Aluminum Bronze for Bearings and Bushings
Manufacture and application of bronze rings, particularly in machinery and equipment.
Aluminum Bronze for Bearings and Bushings
Aluminum bronze is what you specify when a tin bronze lining is no longer enough: loads two to three times higher, temperatures that soften ordinary bronzes, impact and edge loading, and seawater. The aluminium content builds a hard, strong copper-aluminium matrix, and the nickel-bearing grades add heat-treatable strength. The price is a hard, galling-prone surface that needs the right shaft pairing and machining practice.
Grades in this family
| UNS | Cross-reference | Form | Defining trait |
|---|---|---|---|
| C95400 | CB333G (EN); CuAl10Fe5Ni5-C (near) | Cast bushings, wear plates, gears | The workhorse: highest general strength of the cast bronzes |
| C95500 | CuAl10Ni5Fe4 | Cast, heat-treatable | Ni-alloyed; heat treatment pushes strength further |
| C95800 | CuAl10Ni5Fe4 (NAB, marine) | Cast propellers, pump and valve parts | Nickel aluminium bronze with seawater corrosion resistance |
| C63000 | CuAl10Ni5Fe4 (wrought), CW307G | Wrought bar, plate | Wrought strength; machined from solid for high-duty bushings |
| C64200 | CuAlSi… aluminium-silicon bronze | Wrought bar | Free-machining alternative where Al-bronze strength is not needed |
Composition limits
| UNS | Cu | Al | Fe | Ni | Mn | Si |
|---|---|---|---|---|---|---|
| C95400 | ≥83.0 | 10.0–11.5 | 3.0–5.0 | ≤2.5 | ≤0.50 | — |
| C95500 | ≥78.0 | 10.0–11.5 | 3.0–5.0 | 3.0–5.5 | ≤3.5 | — |
| C95800 | ≥79.0 | 8.5–9.5 | 3.5–4.5* | 4.0–5.0* | 0.8–1.5* | ≤0.10 |
| C63000 | rem. | 9.0–11.0 | 2.0–4.0 | 4.0–5.5 | ≤1.5 | — |
| C64200 | ≥91.0 | ≤0.20 | ≤0.10 | ≤0.20 | — | 2.8–4.0 |
*C95800 limits shown per the typical marine NAB specification (ASTM B148); individual standards differ slightly in Fe/Ni/Mn ranges — always check the drawing’s named standard. Single values are maxima.
Mechanical properties and heat treatment
| Condition | Tensile, MPa | Yield (0.5% ext), MPa | Elongation, % | Brinell |
|---|---|---|---|---|
| As-cast | ~515 | ~205 | ~12 | ~170 |
| Quench and tempered (TQ50) | ~620 | ~310 | ~9 | ~195 |
C95500 and C63000 are heat-treatable nickel aluminium bronzes: solution treatment near 900 °C followed by controlled quench and temper rearranges the phases and raises yield strength substantially above the as-cast values. Three practical consequences:
- Higher allowable stress — heat-treated NAB supports bushing designs where as-cast C95400 would run over its load limit.
- Distortion control — heavy castings move during quench; leave machining allowance for final dimensioning after heat treatment.
- Weld repair policy — welded repairs to heat-treated parts require re-heat treatment or a documented alternative; decide this before, not after, the weld.
Seawater: why C95800 is the marine grade
C95800 (nickel aluminium bronze, NAB) is the cast copper alloy standard for propeller shafts, pump shafts and valve trim in seawater. The nickel-rich phase forms a tight, self-repairing oxide film that resists impingement attack, cavitation erosion and crevice corrosion far better than tin bronzes. For bearings, the practical points are:
- It runs acceptably against seawater-lubricated compatible shafts in stern tubes and rudder bearings when paired with the right surface and clearance.
- It is widely used as the bushing/housing material around NAB propeller shafts to avoid galvanic mismatch.
- Cavitation and silt erosion — not static corrosion — set the real life of marine sliding parts, so duty cycle matters more than nominal corrosion tables suggest.
Where marine and bearing requirements split
A part specified as NAB for corrosion (a pump casing) is not automatically the right lining for a heavily loaded bushing. For the bearing function itself, compare C95800 against heat-treated C95500 on PV and hardness, and against graphite-plugged bronze where lubrication at sea is unreliable.
The galling question: shaft pairing
Aluminium bronze is hard and, against a similar hard surface, prone to galling in boundary lubrication. Two mitigations are standard practice:
- Hard, smooth shafts. Pair with hardened steel (≈50 HRC or more), ground to a fine finish. The rougher the shaft, the faster an Al-bronze lining wears it.
- Never pair Al-bronze against itself without a validated anti-galling measure (coating, grease with EP additives, or an interposed lining).
- Embeddability is low. In dirty environments, Al-bronze needs clean lubrication or filtration; otherwise a leaded tin bronze or a graphite-plugged design survives better at lower loads.
Customization Bronze rings
The rings are manufactured to meet exact client specifications, with precise measurements and tailored designs.
Bronze rings Specific Uses
Advantages of Bronze Slip Rings
Precision Machining: Advanced machining techniques ensure tight tolerances and high accuracy, meeting the most demanding specifications.
Grades in this family
Selection guidance
| Situation | First choice | Reason |
|---|---|---|
| Heavy sleeve bearings, impact and edge loading | C95400 | Highest general strength of the cast bronzes, moderate cost |
| Load beyond as-cast C95400 limits, wear plates | C95500 (heat treated) | Heat-treatable Ni grade raises yield strength further |
| Seawater pumps, propeller-related bushings, valves | C95800 | Cavitation and seawater corrosion resistance |
| Machined-from-solid high-duty bushings, small lots | C63000 bar | Wrought soundness and strength, no casting lead time |
| Worm gear rim against hardened steel worm | CuSn12 | Conformability and scuffing resistance beat hardness here |
| Dirty or dry-running duty | Graphite-plugged bronze | Self-lubricating; hardness alone does not survive contamination |
Manufacturing Capabilities
Customization and Support
Manufacturers often provide bespoke solutions, working closely with clients to design and produce slip rings that meet specific operational needs. Technical teams can advise on material selection, design optimization, and performance enhancements.
By advanced CNC machining and high-quality bronze alloys, manufacturers can produce slip rings that deliver superior performance, reliability, and longevity in even the most challenging conditions.
