Understanding Plain Cast Bronze Sleeve Bearings: An Essential Guide

Plain cast bronze sleeve bearings, also known as bushings, are a versatile and widely used component in various industrial applications. They combine durability, load-carrying capacity, and anti-friction properties to deliver optimal performance. This article aims to provide a comprehensive overview of plain cast bronze sleeve bearings, including their composition, properties, applications, standards, and installation considerations.

What Are Plain Cast Bronze Sleeve Bearings?

A plain cast bronze sleeve bearing is a cylindrical component made from high-quality bearing bronze, typically C93200 alloy, that serves as a bearing surface between moving parts. These bearings help reduce friction between rotating shafts and stationary housings, enabling smooth motion and protecting the assembly from wear and tear.

Composition and Properties

Plain cast bronze bearings are often made from a specialized bronze alloy known as C93200, containing:

• Copper (83%): Provides base material strength and wear resistance.
• Tin (7%): Improves corrosion resistance and enhances the overall strength.
• Lead (7%): Adds to the alloy’s anti-friction properties.
• Zinc (3%): Improves the bearing’s castability and machinability.

Physical Properties:

• Tensile Strength: 44,000 PSI
• Yield Strength: 27,000 PSI
• Elongation: 16% (in 2 inches)
• Brinell Hardness: 72

These properties ensure that plain cast bronze bearings can withstand substantial loads while maintaining low friction and high durability.

Standard Specifications and Tolerances

Plain cast bronze bearings typically adhere to the following standards:

• SAE 660: A widely recognized specification for bearing materials.
• ASTM B144-52
• Mil-B-16261(2), Grade VI
• Fed: QQ-L-225, Comp. 12
• QQ-B-691b(1), Comp. 12

Tolerances:

• Inner Diameter:

  • Up to 3 inches: ±.0010″
  • Over 3 inches: ±.0015″

• Outer Diameter:

  • Up to 3 inches: +.002″ to .003″
  • Over 3 inches: +.003″ to .005″

• Length: ±.005″

• Concentricity: .003″ T.I.R. (Total Indicator Reading)

Applications

Plain cast bronze bearings are valued for their high load-carrying capacity and excellent anti-friction properties, making them suitable for various industries:

• Automotive: Engine components, suspension systems, and transmissions.
• Manufacturing: Conveyors, pumps, and heavy machinery.
• Aerospace: Aircraft control systems and landing gear.
• Marine: Propulsion systems and rudder assemblies.
• Agriculture: Equipment like tractors and harvesters.

Installation Considerations

When installing plain cast bronze bearings, the following factors should be considered to ensure optimal performance:

1. Press Fit: Bearings with relatively thick walls and carrying moderate loads in one direction can tolerate a looser press fit than usual.

2. Clearance: For applications with exceptionally high speeds or heavy loads, greater clearance than normal should be allowed to prevent overheating and premature wear.

Conclusion

Plain cast bronze sleeve bearings are indispensable for a wide range of mechanical systems due to their versatility, durability, and reliable performance. Understanding their composition, applications, and proper installation practices will help engineers and procurement personnel make informed decisions to ensure the longevity and efficiency of these critical components. For further information or specific technical support, reach out to your trusted supplier or technical expert.