We were discussing bearing removal and cleaning procedure and also we have seen the bearing installation procedure. Today we
will see here the basic importance of lubrication for smooth operation of a
bearing and also types of lubrication usually preferred in industries.
Let us see first the various important functions of
lubricant for a better performance of a bearing.
- Reduction of wear tear and friction
- Dissipation of heat
- Providing protective layer against dust and corrosion
Reduction of wear tear and friction
As we know that bearing will have inner ring, outer
ring and rolling elements i.e. balls or rollers. During operation of bearings,
there will be continuous rubbing action or wear-tear between moving parts of
bearings. Due to these rubbing actions, there will be produced friction between
moving parts.
If bearings are used under heavy load with high
speed applications, in that case lots of friction will be created and hence it
will lead the wear of surfaces of bearing parts. Therefore internal clearance
of bearings will be increased and further premature failure of bearing will be
there.
If we run the equipment under damage bearing, it
will also damage the bearing seat on shaft and bearing seat in the housing
bore.
Healthy lubrication practices of respective bearings
will eliminate the creation of friction by providing the smooth relative motion
between bearing parts and therefore it will also save the bearing housing and
shaft and we will secure the better service life of respective bearings.
For more information about the importance of
lubrication in bearing operation, please refer the post “8 ways to prevent bearing failures”.
Dissipation of heat
Friction will be created, if lubricants are not
provided, due to continuous rubbing actions between moving parts of bearings.
Friction between moving parts of bearings will develop the heat and therefore
it will lead the premature failure of moving parts of bearings and further
shaft and housing also.
Healthy lubrication practices of respective bearings
will avoid the temperature to reach at a point at which bearing parts might be affected.
Providing protective layer against dust and corrosion
Bearings will not work properly if moisture, dust or
any other foreign particle got inserted inside the bearings as dust, moisture or
foreign particle will corrode the bearing parts and further will restrict the
bearing to work properly and therefore premature failure of bearing will be
there.
There is no use of bearings those are affected due
to corrosion and therefore bearings will be protected by layer of lubricant
just since it is manufactured. Before packaging the bearings, layer of suitable
lubricants will be applied over the surface of bearing parts by the
manufacturer for avoiding the effect of corrosion.
We must note it here that during installation of
bearings, we should never remove the layer of lubricant from the surface of
bearing parts as these layers are provided for avoiding the damaging of
bearings.
Type of lubricants
Selection of suitable lubricants depend on various
factors such as type of bearing, operating temperature , operating speed, type
of bearing housing, load and working nature of bearings. We must follow the
lubricants as per recommendation of manufacturer of equipments.
However, there are two basic types of lubricants
those are usually used in industries i.e. oil and grease.
Grease will be used as lubricant in most of
engineering applications. But there are some critical applications where load
and speed, both will be high and we need to dissipate the heat generated continuously
for securing the smooth performance of our equipments. Oil lubrication systems
are usually preferred for such applications.
We can see the application of bearings those are oil
lubricated in steel shredder equipment. There will be a rotor in shredder
machine and it will run at higher speed for example 600 to 800 rpm. Rotor will
be supported by two bearings at both ends and these bearings will be oil
lubricated.
A separate lubrication system will be provided to these bearings,
where oil will be circulated continuously through the bearings. Heated oil will
pass through the cross flow type of heat exchanger, where it will be cooled and
again will pass through the bearings for dissipating the generated heat.
Do you have suggestions? Please provide your suggestions.
Reference: SKF Bearing Maintenance manuals
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