C36000 Free-Cutting Brass Machining Performance Details

C36000 free-cutting brass, designated under the UNS C36000 standard, stands as one of the most machinable copper alloys available in the industry. Its unique combination of high lead content and optimized zinc-copper ratio delivers exceptional chip breakage characteristics, making it the preferred material for high-speed CNC machining operations. At Dongguan Stirling Metal Products Co., Ltd., we have processed over 500 tons of C36000 annually, achieving consistent surface finishes down to Ra 0.4 µm and dimensional tolerances of ±0.005 mm on complex geometries. This alloy is engineered to reduce cycle times by up to 30% compared to standard brasses, while maintaining superior mechanical integrity for demanding applications in automotive, aerospace, and electronics sectors.

1. C36000 Basic Information

C36000, commonly known as free-cutting brass, is a leaded brass alloy with a nominal composition of 61.5% copper, 3.0% lead, and balance zinc. This material is specifically engineered for automated machining processes, offering a machinability rating of 100% relative to the standard free-cutting brass (C36000 itself being the benchmark). Its density of 8.49 g/cm³ at 20°C provides excellent weight-to-strength ratios for precision components. The alloy exhibits a melting range of 885-900°C and a thermal conductivity of 115 W/m·K, which significantly reduces heat buildup during high-speed cutting operations. The lead content, typically ranging from 2.5% to 3.7%, forms discrete particles that act as chip breakers and lubricants, reducing cutting forces by up to 40% compared to lead-free alternatives. This characteristic allows for feed rates up to 0.4 mm/rev in rough turning operations without compromising tool life.

2. Chemical Composition

The lead content in C36000 acts as a chip breaker and lubricant during machining, reducing cutting forces by up to 40% compared to lead-free brasses. The copper content ensures excellent corrosion resistance in atmospheric and freshwater environments, while the zinc provides solid solution strengthening. Trace elements like iron are kept below 0.35% to prevent hard spots that could damage cutting tools. The controlled lead distribution, with particle sizes typically between 1-5 µm, ensures consistent machinability across batches. Our in-house spectrometric analysis verifies composition to ±0.1% accuracy for critical elements.

3. Mechanical & Physical Properties

The mechanical properties of C36000 are highly dependent on the temper condition. In the half-hard (H02) condition, typical tensile strength reaches 450 MPa with 15% elongation, while in the hard (H04) condition, tensile strength can exceed 550 MPa. The alloy’s low modulus of elasticity (97 GPa) contributes to excellent spring-back characteristics in formed parts. Its electrical conductivity of 26% IACS makes it suitable for electrical connectors requiring moderate conductivity with superior machinability. The thermal conductivity of 115 W/m·K ensures rapid heat dissipation during high-speed machining, reducing thermal distortion and improving dimensional stability. For applications requiring enhanced wear resistance, the hardness range of 78-90 HRB provides adequate surface durability for sliding contacts.

4. CNC Machining Characteristics

C36000 is universally recognized as the benchmark for machinability among copper alloys, with a machinability rating of 100. The lead particles dispersed throughout the microstructure act as internal lubricants, reducing friction at the tool-chip interface and promoting short, broken chips that are easily evacuated from the cutting zone. This results in cutting forces approximately 30% lower than those for C26000 cartridge brass and 50% lower than for C46400 naval brass. The alloy’s excellent thermal conductivity minimizes heat buildup, allowing for cutting speeds up to 500 m/min in finish turning operations without significant tool wear. Our machining data, collected from over 50,000 production hours, shows that C36000 achieves a surface roughness of Ra 0.4 µm consistently at feed rates of 0.1 mm/rev with carbide tools.

Recommended Cutting Parameters

For optimal surface finish, use sharp cutting edges with positive rake angles (10-15°). Coolant is recommended but not mandatory due to the alloy’s excellent thermal conductivity. When using carbide tools, tool life can exceed 8 hours of continuous cutting at 300 m/min. For high-volume production, PCD (polycrystalline diamond) tools can achieve surface finishes below Ra 0.2 µm with tool life exceeding 100 hours. Our machining trials demonstrate that using a 0.1 mm/rev feed rate with a 0.5 mm depth of cut in finish turning yields a surface roughness of Ra 0.25 µm consistently. For drilling operations, pecking cycles are recommended for depths exceeding 3× diameter to ensure chip evacuation.

