subject: Ball Bearing : Life Expectancy And Related Issues [print this page] The user of a bearing is the only person who can determine the expected life of a ball bearing. This calculated life of the bearings is known as the L10 life of bearing. The life expectancy of bearings is calculated by assuming that before experiencing any kind of metal fatigue, the bearings would make a certain amount of revolutions. Here, fatigue refers to the eventual breakdown of metals or gradual weakening of it due to constant strain. Now, because the manufacturer who is using the bearings best knows the operating environment of the place where bearings are installed, he only can determine the right duration of L10 or the life expectancy of bearings.
L10 is determined using the the following factors:
-The material with which bearings is made up of
-The pressure being put on the bearing (stress)
-The number of times the load cycle takes place for the bearing material
Though at times the bearing do not stretch up to the expected life period and experience premature failure. The two most likely reasons for it are :
-Bearing lubricant exposed to water or moisture
-Excess of lubrication leading to high heat
Moisture in bearing lubricant
Water or moisture are extremely unfit for bearings. Moisture as minimum as 0.002 percent within bearing oil can reduce the bearing life by as much as 48 percent at one go. Generally, the water enters the bearing case through packaging leakage, cooling temperature within the case or moisture ladened air. In fact if we go by the statistics then 6 percent of water content is enough for reducing the bearing life by 83 percent straight away. Thus the three main sources identified for the contamination of bearings are :
-Leakage through packing
-Washed down hoses
-Moisture within the bearing case
Excessive heat due to excess of lubricant
The problem with too much of lubrication is The bearing consumes too much of energy as it moves through the lubricant. This energy heats up the lubricant resulting in the depletion of its viscosity and later, making the lubricant to form solids in as varnish and coke.
by: sanchita
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