Problem in Bearing Assembly

How do you know it's excessive? I've seen bearings have to be cooled with cold water lines. How big and how fast?

Heating is a balance result between the generated heat due to different frictions in the bearing and its capacity to evacuate heat to ambient air or to supporting structure.

Heat can be generated by friction in oil due to too intensive shearing between balls, ring and oil in bath. This happens often if the oil level is too high with respect to manufacturer's indications.

Heat can be generated by a wrong assembly inducing in the bearing excessive loads due to misalignment, loads in excess of oil portant capacity lead to a drastic increase of friction in rolling or even to sliding of balls/rollers.

Some times the housing is not tightened enough or the assembly surfaces are to dirty or not plane enough so that heat cannot be evacuated by conduction to structure.

Depending on the bearing design (housing, assembly,...) heat transfer via conduction to supporting structure can be many times more important than convection to air or conduction via shaft. If the oil viscosity allows still a elastohydrodynamic lubrication the bearing will perform correctly if not the risk of a quick failure is real.

All serious bearing manufacturers give in their catalogues step by step detailed indications for assembly. If those are followed no problem occurs.

Have you checked to see if the pillow block has a match marking on them and are they the same. Pillow blocks are built with both halves together and can NOT be interchanged. Your internal clearance of your bearing might be reduced by anything such as, rust, grease or a slight out of round. Check your clearance by a feeler gauge, lead strips or plastigage. Normal clearance should be around 0.0005" (half a thou). You could shim between the two halves to increase the clearance to see if this is the problem.

Good evening friend,

exessive heating means howmuch.allowable limit is ambient + 40 deg(by rule of thumb).if your bearing block heat goes beyond this limit,then the reasons may be,

excessive oil in the block

high viscous oil

excessive bearing skew result in high friction and increased heat

block id less than bearing od and vice versa

bearing ball to outer race clearance is too small

mis alignment.in these any one reason may be for excesseve heating.

first you check the oil level.ensure your oil is correct viscosity grade or not.check the bearing od with respect to block id by blue match or lead wire imprgnated method. if the gap between bearing outer race and block is too large or small result vibration and heat.check the clearance between ball and outer race. if it is too low result will be heat.check the mis alignment by dial indicator .

This requires lot of inputs from your end.

Can you pls. tell how much heat is generated on the plummerblock and in how much time the temperature is reached to peak level. What are the details of lubricant, bearing details, application, and type of load (whether any shock loads). Is the problem from the begining or it has occured after replacement of bearing.

Pls. Check up Plummer block and Shaft dimensions for the tolerances and roundness.

I don't use oil lubricated ones at work here but have quite a few greased pedestal/pillow block bearings. Overgreasing will cause them to run hot, as will undergreasing them. If it's a new bearing, it's not unusual for it to run as high as 215-225 degrees during breakin period either.

°F or °C ?