Lube related squeal at low bearing temperatures

[return1874]

Why is their a squeal in oil impregnated sintered bronze bearings (material B-910) at -30 deg. F when no squeal occurs when the oil lubricant is left out?

 

[diamondjim]

I would think the oil is expanding at this
low temperature and acting as a brake. Do
you see an increase in torque? If particles
in the oil are not freezing and expanding,
I have no other explanation. What kind of
oil are you using?

 

[return1874]

diamondjim,

Thanks for the response. Water may be present in the bearing and could be expanding when freezing causing a braking action. Higher current draw and slow motor starting accompanies the squeal while these symptoms are not apparent in the dry, no-squeal bearings.

 

[electricpete]

sorry if I may be way out in left field....

As you know viscosity decreases with temperature. Is it possible your viscosity is way too low for the clearnaces within this bearing?

 

[electricpete]

you know what I meant.... viscosity increases with lowering temperature. Is it possible your viscosity is too high?

 

[plasgears]

Have you looked at thermal interaction of the shaft to the bearing? The shaft may be relatively larger than the bearing depending on the relative thermal expansion coeff. If the bearing shrinks more than the shaft at temp, there is your problem.