Bearing life is often determined by the number of hours it will take for the metal to fatigue. To better understand metal fatigue, try the following experiment. Grab a paperclip, pinch then end piece and slightly flex or pull and then release. Notice how it returns to the same position? You could repeat this process for years without breaking or “fatiguing” the metal of the paperclip. Now, grab the the paperclip and completely straighten it out, and bend it back and forth in the middle. Notice how it does not return to its original shape? The paperclip will break in half after 20-25 bend cycles because the metal has been stressed, hardened, and brittle. Metal has a memory just like rubber, and if stressed outside of that elastic range, it becomes fatigued, and will eventually fail. When a bearing is not exposed to stress, there is nothing in a bearing to wear out.
What are some commons causes of bearing stress?
- Improper Lubrication – wrong lubrication material, too much lubrication, not enough lubrication.
- Unbalanced rotation
- Bent Shafts
Any on or a combination of the above will cause a bearing to become overloaded. When a bearing is overloaded, it generates heat. Heat will cause lubricant to decrease in viscosity, and as it does, it loses the ability to support the load. It will eventually form a varnish residue that will destroy the ability of the grease to lubricate the bearing, when that happens, both moisture and solid particles are able to get into the lubricant. The introduction of moisture and solids into the lubrication is probably the most common cause of bearing failures.
If you think your bearings are failing too often, or too soon, contact us at 208-459-6351. We will work with you to determine what might be causing the bearing failure, and help implement changes that will prolong bearing life.