What is the main cause of bearing problems?

boor lubrication due to oil quality, defect at lubricant system, delay or negation  of routine maintenance, overload, engine harshing with over speed, boor cooling for lubrcant.

Maintenance not performing on time.

Apply suitable grade lubricant and fixing as per procedure.

Replace the the baring as per service  owner manual duration.

there are more Problems but the main Problem is Friction and Bad Method of lubrication ..... Bearing May work out of the Limited Speed that affect Badly on it

Insufficoent / improper lubrication

Damaged oil seal / dust formation

Miasalignment

Manufacturing defect

running out of rpm

Excessive loads

Corrosion

Cause of bearing damages is no grease and long time uses.

non lubricating

oil seal damaged& dust forming

alignment problem

manufacture fault  while assembling

running out of specified rpm

over driven

1. Improper Load Distribution 

2. Lub oil distribution system failure (even in particular bearing)

3. Contamination of Lubrication oil

4. Damage in the shaft / pin.

5. Un-noticed Hot spot in the bearing

1. Excessive loads
2. Insufficient lubrication 
3. Improper Assembling
4. Misalignment
5. Improper Torque used
6. Contaminated Lubrication
7. Corrosion

excess loads

lubrication defect

not proper mount

alignment not done properly

low quality materials used

Improper lubrication is the major cause of bearing failure.

1\\   Dirt in lubrication system or in bearing back itself

2\\Oil starvation

3\\Misassemble

4\\Improper machining of components (shaft, housing ant etc)

5\\Overloading

6\\Corrosion

7\\cavitation