flushing of bearings with oil 3

[marvelmaker]

I know it depends on the bearing type itself, but take for example a standard overhung load adaptor with tapered roller bearings, is there a general rule of thumb as far as additive lifetime when case flushing with oil is added to improve bearing lifetime.

 

[marvelmaker]

I guess my question is not clear.

Can we predict how much lifetime case flushing will add to bearing lifetime?

I appreciate that bearing lifetime calculations are based on an L10 rating, which means that 90% of the bearings will achieve the lifetime based on the calculations. There are many factors in the calculation, speed, temperature, pressure, etc.

Has there been any significant research done to see if there is correlation, or is there a way to add the effects of case flushing into an L10 bearing lifetime calculation, in order to account for this added cooling?

 

[jmoritz]

Not 100% sure what "case flushing" is but the major bearing companies all have La23 life calculations that consider the effect of lubrication film thickness on bearing life. Most have advanced calculations that consider the effects of particle contamination, considering the effects of a filtration system with oil circulation on bearing life as well.

There are no guidelines or rules of thumb to life improvement with different lubricating techniques. The thermal effects of different lubrication techniques can be calculated -- that's a good indicator of the bearing's performance under the outlined operating conditions.

Every bearing calculation is different and yes, theoretical. It is impossible to predict the life of any particular bearing.

 

[Hippo41]

Agree with jmoritz. Bearing company data that modifies the expected life of bearings is statistical only - you need a large sample to prove anything.

However, clean oil will definitely prolong the life of bearings. Is it feasible for you to monitor oil condition and flush only when necessary? That would possibly be more effective?

Lester Milton
Telford, Shropshire, UK

 

[Carburize]

marvelmaker - take a look at ISO 4406 and the associated filtration standard ISO 4572 these give methods for adjusting bearing life as a function of oil cleanliness.

 

[marvelmaker]

Thanks for the feedback, everyone, case flushing means hot oil flushing or in the case of hydraulics, running case oil through the bearing package around the shaft of the hydraulic piece of equipment, to use the case oil for lubrication and for cooling.

I am not so much concerned about oil cleanliness, but perhaps only because I neglected to think about the fact that flushing the bearing brings fresh, filtered oil to the bearing package as well, flushes out the wear particles in the process. Thanks for reminding me.

I believe my question is answered, appreciate all your help!