L10 life is the standard way bearings are rated for fatigue: it is the life that 90 percent of a group of identical bearings will reach before the first signs of metal fatigue appear. Put the other way, 10 percent are expected to have failed by the L10 point. It is a statistic about a population, not a promise about your one bearing.
Under ISO 281, the basic rating life in millions of revolutions is L10 = (C divided by P) raised to the power p, where C is the bearing's dynamic load rating from the catalogue, P is the equivalent dynamic load actually on the bearing, and p is 3 for ball bearings and 10 divided by 3 for roller bearings. To get hours instead of revolutions, divide by the speed: at n rpm, L10 in hours is one million divided by (60 times n), multiplied by the same load ratio term.
Because the exponent is 3 for ball bearings, life is extremely sensitive to load. Double the load on a ball bearing and its L10 life falls to one eighth. Halve the load and life goes up eightfold. This is why oversizing a bearing, or removing an unnecessary load such as belt over-tension or unbalance, pays back so strongly, and why misalignment that adds load is so destructive.
Basic L10 assumes ideal conditions: clean lubrication, correct alignment, no contamination and moderate temperature. Real bearings rarely see those, which is why so many fail long before their catalogue L10. ISO 281 adds a modified rating life that multiplies L10 by factors for reliability and for lubrication and contamination, and in practice contamination and poor lubrication, not fatigue, are what kill most bearings.
Because most bearings die of causes L10 ignores, you cannot simply run to the calculated life; you have to watch the bearing. Early damage shows up first as high-frequency energy, caught by the shock pulse method, and later as rising broadband vibration measured against ISO 10816-3. The specific ways bearings fail are covered in bearing failure modes.
A monitoring platform that trends bearing vibration and shock energy turns a developing fault into a scheduled change well before the L10 statistic or a catastrophic seizure. Fabrico reads that signal from the line and routes the job automatically. Book a Fabrico demo to see it.
It is the life that 90 percent of a population of identical bearings will reach before fatigue begins, so 10 percent are expected to have failed by that point. It is a statistical rating, not a guarantee for one bearing.
L10 in millions of revolutions equals the dynamic load rating divided by the actual load, raised to the power 3 for ball bearings or 10 over 3 for roller bearings. Divide by speed to convert to hours.
Because basic L10 assumes ideal lubrication, alignment and cleanliness. In reality most bearings fail from contamination, poor lubrication or misalignment, which the basic number does not account for.
Strongly. For a ball bearing, doubling the load cuts life to one eighth, because life scales with the cube of the load ratio.
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