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Sliding Bearing Material Selection Strategies: Performance Comparison and Application Analysis

In the design and selection of sliding bearings, material properties directly determine their load capacity, service life, and operational stability. Different metal matrices exhibit significant variations in hardness, temperature resistance, friction compatibility, and limiting PV (pressure x velocity) values, requiring precise matching based on operating conditions.

 

Tin-based babbitt alloys (such as B83/B88)

 

Known for their excellent embeddability and conformability, they effectively absorb impurities and accommodate minor shaft deformations. They also possess excellent corrosion resistance and are suitable for medium- and low-speed, heavy-load, and frequently impacted applications. However, their relatively low matrix strength and tendency to soften at elevated temperatures limit their application in high-speed or high-temperature environments.

 

Tin bronze (typical grade: ZCuSn10P1)

 

 

Offering high mechanical strength and wear resistance, it is suitable for high-load, continuous-duty applications. However, its hard surface leads to poor running-in performance, requiring high journal precision, and prone to localized hot spots during initial operation, requiring meticulous assembly.

 

Aluminum-based composite alloys (such as AlSn20Cu)

 

Low density enables lightweight design, while also offering excellent thermal conductivity and high-temperature stability, making them particularly suitable for high-speed, high-temperature, and variable operating conditions. Their self-lubricating properties excel in automotive engine main bearings, making them a key material choice for modern internal combustion engines.

 

Performance Comparison:

 

Through hardness testing, thermal stability analysis, and PV limit value assessment, it can be seen that while babbitt alloy is soft, it offers strong compatibility; bronze offers excellent load-bearing properties but requires precise fit; and aluminum-tin alloys offer advantages in speed and temperature tolerance, making their overall performance more suitable for dynamic and complex operating conditions.

 

Application Case Analysis:

Why are aluminum-tin alloy bearings commonly used in mainstream automotive engines?

The answer lies in their excellent fatigue strength and heat dissipation capabilities. Frequent engine starts and stops, coupled with high-speed operation, result in drastic thermal load fluctuations. Aluminum-based materials not only quickly dissipate frictional heat but also maintain lubrication through their soft phase during temporary oil film breaks, preventing seizure and significantly improving reliability.

 

The selection of bearing materials requires a balance between four key factors: load-bearing capacity, running-in, temperature resistance, and lifespan. There is no "universal material". Only by conducting a systematic evaluation based on actual working conditions can the optimal balance between performance and cost be achieved.