The objective, should be to apply an amount of grease that will replenish the bearing without causing churning, heat generation, or escape of grease into the motor’s windings. I prefer manual grease guns because an experienced lubrication technician can feel problems in motors, such as excessive back pressure, when manually greasing. This important feedback mechanism is lost when externally powered grease guns are employed. Several technologies are available to provide feedback to the lubrication technician while he is regreasing bearing. Best practices based on rule-of-thumb are
1.Vibration Analysis. When a motor bearing is properly lubricated, the vibration level is typically low. However, as the lubrication film becomes strained due to lack of grease, the bearing’s surface asperities begin to contact, which results in low amplitudes, but high-frequency physical displacement, or vibration, which alerts the lubrication technician that the bearing requires relubrication. The reestablishment of the lubrication film should reduce or eliminate the high-frequency vibrations. If the condition is not rectified, asperity contacts will become more severe and eventually produce impacts. When impacting occurs, damage to the rolling elements and or the raceways occurs, which is detectable as bearing fault defects, which normally are lower-frequency, higher-amplitude vibrations. Vibration analysis can supplement conventional calculation-based regrease interval estimates to refine motor lubrication practices.
2. Acoustic Emissions Analysis. As with vibration analysis, asperity contact caused by the initial stages of lubricant starvation also manifests in the form of acoustic emissions. Unlike vibration analysis, where the frequency of vibration produced is a function of running speed, ultrasonic acoustic emissions associated with the lack of lubrication always occur at approximately the 25 to 35 kHz frequency range. When a motor bearing requires grease, the
amplitude of the ultrasonic signal will increase, indicating a need to relubricate. When grease reaches the bearing, a reduction in the amplitude of acoustic emissions is detectable by listening with headphones. Like vibration analysis, ultrasonic analysis can be employed in conjunction with and to refine calculated relubrication intervals and to ensure that grease is reaching the bearings.
#maintenance #reliabilityengineering #petrochemical #chemical #refinery #oilandgas #chemicals #petrochemicals #mechanicalengineering # #commissioning #turnarounds #bearings #rca #fmea #epcprojects
1.Vibration Analysis. When a motor bearing is properly lubricated, the vibration level is typically low. However, as the lubrication film becomes strained due to lack of grease, the bearing’s surface asperities begin to contact, which results in low amplitudes, but high-frequency physical displacement, or vibration, which alerts the lubrication technician that the bearing requires relubrication. The reestablishment of the lubrication film should reduce or eliminate the high-frequency vibrations. If the condition is not rectified, asperity contacts will become more severe and eventually produce impacts. When impacting occurs, damage to the rolling elements and or the raceways occurs, which is detectable as bearing fault defects, which normally are lower-frequency, higher-amplitude vibrations. Vibration analysis can supplement conventional calculation-based regrease interval estimates to refine motor lubrication practices.
2. Acoustic Emissions Analysis. As with vibration analysis, asperity contact caused by the initial stages of lubricant starvation also manifests in the form of acoustic emissions. Unlike vibration analysis, where the frequency of vibration produced is a function of running speed, ultrasonic acoustic emissions associated with the lack of lubrication always occur at approximately the 25 to 35 kHz frequency range. When a motor bearing requires grease, the
amplitude of the ultrasonic signal will increase, indicating a need to relubricate. When grease reaches the bearing, a reduction in the amplitude of acoustic emissions is detectable by listening with headphones. Like vibration analysis, ultrasonic analysis can be employed in conjunction with and to refine calculated relubrication intervals and to ensure that grease is reaching the bearings.
#maintenance #reliabilityengineering #petrochemical #chemical #refinery #oilandgas #chemicals #petrochemicals #mechanicalengineering # #commissioning #turnarounds #bearings #rca #fmea #epcprojects
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