Discovering the Secrets of Proper Bearing Lubrication JAVID IQBAL SODAGAR

2. At the heart of almost every industrial facilityare electric motors, which
can render equipment inoperativeshould their rollingelement bearings
fail -an occurrencemore common than necessary due to strain resulting
from improper lubrication.
Typical causes of failure include the following:
Loss of Lubricant. If the bearingis not re greased at the appropriate
interval with the proper amount of grease, or if the oil separates from the
base thickener of the grease by overheating,loss of lubricant and
lubrication can occur and contributeto equipment failure.
Grease Incompatibility. Not all greases are compatiblewith each
other. It is important to stay with the same grease or a compatible
substitute for the life of a bearing.
Incorrect Grease. Be sure to use the correct grease for your application.
Some bearing designs and applicationsneed only non-EP or general
purpose (GP) grease while others require extreme pressure (EP) grease.
Grease Degradation. Grease hardening, chemical breakdown caused
by excessive heat, and oil separation from grease base are common types
of grease degradation.

3. Re Greasing
Proper re greasing proceduresalso play a large role in preventingbearing
failure. Followingstrict re greasing steps in the correct sequence helps to
minimizefailures:
1-Re grease a bearingwhile the motor is runningand hot, or after the
motor is removed from service and the grease is still hot. Under operational
conditions, the grease is less viscous.
2-Ensure the grease gun containsthe right lubricant for the bearings to be
re greased.
3-Clean the areas around the fill and drain fittings to ensure contaminants
are not introducedinto the bearing cavity.
4-Remove the drain fitting to allow any excess grease to escape from the
bearing.
Excess Lubrication.
This occurs mainly with open face bearings, when excess grease can cause an
excessive temperature increase in the bearings due to churning and also be
pushed back into the windings of the motor and can also cause overheating
and deterioration of the electrical insulation on the windings.

4. 7-After excessive grease has been purged, reinstall the drain plug
and clean excessive grease from the drain area.
Upon installation, monitor motor noise and vibration to establish a
baseline. At regular intervals, check these measurements; any sudden
or significant change should result in inspection of the bearing
lubrication.Motor bearingtemperatureis also a valuable analysis
tool and should be monitored and trended over time. An increasing
trend could indicatethe need to renew the grease or that the bearings
are being over greased or that a bearing needs to be replaced. Finally,
pay attentionto any high-frequency(ultrasonic)noise output or
vibration level because it may be a sign of bearing lubrication
trouble.
5-Leave the drain plug out for the duration of the re greasing process.
6-With the motor running at operating temperature, add the recommended
quantity of grease, or add slowly until it begins to move into the relief tube.
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