Bronze
The Classic Bearing Alloy
For over 5,000 years, bronze has been humanity's go-to material for bearings. Its unique combination of wear resistance, load capacity, and corrosion resistance remains unmatched for heavy-duty industrial applications.
What is Bronze?
Bronze is a copper-based alloy, traditionally defined as copper alloyed with tin (Sn). The addition of tin dramatically improves copper's hardness, wear resistance, and strength while maintaining excellent thermal conductivity and corrosion resistance.
In modern bearing terminology, "bronze" encompasses a broader family of copper alloys including tin bronze, phosphor bronze, lead bronze, aluminum bronze, and manganese bronze. Each variant offers specific properties suited to different bearing applications.
JBM manufactures bronze bearings across the full spectrum — from solid cast bronze bushings to thin-wall wrapped bearings to self-lubricating graphite-plugged bearings.
Why Bronze for Bearings?
Wear Resistance
Tin forms hard intermetallic compounds that resist abrasion
High Load Capacity
Supports static loads up to 100+ N/mm² without deformation
Heat Dissipation
Copper base conducts heat away from friction surfaces
Anti-Galling
Dissimilar to steel — won't cold-weld to shafts
Tin Bronze Properties (C93200)
| Composition | Cu 83%, Sn 7%, Pb 7%, Zn 3% |
| Density | 8.93 g/cm³ |
| Melting Point | 880-1000°C |
| Tensile Strength | 240 MPa |
| Yield Strength | 125 MPa |
| Hardness | HB 65-75 |
| Max Static Load | 55 N/mm² |
| Max Speed (Lubricated) | 8 m/s |
| Temperature Range | -40°C to +250°C |
Common Names
SAE 660 • Bearing Bronze • Leaded Tin Bronze • Gun Metal
Types of Bronze for Bearings
Different bronze alloys are optimized for specific bearing applications. Understanding each type helps you select the right material for your requirements.
Tin Bronze
Cu + 5-12% SnThe original bearing bronze. Tin creates hard δ-phase particles that resist wear. Excellent for moderate loads and speeds. Good corrosion resistance.
- General industrial bushings
- Pump & valve components
- Marine hardware
Leaded Tin Bronze
Cu + Sn + 5-25% PbLead additions dramatically improve machinability and create a built-in lubricant. Lead particles smear under load, protecting against seizure. The workhorse bearing alloy.
- Heavy machinery bushings
- Hydraulic equipment
- Construction equipment
Phosphor Bronze
Cu + 5-10% Sn + 0.2% PPhosphorus deoxidizes the melt, creating a denser, stronger alloy. Excellent fatigue resistance and spring properties. Ideal for wrapped and thin-wall bearings.
- Wrapped bronze bearings
- Electrical connectors
- Springs & clips
Aluminum Bronze
Cu + 9-14% Al + Ni/FeAluminum forms a protective oxide layer, providing exceptional corrosion resistance — especially in seawater. Very high strength and hardness. Non-sparking.
- Marine bearings
- Heavy-duty bushings
- Oil & gas equipment
Manganese Bronze
Cu + Zn + Al + Mn + FeActually a high-strength brass. Exceptional strength, impact resistance, and wear properties. Often used with graphite plugs for self-lubrication.
- Graphite-plugged bearings
- Heavy load, slow speed
- Mold & die industry
Silicon Bronze
Cu + 3-4% Si + MnHigh strength with excellent corrosion resistance and weldability. Good for corrosive environments where weld repair may be needed.
- Chemical equipment
- Pole line hardware
- Weldable components
Bronze Bearing Alloy Grades
Detailed comparison of common bronze bearing alloys with their specifications and typical applications.
| UNS / SAE | Type | Cu % | Sn % | Other | Hardness | Strength | Application |
|---|---|---|---|---|---|---|---|
| C93200 / SAE 660 | Leaded Tin | 83 | 7 | Pb 7%, Zn 3% | HB 65 | 240 MPa | General purpose bearings |
| C93700 / SAE 64 | High-Lead Tin | 80 | 10 | Pb 10% | HB 60 | 220 MPa | Medium speed, medium load |
| C90300 | Tin Bronze | 88 | 8 | Zn 4% | HB 70 | 310 MPa | Gears, wear plates |
| C52100 / CuSn8 | Phosphor Bronze | 92 | 8 | P 0.2% | HB 95 | 450 MPa | Wrapped bearings, springs |
| C95400 | Aluminum Bronze | 85 | - | Al 11%, Fe 4% | HB 170 | 585 MPa | Marine, heavy duty |
| C95500 | Ni-Al Bronze | 81 | - | Al 11%, Ni 4%, Fe 4% | HB 195 | 690 MPa | Highest corrosion resistance |
| C86300 | Manganese Bronze | 63 | - | Zn 25%, Al 6%, Mn 3% | HB 225 | 795 MPa | Graphite plugged, heavy load |
Bronze Bearing Manufacturing Methods
Bronze bearings are produced through different manufacturing processes, each offering unique advantages.
