bearing

Also:

Misalignment.

Misuse (using the machine outside its design spec.).

Misalignment is the number one reason for bearing failures. Mostley found on conveyer belt lines, blower shafts, and long power driven shafts. If your final alignment of a loaded shaft is not 100% perallel, being perpendicular to the mounting surface, even being more then 2% error, will cause a bearing failur over time.

The more "out of alignment" condition introduced into a bearing mount, to sooner you will face the failure. Some bearings will allow up to, 2mm or 3mm of being out of alignment, but not much more for a sound lifetime expenctancy of the said bearing.

Then the rest comes into the picture, lack of general maintainence, cleaning and lubrication of the bearing for continued opperational life span. Your condition of environment will determind the frequentcy of service requirements.

Maximo

preload on the bearing(s) and vibration are also factors for failure. But lubrication and alignment are the biggest factors for failure as long as the original choice of bearing was correct.

Tapered(roller) bearings and radial(ball) bearings must be selected based on load, speed(rpm), expected life cycle, environment and a number of other factors for instance sealed pre lubricated bearings vs a maintenance cycle to lubricate bearings during their life cycle.

The original design,selection of bearings and maintenance are the keys to maximizing bearing life.

Scooter

• Jerky load on shaft
• Lack of Lubrication
• Under-design for static load
• Dust/abrasive/corroding atmosphere getting in

The most prevalent reason for bearing failure is over-lubrication.

The excess grease actually increases friction and heat.

This is basic lubrication/vibration/environmental/etc. etc. stuff. There is a HUGE amount of information regarding this issue all over the internet. If you need to ask this question you should look for another line of employment or enjoyment as the case may be.

The following tells me why you would ask such a basic question ---

sajid ahmad says; "work is fine if it doesn't take much of your time"

http://en.wikipedia.org/wiki/Tribology

Good Morning Sajid Ahmad: All of the items mentioned are important factors. Monitoring, diagnosing condition and extending life are not as simple as some would think. Check out www.bearinglifeguard.com. There are a number of tutorials and references. If you need more detail contact me at john@bearinglifeguard.com. Vibes

Also consider the bearing manufacturer's rated life/load data. Bearing are rated according to B10 life, the number of revolutions that 90% of the bearings will survive. Fatigue will kill the bearing at some time, unless it is very over-specified, no matter how careful you are about alignment, contamination, lubrication, etc.

I would like to heartily agree with all of the above and add one more.

Eddy currents.

This can occur in electric motors and generators with a different potential between rotor and stator. The electricity finds the line of least resistance through the rolling elements of the bearing. This causes etching of the surface of either the rolling elements or the race rings. The reduced quality of the surface finish soon results in the destruction of the bearing.

Who the heck is Eddy??

Actually I assume you are referring to bearings in electrical equipment (motors, generators, etc.)

I hope I would NOT find Eddy currents in the wheel bearings of my pickup truck. Am I right?

Bill

How long have you been doing your job? Ha Ha

Are you real engineer man?