Aluminium Bronze CA104 Bushing
Aluminium Bronze CA104 Bushing
Self-lubricating bronze bearings are engineered for applications where external lubrication is impractical. Solid lubricants are compressed and molded directly into the bearing to guarantee a maintenance-free product. No additional lubrication is necessary.
Aluminium Bronze CA104 Bushing | High Strength & Wear Resistant
In the demanding world of heavy engineering, marine applications, and high-load machinery, the choice of material for critical components like bushings and bearings is paramount. It is a decision that directly impacts equipment lifespan, maintenance costs, and operational reliability. Among the vast family of copper alloys, Aluminium Bronze CA104 (also known as BS B23 or CW307G) stands out as the "Special Forces" of copper alloys, offering a combination of mechanical strength and corrosion resistance that few materials can match.
The Engineering Imperative: Why Choose CA104?
Aluminium Bronze CA104 is a high-strength, wrought Nickel-Aluminium Bronze alloy. Its formal designation under the British Standard is BS B23, and it is closely related to the American UNS C63200 and C63000 specifications. The selection of CA104 over more common materials like Phosphor Bronze or Leaded Gunmetal is driven by a set of core engineering advantages:
- Exceptional Mechanical Strength: CA104 possesses a tensile strength comparable to that of medium-carbon steel, allowing it to withstand extremely high impact loads and heavy static or dynamic stresses .
- Superior Corrosion Resistance: The alloy's high aluminium content (typically 8.5% to 11.0%) facilitates the formation of a dense, self-healing Aluminium Oxide ($text_2text_3$) protective film on its surface. This passive layer provides outstanding resistance to corrosion in harsh media, particularly seawater, chlorides, and dilute acids .
- High Wear and Galling Resistance: The inclusion of Nickel (Ni) and Iron (Fe) refines the grain structure and enhances the alloy's hardness, making it highly resistant to wear, abrasion, and galling in high-stress friction environments.
- Thermal Stability: CA104 maintains excellent mechanical properties at elevated temperatures, resisting the softening and creep that plague many other copper-based alloys.
Hard Data: Chemical Composition and Mechanical Performance
The superior performance of CA104 is directly attributable to its precise alloying elements. It is a complex alloy, not just a simple mix of copper and aluminium.
Chemical Composition (Typical Weight %)
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Element
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Range (wt%)
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Function in Alloy
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Copper (Cu)
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Balance (approx. 79-80%)
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Base metal
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Aluminium (Al)
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8.5 – 11.0%
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Primary strengthening agent; forms protective oxide layer
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Nickel (Ni)
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4.0 – 5.5%
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Enhances corrosion resistance and mechanical strength
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Iron (Fe)
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4.0 – 5.5%
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Refines grain size, increases hardness and wear resistance
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Manganese (Mn)
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0.5% max
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Deoxidizer; secondary strengthening
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Mechanical Property Comparison
The following table and chart illustrate the significant mechanical advantage of CA104 over two other common bushing materials: Phosphor Bronze (PB102 / C51000) and Leaded Gunmetal (LG2 / C83600).
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Property
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CA104 (Al Bronze)
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PB102 (Phosphor Bronze)
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LG2 (Leaded Gunmetal)
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Tensile Strength (N/mm}^2)
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700 – 850
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350 – 450
|
250 – 300
|
|
Yield Strength (N/mm}^2)
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350 – 450
|
200 – 250
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120 – 150
|
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Hardness (HB)
|
170 – 220
|
90 – 120
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60 – 80
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Load Capacity
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Very High
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Medium
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Low-Medium
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Seawater Resistance
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Outstanding
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Good
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Moderate
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Engineering Note: Due to the high hardness of CA104, the mating shaft must be carefully selected. To prevent premature wear of the bushing, the shaft material should typically be a hardened steel with a surface hardness greater than that of the CA104 bushing.
Design Decisions: Lubrication Systems for CA104 Bushings
The performance of a CA104 bushing is heavily influenced by its lubrication design. Engineers typically choose between two primary configurations based on the application’s maintenance schedule and operating environment.
