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Unpredicted, very rapid damage development is rare. Normally, surface damage develops slowly, over
a period of many months. These are the general guidelines for selecting the interval between periodic
readings:
•
The bearings should be checked at least once every three months.
•
The bearings in critical machinery and heavily preloaded bearings (e.g. spindle bearings) should be
measured more often than other bearings.
•
The bearings should be measured more frequently when their condition is unstable (rising or irregu-
lar readings).
•
Damaged bearings should be closely watched until they can be replaced.
This implies that one has to allow time for extra checks on bearings in dubious or bad condition.
Check stand-by equipment
Vibration and corrosion can damage the bearings in stand-by machines. Check bearing condition each
time such machines are being tested or used.
Synchronize with lubrication
It may be necessary to synchronize regreasing and measuring intervals. Grease lubricated bearings should
not be measured until they have run for approximately one hour after regreasing (except when doing a
lubrication test).
Keep in mind that bad bearing condition is often connected with lubrication problems. For grease lubri-
cated bearings, a lubrication test usually provides the final proof of bearing damage. Make sure that the
right type and quantity of grease is used.
Measuring personnel
should know about:
•
lubricant type
•
maximum quantity
•
lubricating intervals
1-3 months
several days,
one week
measure
often
Measuring intervals