C11000 copper, also known as electrolytic tough pitch (ETP) copper, is the industry benchmark for electrical and thermal conductivity applications. With a minimum copper content of 99.90% and an electrical conductivity rating of 101% IACS (International Annealed Copper Standard), this material is the preferred choice for high-performance electrical components, heat exchangers, and precision CNC machined parts. Its exceptional combination of conductivity, ductility, and corrosion resistance makes it indispensable in industries ranging from power generation to aerospace. At Dongguan Stirling Metal Products Co., Ltd., we specialize in precision CNC machining of C11000 copper, delivering components with tolerances as tight as ±0.005 mm and surface finishes down to Ra 0.4 µm. The material’s unique properties, including a thermal conductivity of 401 W/m·K and a density of 8.94 g/cm³, enable engineers to design systems that maximize energy efficiency and heat dissipation, critical for modern electronics and renewable energy applications.
1. C11000 Basic Information
C11000 is a commercially pure copper alloy (UNS designation C11000) with a nominal copper content of 99.90% minimum. It is produced by electrolytic refining and is characterized by its high electrical and thermal conductivity, excellent formability, and good corrosion resistance. The material is available in various forms including sheet, plate, rod, bar, tube, and wire, making it suitable for a wide range of CNC machining applications. Its density of 8.94 g/cm³ and melting point of 1083°C provide a robust foundation for high-precision machining operations. The oxygen content, typically between 0.02% and 0.04%, is carefully controlled to optimize conductivity while minimizing hydrogen embrittlement during welding or brazing. C11000 is non-magnetic with a magnetic permeability of 1.0 µ, making it ideal for sensitive electronic and medical applications. The material’s electrical resistivity at 20°C is 1.724 × 10⁻⁸ Ω·m, which is the lowest among all commercial copper alloys, ensuring minimal power losses in electrical systems.
2. Chemical Composition
The chemical composition of C11000 copper is tightly controlled to ensure consistent performance. The following table provides the standard composition ranges as per ASTM B152/B152M and ASTM B187/B187M specifications:
| Element | Content (%) | Specification |
|---|---|---|
| Copper (Cu) + Silver (Ag) | 99.90 min | ASTM B152 |
| Oxygen (O) | 0.02 – 0.04 | Controlled for conductivity |
| Iron (Fe) | ≤ 0.005 | Impurity limit |
| Lead (Pb) | ≤ 0.005 | Impurity limit |
| Bismuth (Bi) | ≤ 0.001 | Impurity limit |
| Antimony (Sb) | ≤ 0.002 | Impurity limit |
| Arsenic (As) | ≤ 0.002 | Impurity limit |
| Nickel (Ni) | ≤ 0.002 | Impurity limit |
| Tellurium (Te) | ≤ 0.001 | Impurity limit |
| Selenium (Se) | ≤ 0.001 | Impurity limit |
| Silver (Ag) | 0.02 – 0.05 | Typical for conductivity |
The oxygen content in C11000 is deliberately maintained between 0.02% and 0.04% to optimize electrical conductivity while minimizing hydrogen embrittlement during welding or brazing operations. The high purity ensures that the material achieves 101% IACS conductivity at 20°C. Trace elements like iron, lead, and bismuth are kept below 0.005% each to prevent degradation of electrical properties. The silver content, typically 0.02-0.05%, enhances conductivity and provides a slight improvement in creep resistance at elevated temperatures. This precise composition ensures that C11000 meets the stringent requirements of ASTM B152 for sheet and plate, and ASTM B187 for rod and bar, with a guaranteed minimum copper content of 99.90%.
