When selecting self-lubricating bearings, how do we evaluate and choose matrix materials?

In mechanical transmission systems, self-lubricating bearings serve as "silent guardians," enduring dynamic loads while maintaining low friction and wear resistance over the long term without external lubrication. However, engineers often face a dilemma when balancing "performance, cost, and application suitability" among the three mainstream matrix materials: high-strength brass, tin bronze, and aluminum bronze. For example, high-strength brass (such as ZCuZn25Al6Fe3Mn3) is known for its high strength, tin bronze (such as ZCuSn10P1) is low in cost, and aluminum bronze (such as ZCuAl10Fe3) excels in high-temperature resistance. However, improper selection can lead to premature bearing failure or resource wastage.

1. Core Performance Comparison and Selection Logic

Mechanical Properties: Strength, Hardness, and Load-bearing Capacity

Selection Suggestions:

• Heavy/shock loads (such as mining machinery, shield machines): Prefer high-strength brass, which has a tensile strength three times that of tin bronze and an ultimate pressure 43% higher than aluminum bronze.

• Low-to-medium speed and light loads (such as textile machinery, conveyor belts): Tin bronze is lower in cost (about 30% less) but requires regular maintenance.

• High-temperature and medium loads (≤400℃): Aluminum bronze, due to its aluminum content, retains 80% of its strength at high temperatures (compared to 65% for high-strength brass).

Tribological Properties: Wear Rate and Lubrication Efficiency

Selection Suggestions:
• Long-term maintenance-free requirements: High-strength brass has the lowest wear rate (only 28% of tin bronze) and high lubricant embedding capacity, making it suitable for unmanned scenarios like wind turbine pitch bearings.
• Short-term low-cost solutions: Tin bronze has lower initial investment but a higher wear rate, requiring inspection of lubricant release status every 500 hours.
• High-temperature lubrication stability: Aluminum bronze forms a lubrication film 20% faster than high-strength brass at temperatures above 200℃, making it suitable for steel mill roller bearings.

Environmental Adaptability: Temperature and Corrosion Resistance

*Note: Salt spray test standard ASTM B117, 5% NaCl solution.

Selection Suggestions:

• Marine/chemical environments: Aluminum bronze has the best salt spray resistance (no pitting after 1000 hours), followed by high-strength brass; tin bronze is prone to dezincification corrosion and requires surface coating.

• Wide temperature fluctuations: Aluminum bronze maintains the best strength stability within the range of -50~400℃, followed by high-strength brass (hardness decreases by 15% after 300℃).

2. Economic Analysis and Life Cycle Cost

Initial Cost and Maintenance Expenses

• Material price per ton (2023 average): Tin bronze (68,000 yuan) < High-strength brass (72,000 yuan) < Aluminum bronze (85,000 yuan).

• Maintenance interval: High-strength brass (1200 hours) > Aluminum bronze (800 hours) > Tin bronze (500 hours).

• Comprehensive cost case: A cement plant switched to high-strength brass for its vertical mill bearings, reducing total costs (including replacements and downtime losses) by 41% over three years, while the aluminum bronze option reduced costs by 28%.

Failure Risk and Hidden Costs

• Tin bronze: Cost-effective under light loads, but wear rate increases dramatically under heavy loads, with a sudden failure risk three times higher than that of high-strength brass (source: "Heavy Machinery," 2023, Issue 4).

• Aluminum bronze: Excellent high-temperature performance but difficult to cold work, with processing costs 25% higher than those of high-strength brass.

3. Decision-Making Flowchart and Quick Selection Guide

Determine Application Priority:

Heavy/shock loads? → High-strength brass

High temperatures (>300℃)? → Aluminum bronze

Severe corrosion environment? → Aluminum bronze or high-strength brass

Low cost/light loads? → Tin bronze

Verify Lubrication Requirements:

High maintenance-free requirements? → High-strength brass (high lubricant embedding capacity)

Regular maintenance possible? → Tin bronze or aluminum bronze

Life Cycle Cost Calculation:

Considering equipment downtime losses and replacement frequency, select the option with the lowest overall cost.

The essence of selection is a "trade-off between performance requirements and economics":

• High-strength brass is a "versatile player" for heavy loads, corrosion resistance, and maintenance-free scenarios, suitable for high-end equipment pursuing long-term reliability.

• Tin bronze, with its low cost, remains competitive in light-load, low-speed, and short-term projects.

• Aluminum bronze locks in special application demands with its "single advantages" in high-temperature resistance and corrosion resistance.

In future trends, high-strength brass, further enhanced through nanomodification (such as adding silicon carbide particles), may become a more universally applicable solution.

Please feel free to contact Zhejiang Mingxu Machinery Manufacturing Co., Ltd.: [email protected] for more advice on material selection for self-lubricating bearings.