Understanding Bronze Bushings: A Comprehensive Guide

Choosing the right bronze bushing is simple and straightforward with the right information.
Whether you want to learn about the materials, manufacturing processes, types, advantages, and disadvantages of bronze bushings, this guide provides everything you need to know.
Therefore, if you want to learn more about bronze bushings, please read this guide.

bronze bushing Comprehensive Guide

What Is a Bronze Bushing?

A bronze bushing is a type of sliding bearing made from bronze, designed to support rotating or sliding parts within machinery. This component is crucial for various devices, offering durability and wear resistance. Its long lifespan and low maintenance requirements make it a staple in many mechanical systems.

What Is the History of bronze bushing?

The use of bronze dates back to around 4500 BC, initially for crafting weapons, decorations, and tools. A significant advancement in bronze bushings was the development of Oilite bearings in the 1920s. These bearings, made from a mixture of copper, tin, and graphite powders, are renowned for their strength and porosity which allows them to be oil-impregnated. This self-lubricating property means that Oilite bearings generally do not require additional lubrication once installed. As industry progressed, the corrosion resistance, durability, and heavy-load bearing capacity of bronze made it increasingly suitable for various industrial applications.

What Is the Other Term for bronze bushing?

Bronze bushings are also referred to as “Bronze Bearings” or “Bronze Sleeve Bushings.” These terms highlight their function as bronze-made sliding bearings that reduce friction and support mechanical components.

What Sizes Do Bronze Bushings Come In?

bronze bushing size

Standard Sizes

  • Metric dimensions are available in a broad range, with some types of inner diameters ranging from 8 millimeters to 50 millimeters.
  • Imperial dimensions also vary, with inner diameters from 5/16 inch to 2 1/2 inches.

Flanged Bronze Bushing Sizes

  • Inner Diameter (ID) and Flange Diameter (FD): Sizes can include 1/2″ ID x 3/4″ OD, 5/8″ ID x 7/8″ OD, 3/4″ ID x 1″ OD, up to 2″ ID x 2-1/4″ OD.

Custom Sizes

What Is the Tolerance of Bronze Bushings?

Tolerance Range

The tolerance of bronze bushings refers to the allowable deviation between the bushing and its specified dimensions to ensure proper fit and function. This range varies depending on the type and size of the bushing and is typically established by the manufacturer or according to international standards like ISO, DIN, or ANSI. Common tolerances for sliding bearings are often indicated as “g6” or “h9” for shaft fittings and “H7” for bearing housings.

General Rules of Thumb

  • A general rule of thumb for bronze bushing shafts is a clearance of 0.001 inches per inch of shaft diameter, with a maximum clearance around 5 inches.

Press Fit Tolerances

  • For press-fit bronze bushings, a good fit is generally around 0.0005-0.001 inches per inch of diameter. For instance, a 3-inch bushing might have approximately 0.002 inches of press fit, and a 5-inch bushing might have about 0.003 inches.

Manufacturing Tolerances

  • The design and manufacturing of bushings typically exceed the nominal outer diameter by 0.002 to 0.003 inches for standard sizes up to 3 inches in diameter. For diameters larger than 3 inches, the outer diameter is designed to be about 0.003 to 0.005 inches above the nominal size.

How Is a Bronze Bushing Made?

Cast Bronze Bushings

Cast bronze bushings are created through a casting process. This involves melting a bronze alloy, typically consisting of copper, tin, and elements like zinc or lead. The molten alloy is then poured into molds to form the bushings. After casting, the bushings are machined to the required dimensions and tolerances using CNC lathes.

Sintered Bronze Bushings

Sintered bronze bushings are manufactured using powder metallurgy techniques. This process begins by pressing bronze powder into molds sized for the bushings. The powder is compacted tightly, and the bonded powder particles are sintered in a furnace. Sintering involves heating the particles to a temperature high enough to bond them without melting. This process reduces the material’s porosity but retains about 25% porosity for oil-impregnated bushings. After sintering, the bushings are pressed to achieve the desired tolerances and then vacuum impregnated with oil to enhance their self-lubricating properties, reducing the need for additional lubrication.

What Materials Are Used in Bronze Bushings?

Bronze bushings are made from various bronze alloys, each tailored for specific applications with unique properties. Some notable materials include:

  1. SAE 660 (C93200)Bearing Bronze: Known for its machinability and wear resistance, this tin bronze alloy is commonly used across many industries for bearings and bushings.
  2. SAE 841 Sintered Bronze: This oil-impregnated bronze sleeve bearing offers greater load-bearing capacity and corrosion resistance compared to stamped steel bearings, suitable for high-temperature applications.
  3. SAE 863 Bronze: Known for its strength, this oil-impregnated bearing is used for higher strength self-lubricating metal powder bearings.
  4. SAE 954 Aluminum Bronze: Also known as manganese bronze, this alloy offers excellent strength and corrosion resistance, ideal for grooved bushings.
  5. Silicon Bronze: Made from copper and silicon, this alloy has a very low friction coefficient and is durable, making it suitable for bearings.
  6. Phosphor Bronze: Mainly composed of copper, this material is favored for its fine grain, low friction coefficient, and fatigue resistance. A protective layer formed by the reaction of copper with phosphorus enhances its lifespan.
  7. CuSn7Zn4Pb7-Bronze (CC493K): A cost-effective red bronze alloy, it performs well under moderate loads with good emergency running properties and wear resistance.
  8. Copper Tin 12-C: A tough bearing material with good sliding properties and wear resistance, especially suitable for high surface pressure and impact conditions.
  9. Copper Tin 8: Known for its excellent sliding performance, high wear resistance, and heat resistance, it is suitable for high-speed and high-load applications under adequate lubrication.

