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China Bronze CNC Machining: Leading Suppliers and Factory for High-Quality Industrial Parts
Bronze typically refers to a family of alloys with copper as the base, primarily alloyed with elements such as tin, aluminum, silicon, and manganese. Compared to brass (copper-zinc alloys), bronze generally offers higher strength, a lower coefficient of friction, and better chemical corrosion resistance (especially against seawater). Its outstanding wear resistance and self-lubricating properties make it irreplaceable in bearing and bushing applications.
1. C93200 / SAE 660 — High-Leaded Tin Bronze (Bearing Bronze)
- ⚙️ Characteristics: This is the most widely used bearing bronze. The added lead forms soft particles within the alloy, providing excellent self-lubricating and anti-galling properties, making it ideal for operation under insufficient lubrication or high-load, low-speed conditions. It is easy to machine and offers good wear resistance.
- 🔩 Typical Applications: General-purpose bearings, bushings, thrust washers, pump components, low-load gears.
C93200 Typical Properties (As Sand-Cast)
| Property | Value | Notes |
| Tensile Strength (MPa) | 240 – 330 | Good overall strength |
| Yield Strength (0.5% Extension, MPa) | 124 | |
| Elongation at Break (%) | 18 | Good ductility |
| Hardness (Brinell) | 65 | |
| Density (g/cm³) | 8.93 | |
| Key Composition | Cu-83%, Sn-7%, Pb-7%, Zn-3% | High lead content provides self-lubrication |
Note: Values are typical ranges, specific to casting and processing conditions.
2. C95400 — Aluminum Bronze
- ⚙️ Characteristics: A high-strength, high-hardness aluminum bronze. Its corrosion resistance, wear resistance, and fatigue strength are among the best of all bronzes, with performance comparable to many steels. It retains strength at elevated temperatures and offers excellent impact and cavitation resistance.
- 🔩 Typical Applications: Heavy-duty bearings, gears, valve seats, pump housings, propellers and components for seawater use, chemical processing equipment.
C95400 Typical Properties (Heat-Treated Condition)
| Property | Value | Notes |
| Tensile Strength (MPa) | 620 – 760 | Very high strength, comparable to low-alloy steels |
| Yield Strength (0.2% Offset, MPa) | 275 | |
| Elongation at Break (%) | 12 – 18 | |
| Hardness (Brinell) | 170 – 210 | High hardness, very wear-resistant |
| Density (g/cm³) | 7.45 | Lighter than tin bronze |
| Key Composition | Cu-85%, Al-11%, Fe-4% | Tin-free, uses aluminum and iron as main alloying elements |
Note: Values are typical ranges, specific to heat treatment condition.
3. C54400 — Phosphor Bronze
- ⚙️ Characteristics: A tin bronze containing a small amount of phosphorus. Phosphorus increases the alloy's elastic limit, fatigue strength, and wear resistance. This material offers excellent spring properties, good wear and corrosion resistance, and is easily machined into precision parts.
- 🔩 Typical Applications: Electrical connectors, springs, diaphragms, bellows, wear plates, precision gears.
C54400 Typical Properties (Cold Worked Condition)
| Property | Value | Notes |
| Tensile Strength (MPa) | 520 – 690 | High strength, especially suitable for elastic elements |
| Yield Strength (0.2% Offset, MPa) | 380 – 550 | High yield strength |
| Elongation at Break (%) | 10 – 15 | |
| Hardness (Rockwell B) | 78 – 90 | |
| Density (g/cm³) | 8.8 | |
| Key Composition | Cu-88%, Sn-4%, Zn-4%, P-0.2–0.5% | Phosphorus acts as a deoxidizer and enhances properties |
Note: Values are typical ranges, specific to the degree of cold work.
4. C65500 — High-Silicon Bronze
- ⚙️ Characteristics: A bronze with excellent corrosion resistance, particularly outstanding in sulfuric acid and sulfate environments. It combines high strength, high corrosion resistance, and good formability and weldability, making it widely used in chemical and marine industries.
- 🔩 Typical Applications: Chemical processing equipment components, heat exchanger tube sheets, marine fittings, pump valves, fasteners, welded structures.
❓ Frequently Asked Questions
Q
What is the main difference between C93200 and C95400 bronze?
C93200 (SAE 660) is a high-leaded tin bronze optimized for self-lubrication and anti-galling performance under low-speed, high-load conditions, making it the go-to choice for general-purpose bearings. C95400 is an aluminum bronze with significantly higher tensile strength (620–760 MPa vs. 240–330 MPa), superior hardness, and better resistance to corrosion and cavitation, making it suitable for heavy-duty and marine applications.
Q
Why is lead added to C93200 bearing bronze?
Lead forms soft, discrete particles within the copper-tin matrix. These particles act as a built-in solid lubricant, reducing friction and preventing metal-to-metal galling when oil film lubrication is insufficient. This makes C93200 particularly reliable in intermittent or boundary lubrication conditions.
Q
What role does phosphorus play in C54400 phosphor bronze?
Phosphorus serves two key functions in C54400: it acts as a deoxidizer during casting, improving the soundness and density of the alloy, and it significantly enhances the elastic limit, fatigue strength, and wear resistance. These properties make phosphor bronze ideal for springs, electrical connectors, and precision wear components.
Q
Is C95400 aluminum bronze suitable for seawater environments?
Yes. C95400 aluminum bronze offers excellent resistance to seawater corrosion, biofouling, and cavitation erosion. Its high strength and corrosion resistance make it a preferred material for marine propellers, pump housings, valve components, and other offshore or underwater applications.
Q
How does C65500 high-silicon bronze compare to other bronzes in terms of weldability?
C65500 stands out among bronze alloys for its excellent weldability and formability. While most bronzes are difficult to weld due to hot cracking or porosity issues, the silicon content in C65500 improves fluidity and reduces oxidation during welding, making it well-suited for fabricated and welded structural components in chemical and marine industries.
Q
How do I choose the right bronze alloy grade for my application?
Selection depends on your primary requirements: C93200 is best for general bearings and bushings needing self-lubrication; C95400 suits heavy-duty, high-strength, or marine applications; C54400 is ideal for precision elastic components like springs and connectors; and C65500 excels in corrosive chemical or welded structural environments. Consider load, speed, lubrication availability, environmental exposure, and machinability requirements when making your choice.
Finishes and Post-Processing Options
The zinc alloy substrate is highly suitable for various surface treatments to enhance decoration, protection, or functionality:
Electroplating: Such as chrome, nickel, gold, or silver plating, providing a highly decorative appearance, excellent wear and corrosion resistance. This is the most common choice.
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Passivation or Chromate Conversion Coating:
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Powder Coating:
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Painting:
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Physical Vapor Deposition (PVD):
Design and Machining Considerations
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Process Selection:
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Design Considerations:
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Material Selection:
Zamak 3 and 5 are suitable for the vast majority of general-purpose parts requiring good appearance and strength; ZA-8 is better for wear and bearing applications; for making rapid tooling, choose specialized alloys like Kirksite.
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