SEW EURODRIVE PTE. LTD.
NO.9, TUAS DRIVE 2, JURONG
Bearing
SINGAPORE 638644
TEL. (65) 68621701
Inspection and
FAX. (65) 68638112 monitoring
Progress of damage - Bearing
1 Bearing starts to show abrasive wear.
2 First spall, detected by SKF enveloped acceleration technology.
3 Spalling has developed to an extent that the damage can be detected by standard vibration
monitoring.
4 Advanced spalling causes high vibration and noise levels and an increase in operating
temperature.
5 Severe damage occurs: fatigue fracture of the bearing inner ring.
6 Catastrophic failure occurs with secondary damage to other components.
Inspection - during operation
1 Monitoring noise and vibration
2 Monitoring temperature
3 Monitoring lubrication conditions
Monitoring noise and vibration
1 A common method used to try to identify deterioration or damage in a bearing is to listen.
♦ Bearings in good condition produce a soft purring noise.
♦ Grinding, squeaking and other irregular sounds usually indicate that the bearings are in
poor condition, or that something is wrong.
2 Vibration monitoring is more thorough and allows better monitoring of bearings and rotating
equipment.
♦ Vibration monitoring is based on three fundamental facts:
● All machines vibrate.
● The onset of a mechanical problem is generally accompanied by an increase in
vibration levels.
● The nature of the fault can be determined by analyzing the vibration characteristics.
Page 1 of 4
SEW EURODRIVE PTE. LTD.
NO.9, TUAS DRIVE 2, JURONG
Bearing
SINGAPORE 638644
TEL. (65) 68621701
Inspection and
FAX. (65) 68638112 monitoring
Monitoring temperature
It is important to monitor the operating temperature at bearing positions
1 If the operating conditions have not been altered, a sudden increase in temperature is often an
indication of developed bearing damage and possible imminent failure of the bearing.
2 However, keep in mind that a natural temperature rise can last up to one or two days
immediately after first machine start-up and after each relubrication when using grease .
Monitoring lubrication conditions
1 Bearings can only achieve maximum performance levels with adequate lubrication.
2 The condition of the lubricant itself should also be assessed periodically, preferably by
taking samples and having them analyzed.
3 General guidelines for lubrication-related inspection activities:
3.1 Check for lubricant leaks in the areas surrounding the bearing positions.
3.2 Keep protective collars and labyrinth seals filled with grease for maximum protection.
3.3 Check that automatic lubricating systems are functioning properly and providing the
appropriate amount of lubricant to the bearings.
3.4 Check the lubricant level in sumps and reservoirs, and replenish as necessary.
3.5 Where manual grease lubrication is employed, relubricate according to schedule.
3.6 Where oil lubrication is used, change oil according to schedule.
3.7 Always make sure that the specified lubricant is used.
Inspection - during a machine shutdown
1 Shaft and belt alignment, and a through inspection of the machine foundation and exterior.
2 Inspection bearings
3 Inspecting seal counterfaces
Inspecting bearings
1 When bearings are partially or fully exposed, visual checks can be made.
2 General guidelines:
♦ Preparation
● Clean the external surface of the machine.
● Remove the housing cover, or the housing cap, to expose the bearing.
● Take lubricant samples for analysis.
● Impurities can often be detected by spreading a thin layer of the lubricant on a sheet of
paper and examining it under a light.
● Clean the exposed external surfaces of the bearing with a lint-free cloth.
♦ Inspection
● Inspect the exposed external surfaces of the bearing for corrosion.
● Inspect the bearing rings for any abnormal signs.
● For sealed bearings, inspect the seals for wear or damage.
● Where possible, rotate the shaft very slowly and feel for uneven resistance in the
bearing; an undamaged bearing turns smoothly.
3 Take photographs throughout the inspection process to help document the condition of the
bearing, lubricant and machine in general.
Inspecting seal counterfaces
1 When inspecting the seal counterface, also check for corrosion, shaft wear, scratches, dents,
lip wear, lip tears and so on.
♦ If corrosion is evident but not severe, use a fine wet/dry abrasive paper to remove it, and then
make sure all remnants are also removed.
♦ Worn counterface parts of the shaft can be repaired using SKF Speedi-Sleeve.
Page 2 of 4
SEW EURODRIVE PTE. LTD.
NO.9, TUAS DRIVE 2, JURONG
Bearing
SINGAPORE 638644
TEL. (65) 68621701
Inspection and
FAX. (65) 68638112 monitoring
Checking associated components
A bearing will only perform satisfactorily if the associated components have the requisite
accuracy and if the prescribed tolerances are adhered to. Therefore:
1 Remove any burrs or rust.
2 Check the dimensional and form accuracy of all associated components of the bearing
arrangement.
3 Check cylindrical shaft seats. Using a micro meter, measure in two places on the shaft seat.
Be sure to measure in four directions (below fig.). For large seats, measuring in three or four
places might be needed (Measurement report form).
4 Housing seats are usually checked in two places with an internal micrometer or other
comparable measuring gauge. Be sure to measure in four directions (above fig.). For large
seats, measuring in three or four places might be needed.
5 Record the measurement values of the shaft and bore diameters for future reference. Use the
measurement report form.
6 When measuring, it is important that the com ponents and the measuring instruments are at
the same approximate temperature.
Page 3 of 4
SEW EURODRIVE PTE. LTD.
NO.9, TUAS DRIVE 2, JURONG
Bearing
SINGAPORE 638644
TEL. (65) 68621701
Inspection and
FAX. (65) 68638112 monitoring
Measurement report form
Bearing: Bearing Locatiom:
Application:
Shaft Measurement values [mm] at place Housing Measurement values [mm] at place
Measuring
a b c d a b c d
directions
Distance L Distance L
Diameter D Diameter D
1
4
Calculated mean: (1 + 2 + 3 + 4) / 4 Calculated mean: (1 + 2 + 3 + 4) / 4
Remarks:
Date: Check by:
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