What Are the Different Forms of Bronze Bushings?

Different Forms of Bronze Bushings

Bronze bushings come in various forms to accommodate different mechanical and structural needs

  1. Plates, Washers, and Sleeves
    • Plates: Created by pressing metal to form a flat surface with a central hole.
    • Washers: Used to distribute the load of a threaded fastener like a screw or nut.
    • Sleeves (Brass Sleeve Bushing): Cylindrical components that reduce friction between moving parts.
  2. Plain Sleeve Bushings
    • These are the simplest and most common type of bronze bushings, offering an effective solution for reducing friction between moving parts.
  3. Flanged Sleeve Bushings
    • These bushings have a flange at one end, acting as a thrust bearing to prevent axial movement and ensure stability.
  4. Thrust Washers
    • Designed to support axial loads, these flat bearings prevent movement along a shaft’s axis.
  5. Wear Plates
    • Used in areas of machines where sliding motion occurs, protecting surfaces from wear.
  6. Cylindrical Bearings (Sleeve Bearings)
    • These bearings reduce friction between rotating shafts and stationary support members and are among the most common types of bronze bushings.
  7. Split Bronze Bearings
    • These bearings are designed for easy installation and maintenance and come in three types:
      • Perfect Halved Bushings: Yield two halves of the exact same size, interchangeable with any other halves manufactured to the same specification.
      • Matched Halved Bushings: Match only with the corresponding opposite half they were manufactured with.
      • Bushings Split After Machining: Do not complete a full circle due to material loss during splitting, making them the most economical option.

What Are the Advantages of Bronze Bushings?

Bronze bushings offer a range of benefits suitable for various industrial applications:

  1. Corrosion Resistance: Excellent resistance to corrosive elements and environments makes bronze bushings ideal for applications exposed to moisture, chemicals, and other corrosive substances.
  2. High-Temperature Operation: Capable of functioning effectively at high temperatures, offering better thermal conductivity than most steels, which is beneficial in many industries, particularly in critical working parts.
  3. Wear Resistance: Bronze bushings are resistant to wear even under continuous use, able to withstand friction that often causes issues, ensuring longevity and reliability.
  4. Machinability: Easy to machine, with high dimensional accuracy and surface finish quality, allowing them to adapt to various complex shapes and sizes.
  5. Strength and Durability: Bronze bearings are hard and sturdy, while brass bearings are softer and more prone to deformation. This strength and durability make them suitable for high-load, low-speed, and heavy-load applications.
  6. Self-Lubricating: For example, sintered bronze bushings feature self-lubricating properties, almost eliminating the need for maintenance and offering cost-efficiency. This reduces the need for regular lubrication maintenance.
  7. Versatility: Bronze is a versatile material with a variety of alloys and compositions that can provide multiple characteristics for specific applications.
  8. Sustainability: Bronze is considered a sustainable material since it is recyclable, contributing to environmental conservation efforts.
  9. Cost-Effectiveness: Despite their high performanceand durability, bronze bushings are cost-effective, balancing quality with economy.
  10. Reduced Maintenance Costs: For instance, bronze bushings with graphite plugs can reduce the need for regular maintenance and lubrication, saving on labor, downtime, and lubrication costs.

What Are the Disadvantages of Bronze Bushings?

Advantages of Bronze Bushings

While bronze bushings offer many advantages, they also have some drawbacks:

  1. Cost: Due to the cost of bronze materials and related manufacturing processes, bronze bushings may be more expensive than other types of bushings.
  2. Complex Manufacturing Process: Particularly for cast bronze bushings, the manufacturing process is complex and time-consuming, thus more costly. This process includes casting the bronze alloy, machining it on CNC lathes, and possibly adding lubrication grooves or holes.
  3. Increased Weight: Bronze bushings are heavier than some alternatives like plastic bushings. In applications where weight reduction is a priority, the increased weight may be a disadvantage.
  4. Corrosion Potential: Although bronze bushings have good corrosion resistance, they can still corrode under certain environmental conditions depending on the alloy used. This can affect their durability and lifespan.
  5. Mechanical Strength Limitations: Oil-impregnated bronze bushings made through powder metallurgy (P/M) processes have certain limitations in mechanical strength, making them less suitable for high-load applications.
  6. Contamination Risk from Oil: Oil-impregnated bronze bushings contain oil, which can potentially contaminate other parts or substances they come into contact with. Therefore, they are not suitable for applications where contamination could be an issue.

