Copper materials occupy a unique niche in the realm of precision parts—while not as mainstream as aluminum alloys, they are absolutely indispensable in specific applications. Excellent electrical and thermal conductivity, combined with strong corrosion resistance, are the primary reasons for selecting copper materials.
However, “copper” is not a single material. Brass (Cu-Zn alloy), beryllium copper (Cu-Be alloy), and red copper (pure copper) differ vastly in performance and price—with cost variations of five to ten-fold—and possess completely different machining characteristics. Choosing the wrong material can lead to anything from unnecessary expense to functional failure.
This article provides a systematic comparison across four dimensions—material properties, machining characteristics, application scenarios, and cost—to help engineers make the right choice of copper material before finalizing their drawings.
I. Comparison of Basic Parameters for the Three Copper Materials
Let’s look at the key data:
Several critical comparisons:
Beryllium copper boasts a strength two to three times that of brass and four to five times that of pure copper, approaching the strength of medium-strength steel. This explains why it costs 15 to 25 times more than the others and highlights its core value proposition.
Pure copper has an electrical conductivity of 100% IACS (International Annealed Copper Standard; the conductivity of other materials is rated relative to pure copper) and a thermal conductivity of 390–400 W/(m·K)—the highest among the three. In contrast, the electrical conductivity of brass and beryllium copper is only 25% and 20% of that of pure copper, respectively.
Brass offers the best machinability of the three. C3604 is a grade specifically designed for free-cutting applications; containing 2%–3% lead, it produces short, brittle chips and causes minimal tool wear, making it one of the easiest metal materials to machine.
II. Brass (C3604/HPb59-1)
C3604 is a globally recognized free-cutting brass, while HPb59-1 is the corresponding Chinese national standard (GB) grade; together, they represent the most widely used copper materials in precision parts manufacturing. Why it is easy to machine:
The zinc content (35%–40%) in brass transforms the copper alloy from a single-phase FCC structure to a dual-phase α+β structure. Additionally, the inclusion of lead (2%–3%) creates finely dispersed lead particles that act as chip breakers and lubricants during the cutting process. This results in short, brittle chips, a smooth machined surface, and minimal tool wear.
Reference parameters for CNC machining of brass (finishing):
Cutting speed: 200–600 m/min (suitable for high-speed machining)
Feed rate: 0.05–0.2 mm/rev
Depth of cut: 0.1–0.5 mm
Cutting tool: Uncoated carbide or TiN-coated carbide
Cooling: Emulsion coolant; dry machining is also possible (for short durations)
Surface roughness: Ra 0.4–0.8 μm achievable in finishing
Machining cost (lowest among copper alloys):
Compared to 6061 aluminum alloy, brass has a slightly lower cutting speed and requires approximately 30%–50% more machining time; however, it remains one of the easiest metals to machine. The total cost (material + processing) is typically 1.5 to 2 times that of aluminum alloy. Key Application Scenarios:
Precision threaded parts: Brass offers high thread precision and is less prone to stripping (cross-threading) than aluminum alloys.
Precision fittings (hardware): Connector housings, joints, valve bodies.
Conductive connectors (moderate conductivity requirements): Conductivity is 25–28% IACS; not suitable for high-conductivity applications.
Precision gears: Brass gears operate quietly and are non-magnetic.
Measuring instrument parts: Brass offers good stability and is non-magnetic.
Applications unsuitable for brass:
High conductivity requirements (pure copper is required).
High strength requirements (beryllium copper is required).
Contact with drinking water (brass contains lead and does not meet drinking water safety standards; lead-free brass or other materials must be used).
III. Beryllium Copper (C17200/QBe2)
Beryllium copper is a copper alloy with unique performance characteristics—its strength approaches that of steel while retaining the conductivity and elasticity of copper; no other metal material possesses all three of these properties simultaneously.
Source of strength in beryllium copper:
After beryllium (Be) forms a solid solution in copper, solution-aging treatment causes the precipitation of fine CuBe phases, resulting in a significant precipitation hardening effect. Following aging treatment, hardness increases from an initial 100–150 HB to 280–400 HB, and strength rises from 250–400 MPa to 1000–1380 MPa.
Two states of beryllium copper:
Solution-treated state (soft state, C17200-A):
Hardness is approximately 100–150 HB, and tensile strength is approximately 400–500 MPa; machinability is relatively good (comparable to standard copper alloys). Precision parts are typically machined in the solution-treated state and then age-hardened to achieve final hardness.
Age-hardened state (hard state, C17200-HT):
Hardness is 280–400 HB, and tensile strength is 1000–1380 MPa. Machining is extremely difficult, and tool wear is rapid; precision features are generally not machined after aging—only light operations like deburring are performed. Machining Precautions (Safety Warning):
Beryllium is a toxic metal; the OSHA Permissible Exposure Limit (PEL) for beryllium dust and fumes is 0.2 μg/m³ (a very low level). When machining beryllium copper, wet cutting is mandatory (dry cutting is prohibited to prevent the spread of beryllium dust), dust masks must be worn, and chips and waste fluids must be disposed of as hazardous waste. These are mandatory safety requirements for machining beryllium copper and cannot be bypassed.