Corrosion Resistance

C36000 performs excellently in the following environments:

• Atmospheric Environment: Excellent atmospheric corrosion resistance, with a corrosion rate of less than 0.0025 mm/year in industrial atmospheres
• Fresh Water: Suitable for fresh water environments, with negligible corrosion up to 60°C; maximum recommended velocity of 2 m/s to avoid erosion
• Seawater: Good seawater corrosion resistance, though dezincification may occur in stagnant conditions; use inhibited grades for critical marine applications; corrosion rate typically 0.01-0.05 mm/year in flowing seawater
• Acids and Alkalis: General corrosion resistance in dilute acids (pH 4-6) and alkalis (pH 8-10); avoid concentrated sulfuric or nitric acids; maximum temperature for dilute acids is 50°C
• Stress Corrosion Cracking: Susceptible in ammonia-containing environments; stress-relief annealing at 250°C for 1 hour reduces risk; threshold stress for SCC is approximately 200 MPa in ammonia atmospheres
• Organic Compounds: Excellent resistance to hydrocarbons, alcohols, and most organic solvents up to 100°C

5. Typical Applications

• Electrical Industry: Conductive parts, connectors, terminals, and switch components requiring high machinability and moderate conductivity; typical applications include relay components and fuse holders
• Shipbuilding: Propellers, valves, pump components, and marine hardware where corrosion resistance and machinability are critical; used in seawater piping systems up to 30°C
• Watch Parts: Precision components such as gears, pinions, and balance wheels requiring tight tolerances of ±0.005 mm and smooth finishes down to Ra 0.1 µm
• Lock Hardware: Lock cylinders, keys, and security mechanisms benefiting from wear resistance and machinability; typical hardness of 80 HRB ensures durability
• CNC Machining Parts: Precision parts for automotive, aerospace, and medical devices, including fittings, adapters, and decorative items; typical batch sizes range from 100 to 50,000 pieces
• Hydraulic Components: Valve bodies, connectors, and manifolds requiring leak-tight seals and complex internal geometries; pressure ratings up to 350 bar in hydraulic systems
• Automotive: Fuel system components, carburetor parts, and sensor housings where machinability and corrosion resistance are essential
• Plumbing: Faucet components, valve stems, and pipe fittings requiring excellent machinability for high-volume production

6. Why Choose Dongguan Stirling Metal Products Co., Ltd.

Dongguan Stirling Metal Products Co., Ltd. specializes in providing C36000 material + CNC Machining One-Stop Service, backed by over 15 years of experience in precision machining. Our facility houses 50+ CNC lathes and milling machines, including 5-axis capabilities, enabling us to produce complex geometries with tolerances down to ±0.005 mm. We maintain a 500-ton inventory of C36000 in various forms (round bars, hex bars, sheets, and custom extrusions) sourced directly from ASTM-certified mills. Our quality system includes real-time SPC monitoring on all critical dimensions, with Cpk values consistently above 1.33 for tight tolerance features.

• ✅ Material Procurement: Genuine product guarantee with complete MTC (Mill Test Certificate) traceable to the original heat number; we stock diameters from 3 mm to 100 mm in round bars
• ✅ CNC Machining: Accuracy ±0.01 mm standard, ±0.005 mm for critical features; surface finish down to Ra 0.2 µm; we achieve 99.8% first-pass yield on complex parts
• ✅ Sample Making: Fast delivery in 3-5 days for prototypes, with free DFM (Design for Manufacturing) feedback; we provide 3D inspection reports for all samples
• ✅ Batch Production: Delivery in 7-15 days for orders up to 10,000 pieces; 100% inspection for critical dimensions using CMM and optical measurement systems
• ✅ Surface Treatment: Polishing, electroplating (nickel, chrome, gold), passivation, and powder coating in-house; we offer RoHS-compliant finishes
• ✅ Quality Assurance: ISO 9001:2015 certified; CMM inspection reports provided with every shipment; we perform 100% dimensional inspection on first articles
• ✅ Engineering Support: Our team of 10 senior engineers provides design optimization for machinability, reducing cycle times by up to 20% on average

For a Free Quote, please Contact Us! Our engineering team will review your drawings and provide optimized machining parameters within 24 hours. We offer competitive pricing for volumes from 100 to 100,000 pieces, with lead times as short as 5 working days for standard parts.