3. Mechanical & Physical Properties
C11000 copper exhibits a unique combination of mechanical strength and physical properties that make it ideal for CNC machining. The following tables provide comprehensive data for typical tempers:
| Property | Value (Annealed) | Value (Half-Hard) | Unit |
|---|---|---|---|
| Tensile Strength | 220 – 260 | 310 – 380 | MPa |
| Yield Strength (0.2% offset) | 70 – 90 | 250 – 300 | MPa |
| Elongation (in 50 mm) | 45 – 55 | 10 – 20 | % |
| Hardness (Rockwell F) | 45 – 55 | 75 – 85 | HRF |
| Hardness (Vickers) | 80 – 100 | 120 – 140 | HV |
| Modulus of Elasticity | 117 | 117 | GPa |
| Poisson’s Ratio | 0.34 | 0.34 | – |
| Physical Property | Value | Unit |
|---|---|---|
| Density | 8.94 | g/cm³ |
| Electrical Conductivity (at 20°C) | 101 | % IACS |
| Electrical Resistivity (at 20°C) | 1.724 × 10⁻⁸ | Ω·m |
| Thermal Conductivity (at 20°C) | 401 | W/m·K |
| Thermal Expansion Coefficient (20-100°C) | 17.0 × 10⁻⁶ | /°C |
| Specific Heat Capacity (at 20°C) | 385 | J/kg·K |
| Melting Point (Liquidus) | 1083 | °C |
| Melting Point (Solidus) | 1065 | °C |
| Magnetic Permeability | 1.0 (Non-magnetic) | µ |
The electrical conductivity of 101% IACS is the highest among all commercial copper alloys, making C11000 the standard for bus bars, connectors, and windings. Its thermal conductivity of 401 W/m·K is nearly double that of aluminum (237 W/m·K), enabling rapid heat dissipation in CNC machining operations. The modulus of elasticity of 117 GPa provides good stiffness for precision components, while the elongation of 45-55% in the annealed condition ensures excellent formability for complex geometries. The thermal expansion coefficient of 17.0 × 10⁻⁶ /°C is moderate, requiring careful consideration in applications with large temperature variations, such as power electronics or heat exchangers.
4. Corrosion Resistance
C11000 copper exhibits excellent corrosion resistance in a variety of environments due to the formation of a protective patina layer (basic copper carbonate). The following data summarizes its performance:
- Atmospheric Environment: Excellent resistance; corrosion rate < 0.1 µm/year in rural and industrial atmospheres. In marine environments, rate increases to 0.5-1.0 µm/year.
- Fresh Water: Corrosion rate < 0.05 mm/year in potable water (pH 6.5-8.5). Suitable for plumbing and heat exchanger tubes.
- Seawater: Good resistance with corrosion rates of 0.02-0.05 mm/year in stagnant conditions. In flowing seawater (1-2 m/s), rate increases to 0.1-0.3 mm/year.
- Acids and Alkalis: Resistant to non-oxidizing acids (e.g., hydrochloric acid up to 10% concentration at room temperature). Not recommended for oxidizing acids (e.g., nitric acid) or strong alkalis (pH > 12).
- Soil: Corrosion rate of 0.2-0.5 µm/year in neutral soils; higher in acidic or alkaline soils.
For CNC machined parts, the corrosion resistance can be enhanced through surface treatments such as electropolishing (achieving Ra < 0.2 µm) or chromate conversion coating (MIL-C-5541). In marine environments, the addition of a protective coating or cathodic protection can extend service life. The material's resistance to biofouling in seawater makes it ideal for heat exchanger tubes in desalination plants and shipboard systems. In potable water systems, C11000 meets NSF/ANSI 61 standards for drinking water components, ensuring safe and long-lasting performance.
5. CNC Machining Performance
C11000 copper is classified as a free-machining material with a machinability rating of 20% (relative to C36000 brass at 100%). However, its high thermal conductivity (401 W/m·K) requires careful management of cutting parameters to prevent tool overheating. The following table provides optimized CNC machining parameters for various operations:
| Operation | Cutting Speed (m/min) | Feed Rate (mm/rev) | Depth of Cut (mm) | Tool Material | Coolant |
|---|---|---|---|---|---|
| Turning (Roughing) | 150 – 250 | 0.15 – 0.30 | 2.0 – 4.0 | Carbide (K10/K20) | Water-soluble emulsion |
| Turning (Finishing) | 200 – 300 | 0.05 – 0.15 | 0.2 – 0.5 | Carbide (K10) or PCD | Mist or flood |
| Milling (Roughing) | 100 – 200 | 0.10 – 0.25 (mm/tooth) | 1.0 – 3.0 | Carbide (K20/K30) | Flood coolant |
| Milling (Finishing) | 150 – 250 | 0.05 – 0.10 (mm/tooth) | 0.1 – 0.3 | Carbide (K10) or PCD | Mist or flood |
| Drilling (HSS) | 30 – 60 | 0.05 – 0.15 | N/A | HSS-Co or Carbide | Flood coolant |
| Drilling (Carbide) | 80 – 150 | 0.08 – 0.20 | N/A | Carbide (K20) | Flood coolant |
| Threading | 50 – 100 | 0.05 – 0.10 | 0.1 – 0.3 | Carbide (K10) | Oil-based coolant |
Key machining considerations for C11000 copper include:
- Chip Control: Copper produces long, stringy chips. Use chip breakers or peck drilling cycles to prevent chip entanglement. For turning, use a chip breaker geometry with a positive rake angle of 10°-15°.