What Are the Applications of Bronze Bushings?

application of Bronze Bushings

Due to their wear resistance, corrosion resistance, and high-load capacity, bronze bushings are widely used in various industries:

Industrial Machinery

  • Pivots and rotating shafts: Used in manufacturing machinery such as presses, milling machines, and lathes, providing low friction and reliable motion under heavy loads.
  • Heavy equipment and motors: Due to their durability and wear resistance, bronze bushings are extensively used in heavy equipment and motors, helping to save costs and reduce maintenance.

Automotive Industry

  • Suspension components: Bronze bushings are used in anti-roll bars, control arms, and automobile suspension systems, providing elasticity and damping vibrations under heavy loads, improving handling, and ensuring a smooth driving experience.

Aerospace Industry

  • Flight control systems and landing gear: Bronze bushings are employed in flight control systems, control surfaces, landing gear components, and other aircraft parts, providing reliability even under large temperature fluctuations and high speeds.

Marine Industry

  • Deck equipment, steering mechanisms, and propulsion systems: Ideal for marine applications due to their ability to withstand heavy loads and corrosion, particularly in seawater environments.

Energy and Power Generation

  • Wind turbines and hydroelectric power stations: In wind turbines, bronze bushings are used in gearbox components, yaw mechanisms, and blade pitch systems. Hydroelectric power stations rely on bronze bushings to support turbine shafts for power generation.

Food Processing

  • Machinery and equipment: Sintered bronze bushings are used in the food processing industry due to their high-temperature resistance, corrosion resistance, and self-lubricating structure.

Steel Manufacturing

  • Equipment and machinery: Bronze bushings are used in the steel manufacturing industry, where their properties help reduce mechanical friction and wear.

Do Bronze Bushings Need to Be Greased?

Yes, bronze bushings generally require lubrication to function effectively. Grease is the most common lubricant for solid bronze bushings because it is thicker and less likely to be squeezed out under load conditions. However, the exact amount of grease needed varies based on factors such as the load, speed, and environmental conditions of the application. Over-lubrication can lead to issues like seizure and increased maintenance due to the attraction of contaminants. Regular, significant use of lubricating oil is necessary to ensure the longevity and optimal performance of the bushings, but over-lubrication should also be avoided.

In contrast, oil-impregnated bronze bushings and self-lubricating bronze bushings reduce or eliminate the need for manual lubrication. The manufacturing process for oil-impregnated bronze bushings creates a porous structure that achieves self-lubrication during operation. Similarly, self-lubricating bronze bushings incorporate materials like graphite in their structure, providing continuous lubrication without the need for external grease or oil. These self-lubricating options offer a low-maintenance cost solution, especially suitable for applications where regular lubrication is difficult or impractical.

What Is the Difference Between Brass and Bronze Bushings?

Brass Bushing VS Bronze Bushing

The distinction between brass and bronze bushings lies in their composition, properties, and applications:

Composition

  • Brass Bushings: Brass is an alloy primarily composed of copper and zinc, which may also contain small amounts of tin and other metals. The proportion of copper to zinc varies, affecting the colorand properties of the brass.
  • Bronze Bushings: Bronze is an alloy mainly made from copper and tin but may also contain elements like zinc, arsenic, aluminum, silicon, phosphorus, and manganese. The specific elements added to copper affect the properties of the bronze alloy.

Properties

  • Hardness and Strength: Bronze bushings are generally harder and stronger than brass bushings, making bronze more suitable for high-load and high-impact applications. Brass bushings are softer and more malleable, which can be advantageous in some applications but may also lead to deformation under stress.
  • Corrosion Resistance: Compared to brass bushings, bronze bushings generally have better corrosion resistance, especially in marine environments, due to the presence of tin in bronze, which enhances its corrosion resistance.
  • Wear Resistance: Bronze bushings have a higher usage coefficient and are more wear-resistant than brass bushings, making them more durable and suitable for applications involving friction and wear.
  • Lubrication: Bronze bushings typically require lubrication to function effectively, such as lubricating oil or grease, which must be used during installation and throughout operation. Brass bushings can also be self-lubricating, which may not bond with steel, a beneficial property in some applications.
  • Color: Brass has a pale yellow color, while bronze has a warm reddish color. This could be considered for aesthetic or material identification purposes.

Applications

  • Bronze Bushings: Due to their strength and wear resistance, bronze bushings are commonly used in heavy-duty applications such as steel manufacturing, food processing, valves, and automotive. Bronze bushings are preferred for applications requiring high impact resistance and durability.
  • Brass Bushings: Brass bushings are used in applications where flexibility and formability are more critical. With their rust prevention and anti-friction properties, they are also used in water pump bushings, motors, and sliding bearings.

Conclusion

As you can see, bronze bushings are used across various industries and are available in many types. If you need more information about bronze bushings or are interested in obtaining a quote, please contact us.
We offer a wide range of bronze bushing types and are ready to provide you with a free quote upon request. Whether you are looking for standard sizes, custom specifications, or specific material properties, we are here to assist with all your bronze bushing needs.

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