Bronze is a versatile and popular bearing material to work with for various applications. Its wide selection of alloys and compositions provides a host of properties. Bronze Bearings demonstrate strength, durability and corrosion resistance.
Both bronze and brass are copper-based alloys containing various other elements. They belong to materials referred to as “red metals” because of their reddish color. Bronze Bushings (Copper - Tin ) are harder and stronger compared with Brass Bushings (Copper-Zinc), which are softer and thus more likely to deform or break.
Range of Properties
Bronze Bearings offer exceptional mechanical properties in various demanding operating and environmental conditions:
Strength
Low friction
Shock and impact resistance
High load capacity
Wide temperature range
Cost-effective solution
And since bronze is recyclable, it is considered as a sustainable material.
Bronze Bearing Applications
Bronze Bushings and Bearings are commonly used in high-load, low-speed and heavy-duty applications and equipment and can be found in a wide range of industries:
Aerospace (flight control system, landing gear assemblies, aircraft components)
Automotive (sway bars, control arms, vehicle suspension components)
Energy (gearbox assemblies and yaw mechanisms in wind turbines, turbine shafts in hydroelectric power plants)
Food processing
Industrial (pivot points, rotating shafts)
Bronze Bearing Types
Bronze Bushings can be produced in many shapes and dimensions:
Cylindrical Bearings (also called Sleeve Bearings): used to reduce friction and vibration under heavy loads and high temperatures
Flanged Bearings (and Double Flanged Bearings): typically used for light duty
Thrust Bearings (also called Thrust Washers): offering easy assembly, a high load capacity and resistance to harsh environments
Bearing Plates: Where low coefficient of sliding friction is desired
Pintle Bearings
Bronze Bearing Materials
Bronze Bushings are available in different alloys and compositions.
They are listed in five alloy families according to their compositions and properties:
Tin Bronze alloys for strength property
Leaded Tin Bronze for antifriction and machinability properties
High Leaded Tin Bronze alloys for lubrication and machinability properties
Aluminum Bronze alloys for strength and corrosion resistance properties
Manganese Bronze alloys for strength and corrosion resistance properties.
Oil Impregnated Sintered Bronze Bearings
Bronze Bearings can be made from sintered bronze or cast bronze.
Cast bronze is a very strong alloy thanks to its chemical composition. Cast bronze bearings are more resistant to corrosion and so ideal for wet environments.
Sintered bronze bushings are ideal for applications under high and low speeds conditions and a wide range of temperatures.
Do Bronze Bearings Need Oil or Grease?
Bronze bearings require an external lubricant, oil or more often grease.
The lubricant improves the sliding properties, reduces wear, prevents corrosion and extends service life.
Grease grooves are typically wider and deeper than oil grooves. This is to hold a supply of grease and to provide for the thick grease to be forced in. Oil grooves typically vary in width but are shallower than grease grooves. Most oil grooves are operating in a constant loss or closed oiling system that continually feeds the less viscous oil to the grooves. Double loop groove & double figure eight groove recommended for grease only.
Maintenance-Free bronze bearings with graphite filled grooves and graphite plugs are available. The graphite acts as a dry lubricant and provides maintenance-free continuous lubrication. The ID groove patterns can be filled with a special hardenable graphite paste. Graphite Plugs can be press fit through the wall of the bearing with a special epoxy resin binder. Typical plug diameter is 7mm with a 25% surface coverage. The graphite plugs can be placed around special features of your parts. Graphite bronze parts should be run dry with no oil or grease. Our graphite plug bearings typically have a coefficient of friction between 0.10 and 0.15, depending on a variety of factors affecting performance.
Installation and Maintenance of Bronze Bearings
Assembly and maintenance of Bronze Bushes are critical to performance and durability.
The selection of the appropriate lubricant is crucial and depends on the operating conditions (load, speed and temperature).
A typical running clearance for a bronze bearing is around 0.001 inches per inch of shaft diameter; meaning, for a 1-inch shaft, you would aim for a clearance of approximately 0.001 inches between the shaft and the bearing bore, with variations depending on the specific application, load, speed, and type of bronze alloy used.
For example is the normal bearing clearance is .001” per inch of shaft diameter +.001”, i.e. 5” shaft = .006” (5.006”). Alternately, the clearance should be .00125”/inch of shaft diameter.
Shaft size: Larger shafts generally require slightly larger clearances.
Operating conditions: High-speed or high-load applications might need slightly smaller clearances for better stability.
Lubrication: Adequate lubrication allows for slightly larger clearances.
Type of bronze used: Different bronze compositions may have different wear characteristics, impacting clearance requirements.
Bearing Clearance Tolerance Chart:
For Shaft Dia. | Including OD | Clearance inches min | Clearance inches max |
1.500" | 1.750" | 0.0010 | 0.0012 |
1.750" | 2.250" | 0.0012 | 0.0015 |
2.250" | 2.750" | 0.0015 | 0.0020 |
2.750" | 3.500" | 0.0016 | 0.0025 |
3.500" | 4.250" | 0.0020 | 0.0028 |
4.250" | 5" | 0.0025 | 0.0035 |
5" | 5.500" | 0.0030 | 0.0040 |
5.500" | 6.500" | 0.0030 | 0.0045 |
6.500" | 7.250" | 0.0035 | 0.0050 |
7.250" | 8" | 0.0040 | 0.0055 |
8" | 9" | 0.0045 | 0.0060 |
9" | 10.500" | 0.0045 | 0.0065 |
10.500" | 11" | 0.0050 | 0.0075 |
11" | 12.500" | 0.0060 | 0.0085 |
12.500" | 14" | 0.0065 | 0.0090 |
Consult manufacturer guidelines:
Always refer to the specific recommendations from the bronze bearing manufacturer for the most accurate clearance values based on your application.
Bearing wear:
Over time, bronze bearings will wear, leading to increased clearance, so it's important to factor in potential wear when selecting initial clearance.
Proper installation:
Ensure the bearing is properly installed to avoid excessive clearance or interference with the shaft.
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