Brass C38500 | 2.0401 | CuZn39Pb3

Overview: UNS C38500 brass, widely known as Architectural Bronze or Free-Cutting Brass, is a premium leaded copper-zinc alloy tailored for high-efficiency CNC machining, stable corrosion resistance, and elegant golden brass appearance. Balancing excellent processability and mechanical performance, it is ideal for complex machined profiles, architectural decorative hardware, industrial fittings and high-volume precision parts. As a professional precision CNC machining manufacturer, Evefab leverages mature C38500 processing technology to deliver stable, high-quality batch production and customized precision machining solutions.

1. Basic Material Information

C38500 is a classic leaded free-machining brass. The added lead element optimizes chip breaking performance, effectively reduces cutting resistance and tool wear, and greatly improves the efficiency of automatic machining and CNC turning/milling compared with ordinary brass. It integrates excellent machinability, moderate structural strength, good dimensional stability and decorative metallic appearance, covering dual application scenarios of industrial precision parts and architectural decorative hardware.

1.1 Global Standard Designations

C38500 has unified industry naming specifications. Evefab strictly verifies material grades according to customer drawing standards to avoid material substitution errors:

1.2 Important Grade Distinction Note

C38500 cannot be interchangeably used with CuZn39Pb3/CW614N (C36000). Although both are leaded free-cutting brasses, they differ in chemical component limits, mechanical performance standards and applicable scenarios. CDA clearly classifies C38500 as Architectural Bronze and C36000 as professional free-cutting brass, which are two independent UNS alloy grades. Evefab strictly abides by drawing specifications for material selection to ensure part compliance.

1.3 Material Core Positioning

• Alloy Category: Copper-zinc-lead leaded free-machining brass

• Core Advantages: Excellent CNC machinability, stable dimensional repeatability, good atmospheric corrosion resistance, exquisite golden appearance

• Applicable Scenarios: Precision mechanical parts, architectural decorative hardware, fluid control fittings, high-volume automatic machined parts

• Performance Defect: Lower electrical and thermal conductivity than pure copper (C101/C110), not suitable for high-current conductive and high-efficiency heat dissipation parts

2. Physical Properties of C38500 Brass

The following data are typical engineering reference values. The actual physical and mechanical properties of C38500 are affected by material temper, section size and processing technology. Evefab matches the most suitable material status and processing parameters according to part functional requirements.

2.1 Basic Physical Parameters

2.2 Mechanical Properties

The strength, hardness and ductility of C38500 vary significantly with cold working degree and annealing temper:

• Tensile Strength: 350–500 MPa

• Yield Strength: 150–300 MPa

• Elongation: 10–30%

• Hardness: 60–100 HRB (varies with material condition; cold-worked materials have higher hardness and strength)

For parts with strict mechanical performance requirements, Evefab will clarify material temper in the processing scheme to ensure consistent mechanical properties of batch products.

2.3 Temperature & Service Limitations

Although C38500 has a high melting point, long-term high-temperature service will lead to decreased strength, increased thermal expansion, reduced dimensional stability and aggravated surface oxidation. For precision components working in elevated temperature environments, Evefab recommends optimizing material selection and processing technology according to actual working conditions.

3. Chemical Properties & Compliance Specifications

3.1 Typical Chemical Composition

C38500 is a leaded brass with controllable lead content. Moderate lead addition fundamentally optimizes the machining performance of the alloy, realizing short chip cutting, low cutting force and long tool life:

3.2 Corrosion Resistance & Application Restrictions

C38500 has excellent atmospheric corrosion resistance, suitable for indoor industrial environments, architectural decoration, general hardware and conventional fluid fitting scenarios. The surface will naturally form a protective oxide patina after long-term environmental exposure.

Unsuitable Working Conditions: Strong acid, strong oxidation, ammonia-containing, high-chloride and marine harsh environments, which are prone to corrosion and dezincification. For long-term immersed fluid equipment and drinking water system parts, alternative corrosion-resistant alloys are recommended.

3.3 Environmental Regulatory Compliance

C38500 contains intentional lead to improve machinability, so it is restricted by RoHS, REACH, California Proposition 65 and other environmental regulations. It is not applicable to food contact, medical equipment, pure drinking water and other regulated scenarios.Evefab actively reminds customers of material compliance risks and provides compliant material replacement schemes for export and regulated products.

3.4 Welding & Connection Performance

Due to lead composition characteristics, C38500 is not suitable for conventional fusion welding, which is prone to welding defects. The recommended connection methods are mechanical fastening, brazing and soldering with stable quality and no damage to material performance.

4. CNC Machinability Analysis of C38500

Overall Machining Difficulty: Easy

As a high-performance free-cutting brass, C38500 has excellent comprehensive machining performance, far superior to pure copper materials. It features clean chip breaking, low cutting resistance, no material smearing and stable processing quality, and is compatible with almost all CNC precision machining processes.