Beryllium Copper CNC Machining Parameters (Finishing in Solution-Treated State):
Cutting speed: 100–250 m/min
Feed rate: 0.05–0.1 mm/rev
Cutting tool: Carbide (High-speed steel is not recommended due to rapid wear)
Cooling: Cutting fluid is mandatory (wet cutting to prevent beryllium dust)
Key Application Scenarios:
Elastic components: Beryllium copper contact springs, coil springs, and contact strips—beryllium copper is the optimal metal material for elastic components (simultaneously satisfying the three requirements of high elastic modulus, high strength, and good electrical conductivity).
Elastic contacts for electrical connectors: Widely used in mobile phone SIM card slot springs and USB interface contact springs.
Elastic sensing elements for precision instruments: Force sensor elastic bodies, torque sensors.
Non-sparking tools (explosion-proof applications): Beryllium copper does not produce sparks, making it suitable for tools used in hazardous environments.
High-precision mold components: Utilizes beryllium copper’s high thermal conductivity and strength for injection mold inserts, offering high cooling efficiency.
Price Note:
Raw beryllium copper costs approximately 800–1,500 RMB/kg, which is 15–25 times the price of brass and 20–35 times that of aluminum alloy. The choice of beryllium copper must be driven by a mandatory functional requirement (simultaneous need for elasticity, strength, and conductivity); it should not be selected arbitrarily simply because “beryllium copper has good properties.”
IV. Pure Copper (Red Copper, T2/T1)
T2 is the most commonly used grade of pure copper for precision part machining; it has a copper content of ≥99.9% and offers the highest electrical and thermal conductivity among all copper materials. Electrical and Thermal Conductivity:
Pure copper has an electrical conductivity of 100% IACS (the defined benchmark) and a thermal conductivity of 390–400 W/(m·K)—approximately 2.4 times that of aluminum alloys and 25 times that of stainless steel. It is the only choice for applications requiring exceptional electrical or thermal conductivity.
Machining Challenges (The Most Difficult of the Three):
Pure copper possesses excellent ductility (elongation at break ≥35%); during machining, the chips are tough and prone to adhering to the cutting tool (forming built-up edges), while the machined surface is susceptible to burrs that are difficult to remove. Solutions:
Tools must be extremely sharp (large rake angle, large clearance angle, and absolutely no burrs or rolled edges on the cutting edge).
High cutting speed (to minimize the time available for built-up edge formation): 300–500 m/min for finishing.
Adequate cooling and lubrication (emulsion or cutting oil).
Moderate feed rate (to reduce cutting force per pass and minimize material adhesion to the tool).
Small finishing allowance (0.05–0.1 mm per side); large allowances exacerbate deformation and adhesion issues.
Pure Copper CNC Machining Parameters (Finishing):
Cutting speed: 200–500 m/min
Feed rate: 0.03–0.08 mm/rev (lower than for brass)
Tooling: Sharp carbide tools with a rake angle ≥10°; coated tools are not recommended (coatings reduce sharpness).
Cooling: Ample emulsion cooling.
Surface roughness: Ra 0.8–1.6 μm for finishing; achieving low roughness is more difficult than with brass.
Key Application Scenarios:
Conductive busbars and terminals: Pure copper is the only choice for high-current conduction.
Heat dissipation components (copper heat sinks/blocks): Heat dissipation bases for high-power devices; thermal conductivity of 400 W/(m·K).
EDM electrodes (copper electrodes): Tool electrodes for Electrical Discharge Machining; pure copper offers stable discharge and low electrode wear, making it the preferred material.
Welding tips: Welding torch tips and spot welding electrodes; requires high thermal and electrical conductivity.
High-frequency shielding components: Pure copper offers high electrical conductivity and excellent shielding performance.
Internal vacuum device components: Ultra-pure copper is used in vacuum environments requiring extremely low outgassing.
V. Comprehensive Quick-Reference Table for Three Copper Materials
VI. Material Selection Decision Process
Q1: Is extremely high electrical conductivity (>80% IACS) or extremely high thermal conductivity (>300 W/(m·K)) required? → Yes → Pure Copper T2 (the only choice)
→ No → Q2
Q2: Does the part require both elasticity and strength, or is it an elastic component (such as a contact strip or spring)?
→ Yes → Beryllium Copper C17200 (age-hardened; irreplaceable)
→ No → Q3
Q3: Is high strength (>600 MPa) required, and must the material be copper?
→ Yes → Beryllium Copper C17200
→ No → Q4
Q4: Are there explosion-proof or non-sparking requirements?
→ Yes → Beryllium Copper C17200
→ No → Brass C3604 (best machinability, lowest cost; meets the vast majority of copper part requirements)
Kzron specializes in the precision machining of a full range of copper alloy parts—including Brass (C3604/HPb59-1), Beryllium Copper (C17200/QBe2), and Pure Copper (T1/T2). We have no minimum order quantity (MOQ) requirements, offer a 5–10 day delivery time for small batches, guarantee precision to ±0.01mm, and are ISO9001:2015 certified.
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