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High-Precision Bronze CNC Machining Services by China Factory & Suppliers for Durable Industrial Components
Common Bronze Alloy Grades and Characteristics
Bronze generally refers to a group of copper‑based alloys, mainly alloyed with tin, aluminum, silicon, manganese, and other elements. Compared with brass (copper‑zinc alloys), bronze typically features higher strength, a lower friction coefficient, and better chemical corrosion resistance—especially in seawater environments. Thanks to its excellent wear resistance and self‑lubricating properties, it plays an irreplaceable role in bearings and bushings. Our machining centers are well‑equipped to process various bronze materials, supporting high‑quality production from complex prototypes to small‑batch manufacturing.
1. C93200 / SAE 660 (High-Leaded Tin Bronze - Bearing Bronze)
Characteristics: This is the most commonly used bearing bronze grade. Lead is added to form soft particles in the alloy structure, delivering exceptional self-lubrication and anti-galling performance. This makes it particularly suitable for applications with insufficient lubrication, or under high-load and low-speed operating conditions. It features good machinability and reliable wear resistance.
Typical Applications: Suitable for general‑purpose bearings, bushings, thrust washers, pump components, and low‑load gears across various industrial applications.
| 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: This is a high‑strength, high‑hardness aluminum bronze. It boasts some of the best corrosion resistance, wear resistance, and fatigue strength among all bronze alloys, with performance comparable to many steel materials. It maintains its strength at elevated temperatures and delivers excellent resistance to impact and cavitation.
Typical Applications: Ideal for heavy-duty bearings, gears, valve seats, pump housings, marine propellers and seawater-resistant components, as well as various parts used in chemical processing equipment.
| 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: This is a tin bronze with a small addition of phosphorus. Phosphorus enhances the alloy’s elastic limit, fatigue strength, and wear resistance. The material exhibits excellent spring characteristics, good wear and corrosion resistance, and can be readily machined into precision components.
Typical Applications: Perfect for electrical connectors, springs, diaphragms, bellows, wear plates, and high-precision gears across multiple industrial applications.
| 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: This bronze features exceptional corrosion resistance, especially in sulfuric acid and sulfate environments. It combines high strength, excellent corrosion resistance, good formability and weldability, making it widely applied in the chemical and marine industries.
Typical Applications: Ideal for components in chemical processing equipment, heat exchanger tube sheets, marine hardware and fittings, pump and valve parts, fasteners, as well as welded structural parts.
Frequently Asked Questions (FAQ)
Q: What makes C93200 (SAE 660) suitable for bearing applications?
C93200 contains a high lead content (approx. 7%), which forms soft particles in the alloy. This provides exceptional self-lubricating properties and anti-galling performance, making it ideal for bearings operating under high loads and low speeds where lubrication may be insufficient.
Q: How does C95400 Aluminum Bronze compare to steel?
C95400 is a high-strength aluminum bronze with mechanical properties comparable to many low-alloy steels. It offers tensile strengths of 620-760 MPa along with superior corrosion resistance, wear resistance, and impact strength, making it a lighter, rust-resistant alternative to steel in heavy-duty applications.
Q: Why is phosphorus added to C54400 Phosphor Bronze?
A small addition of phosphorus (0.2-0.5%) acts as a deoxidizer during melting. It significantly enhances the alloy's elastic limit, fatigue strength, and wear resistance, which is why C54400 is widely used for electrical connectors, springs, and diaphragms.
Q: Which bronze grade is best for chemical and marine environments?
C65500 High-Silicon Bronze offers exceptional corrosion resistance, particularly in sulfuric acid, sulfate environments, and seawater. C95400 Aluminum Bronze is also highly resistant to seawater corrosion and cavitation, making both grades excellent choices for marine hardware and chemical equipment.
Q: Can these bronze alloys be welded easily?
C65500 High-Silicon Bronze exhibits excellent weldability and formability, making it ideal for welded structural parts. In contrast, leaded bronzes like C93200 are difficult to weld due to the risk of lead sweating and hot cracking, and are typically joined by brazing or mechanical fastening.
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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