- Tool Wear: High thermal conductivity causes rapid heat transfer to the tool, leading to edge buildup. Use sharp tools with positive rake angles (10°-15°) and TiN or TiAlN coatings. PCD tools are recommended for finishing operations to achieve surface finishes below Ra 0.2 µm.
- Surface Finish: Achievable Ra values of 0.4-0.8 µm with carbide tools and 0.1-0.2 µm with PCD tools. For mirror finishes, use diamond turning with cutting speeds > 500 m/min and a feed rate of 0.02-0.05 mm/rev.
- Coolant: Flood coolant is essential for heat dissipation. Water-soluble emulsions at 5-10% concentration are recommended. For high-speed operations, use high-pressure coolant (20-40 bar) to improve chip evacuation and tool life.
- Workholding: Use soft jaws or vacuum chucks to avoid marring the surface. For thin-walled parts, consider using a steady rest or tailstock to minimize vibration and deflection.
- Tool Life: Carbide tools typically achieve 30-60 minutes of cutting time before needing replacement. PCD tools can last 200-400 minutes, making them cost-effective for high-volume production.
6. Typical Applications
C11000 copper is used in a wide range of industries due to its superior electrical and thermal properties. Key applications include:
- Electrical Industry: Bus bars (up to 5000 A capacity), connectors, terminals, switchgear components, and transformer windings. Conductivity ensures minimal I²R losses, with typical resistance of 0.01724 Ω·mm²/m at 20°C.
- Heat Exchangers: Radiator cores, condenser tubes, and heat sinks for power electronics. Thermal conductivity of 401 W/m·K enables efficient heat transfer, with a heat transfer coefficient of 500-1000 W/m²·K in typical applications.
- Automotive: Battery terminals, alternator windings, and starter motor components. Used in electric vehicle (EV) battery packs for bus bars and cooling plates, where conductivity reduces energy losses by up to 15% compared to aluminum.
- Aerospace: Waveguides, antenna components, and thermal management systems. Non-magnetic properties are critical for sensitive electronics, with a magnetic permeability of 1.0 µ ensuring no interference.
- CNC Machining Parts: Precision components such as bushings, bearings, nozzles, and valve seats. Tolerances of ±0.01 mm are achievable with our advanced 5-axis machining centers, with surface finishes down to Ra 0.2 µm.
- Marine: Propeller shafts, seawater piping, and heat exchanger tubes. Corrosion resistance in seawater ensures long service life, with a typical lifespan of 20-30 years in marine environments.
- Medical: MRI components, surgical instruments, and implantable devices. Biocompatibility and non-magnetic nature are advantageous, with C11000 meeting ISO 10993 standards for medical devices.
7. Why Choose Dongguan Stirling Metal Products Co., Ltd.
Dongguan Stirling Metal Products Co., Ltd. is a leading provider of precision CNC machining services for C11000 copper and other high-performance alloys. Our capabilities include:
- Material Expertise: We source C11000 copper from certified mills with full MTC (Mill Test Certificate) traceability. All material meets ASTM B152, B187, and B133 standards, with a minimum copper content of 99.90% and conductivity of 101% IACS.
- CNC Machining: Our facility is equipped with 30+ CNC machines including 5-axis machining centers, Swiss-type lathes, and multi-spindle automatics. We achieve tolerances as tight as ±0.005 mm and surface finishes down to Ra 0.2 µm, with a Cpk of ≥1.67 for critical features.
- Quality Control: We use Zeiss CMM (Coordinate Measuring Machine) for dimensional inspection, with a measurement accuracy of ±0.001 mm. Our ISO 9001:2015 certified quality system ensures consistent output, with a defect rate of less than 50 ppm.
- Surface Treatment: In-house capabilities include electropolishing (Ra < 0.1 µm), passivation (ASTM A967), and plating (silver, nickel, gold). We also offer anodizing and chromate conversion coating for enhanced corrosion resistance.
- Lead Times: Prototype samples in 3-5 days, production orders in 7-15 days. We offer JIT (Just-In-Time) delivery for high-volume programs, with a 98% on-time delivery rate.
- Cost Efficiency: Our optimized machining parameters reduce cycle times by up to 20% compared to industry averages, translating to lower per-part costs. For high-volume runs, we offer volume discounts of up to 15%.
For a Free Quote, please Contact Us! Our engineering team will provide a detailed DFM (Design for Manufacturability) analysis within 24 hours, including toolpath optimization, material utilization, and cost breakdown. We are committed to delivering high-quality C11000 copper components that meet your exact specifications, with a focus on precision, reliability, and cost-effectiveness.
