recommended.
What are alternatives to C36000?
-
C69300 (ECO BRASS): Lead-free, silicon-based, corrosion-resistant, NSF-certified for drinking water.
-
C27450 (Green Brass): Lead ≤0.1%, RoHS/REACH compliant, excellent dezincification resistance. These alloys maintain good machinability while satisfying modern environmental and regulatory requirements.
Can C36000 brass be plated or polished?
Yes. C36000 offers excellent plating and polishing compatibility. Its smooth surface and fine-grained structure allow nickel, chrome, and gold plating with strong adhesion. Polished finishes can reach mirror-grade (Ra ≤ 0.05 μm), making it ideal for decorative fittings, valves, and instrument housings.
About the Author: Gavin Xia
This article was written by engineers from the RAPID PROTOS team. Gavin Xia is a professional engineer and technical expert with 20 years of experience in rapid prototyping, metal parts, and plastic parts manufacturing.