Cast Bronze
Centrifugal, Continuous, Sand Casting
Molten bronze is cast into bars or near-net shapes, then machined to final dimensions. Centrifugal casting produces the densest, highest-quality material. Best for large bearings and custom shapes.
- Highest load capacity
- Large sizes available
- Custom shapes possible
- Repairable/machinable
Wrapped Bronze
Cold-Rolled Strip Formation
Bronze strip (usually CuSn8 phosphor bronze) is roll-formed into cylindrical bushings with a longitudinal split seam. Creates thin-wall, high-strength bearings with excellent fatigue properties.
- Thin wall saves space
- High fatigue strength
- Consistent quality
- Cost-effective for volume
Sintered Bronze
Powder Metallurgy
Bronze powder is compacted and sintered, creating a porous structure that holds oil. Self-lubricating when vacuum-impregnated. Ideal for small, high-volume bearings.
- Self-lubricating
- Maintenance-free
- Quiet operation
- Low cost in volume
Bimetal Bronze
Steel-Backed Sintered Layer
Porous bronze layer sintered onto steel backing strip, then formed into bearings. Combines steel's strength with bronze's bearing properties. Standard for automotive bushings.
- High load capacity
- Steel housing fit
- Lead-free options
- Automotive approved
Bronze vs. Other Bearing Materials
| Property | Bronze | PTFE Composite | Cast Iron | Nylon |
|---|---|---|---|---|
| Load Capacity | Very High (100+ N/mm²) | High (250 N/mm²) | High | Low (40 N/mm²) |
| Speed Capability | Medium-High (8 m/s) | High (10+ m/s) | Low | Medium |
| Temperature Range | -40°C to +300°C | -200°C to +280°C | -40°C to +400°C | -40°C to +100°C |
| Self-Lubricating | With graphite plugs | Yes (inherent) | No | Limited |
| Impact Resistance | Excellent | Good | Good | Fair |
| Machinability | Excellent | Good | Good | Good |
| Corrosion Resistance | Good-Excellent | Excellent | Poor | Good |
| Cost | Medium-High | Medium | Low | Low |
| Best For | Heavy loads, impact, high temps | Maintenance-free, clean | Low speed, lubricated | Light duty, low cost |
Where Bronze Bearings Excel
Bronze remains the material of choice for the world's most demanding bearing applications — wherever high loads, shock, and reliability are critical.
Construction Equipment
- Excavator boom bushings
- Loader arm pivots
- Crane swing bearings
- Bulldozer track pins
- Backhoe linkages
Marine & Shipbuilding
- Rudder bearings
- Stern tube bushings
- Winch bearings
- Deck equipment
- Propeller shaft bushings
Steel & Rolling Mills
- Roll neck bushings
- Chock liners
- Coiler mandrels
- Furnace car bearings
- Caster guides
Hydraulic Equipment
- Cylinder rod bushings
- Piston wear rings
- Valve guides
- Pump bearings
- Actuator pivots
Mining Equipment
- Crusher bushings
- Conveyor bearings
- Dragline components
- Shovel pivots
- Screening equipment
Power Generation
- Turbine bearings
- Generator bushings
- Hydropower equipment
- Wind turbine yaw bearings
- Governor bushings
Choosing the Right Bronze Alloy
Best all-around choice. Good balance of load, speed, and cost. Excellent machinability with lead content.
Aluminum bronze provides superior seawater corrosion resistance. Ni-Al bronze (C95500) for most severe conditions.
High-strength brass base with embedded graphite plugs. Maintenance-free for hard-to-reach locations.
Phosphor bronze wrapped bearing. Excellent fatigue strength in compact form factor.
Manganese bronze offers highest strength and hardness. Ideal for shock loads and edge loading.
Nickel replaces lead for environmental compliance. Aluminum bronze is naturally lead-free.
Need help selecting the right bronze alloy? Our engineers can recommend the optimal material for your specific application.
Contact EngineeringNeed Bronze Bearings?
JBM manufactures bronze bearings in all major alloy grades — from SAE 660 leaded bronze to marine-grade aluminum bronze. Cast, wrapped, sintered, or bimetal — we have the right bronze solution for your application.
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