Page 214 - Rollingbearings

B.8 Sealing, mounting and dismounting
Monitoring temperature Inspection during a • Inspection
It is important to monitor the operating tem- – Inspect the exposed external surfaces of
perature at bearing positions If the operat- machine shutdown the bearing for corrosion Inspect the
ing conditions have not been altered, a sud- bearing rings for any abnormal signs
den increase in temperature is often an When a machine is not in operation, it is an – For sealed bearings, inspect the seals
indication of developed bearing damage and opportunity to assess the condition of bear- for wear or damage
possible imminent failure of the bearing ings, seals, seal counterfaces, housings, and – Where possible, rotate the shaft very
However, keep in mind that a natural tem- lubricant A general inspection can often be slowly and feel for uneven resistance in
perature rise can last up to one or two days done by removing a housing cover or cap If the bearing; an undamaged bearing
immediately after irst machine start-up and a bearing appears to be damaged, it should turns smoothly
after each relubrication when using grease be dismounted and thoroughly inspected
Shaft and belt alignment, and a thorough • Detailed inspection of grease lubricated
Monitoring lubrication conditions inspection of the machine foundation and bearings
exterior, can also be done during a machine Grease lubricated open bearings in split
Bearings can only achieve maximum perfor- shutdown plummer blocks can be subjected to a
mance levels with adequate lubrication The Any condition, whether it is a missing shim more detailed in-situ inspection as
lubrication conditions of a bearing should or a deteriorating foundation, can negatively follows:
therefore be monitored closely The condi- affect machine performance The sooner any
tion of the lubricant itself should also be problem is identiied, the sooner corrective – Remove all grease around the bearing
assessed periodically, preferably by taking action can begin It is far less costly to replace – Remove as much grease from the bear-
samples and having them analysed bearings and associated components during ing as possible using a non-metallic
SKF recommends the following general a regularly scheduled shutdown than during – Clean the bearing with a petroleum-
scraper
Sealing, mounting and dismounting • Check for lubricant leaks in the areas sur- Inspecting bearings – Dry the bearing, and surrounding parts,
unscheduled downtime that unexpectedly
guidelines for lubrication-related inspection
activities:
takes the machine out of service
based solvent by spraying the solvent
into the bearing Rotate the shaft very
slowly while cleaning it, and continue to
spray until the solvent ceases to collect
rounding the bearing positions
• Keep protective collars and labyrinth seals
Bearings are not always easily accessible
dirt and grease For large bearings that
However, when bearings are partially or fully
illed with grease for maximum protection
contain a build-up of severely oxidized
lubricant, clean them with a strong
• Check that automatic lubricating systems
exposed, visual checks can be made The
alkaline solution containing up to 10%
most practical time to inspect bearings is
are functioning properly and providing the
during routine maintenance
caustic soda and 1% wetting agent
appropriate amount of lubricant to the
When inspecting a mounted bearing, SKF
bearings
with a lint-free cloth or clean,
guidelines:
reservoirs, and replenish as necessary
moisture-free compressed air (but do
• Where manual grease lubrication is
not rotate or spin the bearing)
employed, relubricate according to
• Preparation
B.8 • Check the lubricant level in sumps and recommends following these general – Inspect the bearing raceways, cage(s)
and rolling elements for spalls, marks,
schedule
– Clean the external surface of the
• Where oil lubrication is used, change oil machine scratches, streaks, discolouration and
according to schedule – Remove the housing cover, or the hous- mirror-like areas Where applicable,
• Always make sure that the speciied lubri- ing cap, to expose the bearing measure the radial internal clearance of
cant is used – Take lubricant samples for analysis For the bearing (to determine if wear has
oil lubrication, take samples from the taken place) and conirm that it is within
sump/reservoir For grease lubricated the expected range
open bearings, take samples from vari- – If the condition of the bearing is satis-
ous positions within the bearing and factory, apply the appropriate grease to
surroundings Inspect the condition of the bearing and the housing and imme-
the lubricant Impurities can often be diately close the housing If bearing
detected by spreading a thin layer of the damage is evident, dismount the bear-
lubricant on a sheet of paper and exam- ing and protect it from corrosion Then
ining it under a light conduct a full analysis
– Clean the exposed external surfaces of
the bearing with a lint-free cloth
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