4.1 Recommended Tooling & Geometry

Evefab adopts customized tool matching schemes for C38500 batch processing to improve efficiency and yield:

• Conventional Processing: High-speed steel tools, ordinary carbide tools

• High-Precision Batch Production: Polished positive-rake carbide tools, special brass chip-breaking inserts

• Tool Core Requirements: Sharp cutting edge, sufficient clearance, excellent chip evacuation performance

4.2 Reference CNC Cutting Parameters

The following are universal starting parameters for carbide tooling. Evefab dynamically optimizes parameters according to tool specification, part structure and surface finish requirements:

4.3 Common Machining Problems & Solutions

Burr & Edge Defects

Fine burrs are easy to appear at hole exits, thin walls and sharp corners.
Evefab Solution: Equip sharp new tools, optimize feed parameters, reserve process chamfers, and support automatic deburring and fine finishing.

Tool Wear & Dimensional Drift

Long-term batch processing causes tool wear, resulting in dimensional deviation and poor thread quality.
Evefab Solution: Regularly monitor tool life, set wear compensation, and use special brass cutting fluid to reduce tool loss.

Vibration Chatter & Surface Scratches

Excessive tool overhang and unstable clamping cause chatter and surface tool marks.
Evefab Solution: Optimize tool extension length, upgrade fixture stability, and avoid chip recutting to protect decorative surfaces.

4.4 Machining Tolerance & Surface Finish Capability

Relying on mature C38500 processing technology, Evefab stably achieves high-precision manufacturing standards:

• Conventional dimensional tolerance: ±0.05 mm

• Precision key feature tolerance: ±0.01–0.02 mm

• Conventional surface roughness: Ra 0.8–3.2 μm

• Ultra-fine decorative finishing: Ra ≤0.4 μm

4.5 Machining Scenario Suitability

5. Typical Application Fields & Parts

5.1 Architectural Decorative Hardware

Relying on exquisite golden appearance and fine machining performance, C38500 is the preferred material for high-end architectural hardware: door and window accessories, decorative fittings, handles, architectural brackets, furniture hardware and visual decorative parts.

5.2 Plumbing & Fluid Control Components

Widely used in industrial valves, pipe fittings, adapters, connectors and nozzle parts. It balances machining efficiency and corrosion resistance, suitable for general fluid control scenarios (not recommended for drinking water systems).

5.3 Industrial Automation Parts

Suitable for pneumatic and hydraulic fittings, sensor housings, bushings, shafts, couplings and precision mechanical connectors. It significantly reduces batch production cycle time and manufacturing cost.

5.4 Automotive Mechanical Parts

Used for automotive fluid adapters, sensor hardware, threaded connectors and mechanical spacers. It requires strict verification of chemical compatibility and environmental regulations for fuel and coolant contact parts.

5.5 Electrical & Instrument Components

Applicable for connector shells, terminals, cable accessories and instrument hardware. It is only used for mechanical electrical parts, not for high-current conductive and heat dissipation components.

5.6 Fasteners & Consumer Precision Parts

Ideal for high-volume machined nuts, screws, studs, threaded inserts and precision assembly parts, as well as instrument knobs, camera hardware and small decorative mechanical assemblies.

6. Evefab C38500 Brass CNC Machining Core Advantages

6.1 Professional Grade Distinction & Material Verification

Evefab engineering team accurately distinguishes easily confused brass grades such as C38500, C36000, C37700 and CW614N, completely avoiding material substitution errors. We provide official MTR material test reports and full batch traceability records to meet global customer compliance requirements.

6.2 High-Efficiency Batch Production Optimization

Aiming at the excellent machinability of C38500, we customize exclusive high-speed processing schemes, optimize spindle speed, feed rate and chip breaking parameters, greatly shorten single-piece cycle time, reduce tool loss, and realize low-cost and stable mass production from prototype to large batch.

6.3 Full-Cycle Precision Machining Capacity

Support full-process processes such as CNC turning, Swiss precision machining, multi-axis milling, tapping, knurling and fine finishing. Integrate turning and milling composite processing to reduce clamping errors and meet the processing requirements of small, complex and high-precision decorative parts.

6.4 Professional DFM Cost Optimization

Evefab provides free DFM manufacturability review for C38500 part drawings, optimizes unreasonable tolerance allocation, corner structure and wall thickness design, ensures product functionality, and effectively reduces unnecessary processing costs for customers.

6.5 Diversified Surface Finishing Services

Provide supporting secondary treatments such as deburring, polishing, wire drawing, tumbling, nickel plating and chrome plating, to meet the dual needs of industrial assembly and high-end decorative appearance of C38500 parts.

6.6 Complete Quality Control System

Equipped with CMM precision detection, GD&T geometric tolerance verification, thread gauge detection and surface roughness testing, with full-process quality inspection and batch traceability system to ensure 100% qualified delivery of parts.

7. Grade Comparison: C38500 vs C36000

The two are both high-performance free-cutting brasses with similar machining performance, but cannot be interchanged in engineering applications:

Engineering Summary & Recommendation

C38500 (Architectural Bronze) is a cost-effective leaded free-cutting brass, integrating excellent CNC machinability, good corrosion resistance, moderate mechanical strength and high-value decorative appearance. It is widely used in architectural hardware, fluid control fittings, industrial automation parts, automotive mechanical components and precision fasteners.

Evefab Engineering Recommendation: C38500 is the preferred material for high-volume machined decorative parts and general industrial precision parts. Due to its lead composition, it is forbidden to be used in food contact, medical and drinking water regulated scenarios. For customized precision processing and batch production needs, please contact Evefab for free DFM analysis, material verification and accurate quotation.

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