How to Judge Whether a Bearing Can Be Reused
During regular equipment maintenance, operational inspection and replacement of peripheral components, when assessing whether disassembled bearings can be reused, the external condition of bearings must be carefully inspected and recorded. After sampling lubricant to check its residual volume, thoroughly clean the bearings.
Inspect the conditions of raceway surfaces, rolling surfaces, fitting surfaces, as well as the wear state of the cage to identify any damage or abnormalities.
Furthermore, determine whether the bearing can be reused or replaced after evaluating the degree of bearing damage, machine performance, equipment importance, operating conditions, inspection cycles and other factors. If damage or abnormalities are found on the bearing, identify the root cause and formulate corrective measures.
Bearings with any of the following defects shall not be reused and must be replaced with new ones:
Cracks or fragments exist on any of the inner ring, outer ring, rolling element and cage;
Spalling occurs on any of the inner ring, outer ring and rolling element;
Severe scoring on raceway surfaces, ribs and rolling elements;
Severe wear of the cage or significant loosening of rivets;
Rust and scars on raceway surfaces and rolling elements;
Obvious brinelling and indentations on rolling surfaces and rolling elements;
Creep occurs on the inner diameter surface of the inner ring or the outer diameter surface of the outer ring;
Severe discoloration caused by overheating;
Severe damage to the sealing ring and dust cover of grease-sealed bearings.
Items to be inspected during operation include bearing rolling noise, vibration, temperature and lubrication status, as detailed below:
1. Bearing Rolling Noise
A sound meter is used to inspect the volume and sound quality of rolling noise generated by operating bearings. Even minor damage such as spalling on bearings will produce abnormal and irregular sounds, which can be distinguished with a sound meter.
2. Bearing Vibration
Bearings are highly sensitive to vibration-related damage. Defects including spalling, brinelling, corrosion, cracks and wear can all be reflected in bearing vibration measurements. Special bearing vibration measuring instruments (such as frequency analyzers) can measure vibration magnitude, and abnormalities can be deduced via frequency analysis.
Measured values vary depending on bearing operating conditions and sensor mounting positions. Therefore, judgment criteria shall be established after analyzing and comparing measured data of each machine in advance.
3. Bearing Temperature
Normally, the bearing temperature rises gradually after startup and reaches a stable state within 1 to 2 hours. The normal operating temperature of bearings varies with machine heat capacity, heat dissipation capacity, rotating speed and load.
Improper lubrication or incorrect installation will lead to sharp temperature rise and abnormal overheating. In such cases, operation must be stopped and necessary protective measures taken.
Thermal sensors can continuously monitor bearing operating temperature and trigger automatic alarms or shutdown when the temperature exceeds the specified limit, so as to prevent bearing burn-out accidents.
Inspect the conditions of raceway surfaces, rolling surfaces, fitting surfaces, as well as the wear state of the cage to identify any damage or abnormalities.
Furthermore, determine whether the bearing can be reused or replaced after evaluating the degree of bearing damage, machine performance, equipment importance, operating conditions, inspection cycles and other factors. If damage or abnormalities are found on the bearing, identify the root cause and formulate corrective measures.
Bearings with any of the following defects shall not be reused and must be replaced with new ones:
Cracks or fragments exist on any of the inner ring, outer ring, rolling element and cage;
Spalling occurs on any of the inner ring, outer ring and rolling element;
Severe scoring on raceway surfaces, ribs and rolling elements;
Severe wear of the cage or significant loosening of rivets;
Rust and scars on raceway surfaces and rolling elements;
Obvious brinelling and indentations on rolling surfaces and rolling elements;
Creep occurs on the inner diameter surface of the inner ring or the outer diameter surface of the outer ring;
Severe discoloration caused by overheating;
Severe damage to the sealing ring and dust cover of grease-sealed bearings.
Items to be inspected during operation include bearing rolling noise, vibration, temperature and lubrication status, as detailed below:
1. Bearing Rolling Noise
A sound meter is used to inspect the volume and sound quality of rolling noise generated by operating bearings. Even minor damage such as spalling on bearings will produce abnormal and irregular sounds, which can be distinguished with a sound meter.
2. Bearing Vibration
Bearings are highly sensitive to vibration-related damage. Defects including spalling, brinelling, corrosion, cracks and wear can all be reflected in bearing vibration measurements. Special bearing vibration measuring instruments (such as frequency analyzers) can measure vibration magnitude, and abnormalities can be deduced via frequency analysis.
Measured values vary depending on bearing operating conditions and sensor mounting positions. Therefore, judgment criteria shall be established after analyzing and comparing measured data of each machine in advance.
3. Bearing Temperature
Normally, the bearing temperature rises gradually after startup and reaches a stable state within 1 to 2 hours. The normal operating temperature of bearings varies with machine heat capacity, heat dissipation capacity, rotating speed and load.
Improper lubrication or incorrect installation will lead to sharp temperature rise and abnormal overheating. In such cases, operation must be stopped and necessary protective measures taken.
Thermal sensors can continuously monitor bearing operating temperature and trigger automatic alarms or shutdown when the temperature exceeds the specified limit, so as to prevent bearing burn-out accidents.