A. Spiral Groove Design (Traditional Lubrication)
This design involves machining internal grooves (spiral, figure-eight, or double-ring patterns) into the bore of the CA104 bushing.
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Feature
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Description
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Principle
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Relies on external, periodic injection of oil or grease. The grooves distribute the lubricant to form a hydrodynamic film between the shaft and the bushing.
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Best For
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High-speed rotation, applications where a fluid film is necessary, and environments where regular maintenance is feasible.
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Advantage
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Lower initial cost, excellent heat dissipation (as the lubricant carries heat away).
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B. Embedded Solid Lubricant (JDB / Graphite Plugged)
This is the modern, high-performance solution. Holes are drilled into the CA104 base metal, and solid lubricant plugs (typically graphite orMoS) are pressed into them, covering 25% to 30% of the bearing surface.
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Feature
|
Description
|
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Principle
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Self-lubricating. During operation, the solid lubricant transfers a thin, low-friction film onto the shaft surface. This provides lubrication even when no external oil is present.
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Best For
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High-load, low-speed oscillating motion, intermittent operation, high-temperature, submerged (underwater), or inaccessible locations where maintenance is impossible.
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Advantage
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Maintenance-free operation, extremely low friction coefficient, eliminates the risk of “seizing” (galling) due to lubricant starvation.
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Critical Applications: Where CA104 Reigns Supreme
CA104 is not a general-purpose alloy; it is a specialist material reserved for applications where failure is not an option and environmental conditions are severe.
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Application Sector
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Specific Component
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Recommended Bushing Type
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Rationale
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Marine & Naval
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Propeller Shaft Bushings, Rudder Bearings, Seawater Pump Components
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Plain or Grooved
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Unmatched resistance to saltwater corrosion, erosion, and cavitation .
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Oil & Gas
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Valve Stem Nuts, Subsea Actuator Joints, Downhole Tooling
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Solid Lubricant or Special Threaded
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Withstands corrosive media (e.g., sulfides) and high pressures where standard bronzes fail rapidly.
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Heavy Construction
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Excavator Bucket Pins, Crusher Eccentric Bushes, Crane Pivots
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Solid Lubricant (JDB)
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High impact resistance and tolerance for dusty environments. Solid lubricant prevents dust from mixing with grease to form an abrasive paste.
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Aerospace & Defence
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Landing Gear Components, High-Stress Fasteners
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Wrought Bar/Forgings
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High strength-to-weight ratio and stable performance across a wide temperature range.
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The Final Verdict: CA104 vs. The Competition
When making a procurement decision, understanding the limitations of alternative materials is as important as knowing the strengths of CA104.
CA104 vs. Phosphor Bronze (PB102)
- The Contrast: PB102 is a Tin Bronze, prized for its good wear characteristics and lower cost.
- The Logic: CA104 offers nearly double the tensile strength and significantly higher hardness.
- Conclusion: Choose PB102 for general-purpose, moderate-load applications with good lubrication. Choose CA104 for heavy-duty, high-impact, and corrosive environments.
CA104 vs. Leaded Gunmetal (LG2)
- The Contrast: LG2 contains lead, which provides excellent machinability and inherent lubricity, making it a “forgiving” material.
- The Logic: LG2 is suitable for low-to-medium loads (e.g., general pumps and motors). CA104 is designed for extreme loads and harsh conditions.
Conclusion: LG2 is easier to work with and cheaper. CA104 offers a dramatically longer service life and higher reliability in critical machinery.
Industrial Aluminium Bronze CA104 Bushings Manufacturer
The Aluminium Bronze CA104 bushing is far from an ordinary component. It represents a strategic investment in reliability, combining extreme strength, exceptional corrosion resistance, and superior wear properties.
- If your application involves seawater or corrosive fluids, CA104 is the definitive choice.
- If you face maintenance challenges or high-load, low-speed operation, the CA104 base metal with embedded solid lubricant is the ultimate solution.
- If you are designing heavy-duty equipment, upgrading from traditional Phosphor Bronze to CA104 is a necessity for long-term operational integrity.
