To Calculate Roller Life, you must :
STEP 1:Enable Show Roller and Cam Lifetimes
STEP 2:Enter safety factor (CAM)
Warning: Safety Factor (Roller) =Safety Factor (Cam)2
Select a Manufacturer and Bearing Part-Number of Parameter
STEP 1: Select a Roller bearing Manufacturer
STEP 2: Select a Roller Bearing
You can see immediately the Basic Rating Life,
See L10 for Roller: Part Number
STEP 3: Enable ISO 281 Modification Factors
Enable ISO 281 Modification Factors
There are three areas in the ISO 281 Modification Factors separator.
The data allows us to calculate the and modification factors.
ISO 281 Modification Factors
There are two ways to specify the same Reliability Factor
•Recommended: Use the drop-down to select, from a standard list of reliability percentages.
The drop-down list is the standard range of Reliability Factors (90 to 99.95%), as given in ISO 281.
•Enter a Reliability Factor directly as a percentage.
In this case, we simply find the nearest Reliability Factor to the Reliability-Factors in the drop-down list.
The viscosity of the Oil (or Base Oil in a Grease) is function of its Viscosity Grade, Viscosity Index, and the Operating Temperature.
To calculate these, you must enter five parameters.
•Viscosity, , at the Temperature,
•Viscosity, , at the temperature,
•The ISO VG provides two parameters: and
•The datasheets of the Lubricating Oil or Grease should provide the Viscosity at and Viscosity at Temperatures.
•In the case of heavily loaded bearings with a high proportion of sliding contact, the temperature in the contact area of the rolling elements may be up to higher than the temperature measured on the stationary ring (without the influence of any external heat sources).
Lubrication Type and Contamination Factors
The contamination factors can be determined for the following lubrication methods:
◉Oil Filtered On-Line: Circulating oil lubrication with the oil filtered on-line before being supplied to the bearings
◉Oil Filtered Off-line: Oil bath lubrication, or circulating oil lubrication with off-line filters (or without filtration)
Oil-Mist Lubrication is not considered.
Oil Filtered On-Line
Select, in the drop-down list box, the Filtration Ratio, .
The operating, or actual, Filtration-Ratio should be as high, and if not higher, than the Filtration-Ratio you select.
• - the contamination particle size, in μm, with ISO 11171 calibration.
• - filtration ratio at contamination particle size
The designation (c) signifies that the particle counters — of particles of size — shall be APC (automatic optical single-particle counter) calibrated in accordance with ISO 11171.
Also, the oil system shall have cleanliness within the range indicated by the cleanliness code according to ISO 4406.
Oil Filtered Off-Line
Select, in the drop-down list box, the Cleanliness Codes, according to ISO 4406, that best represents the anticipated operating condition.
Select, in the drop-down list box, the Level of Contamination that best represents the anticipated operating condition.
These parameters are calculated automatically when you select a Roller, and/or enable ISO 281 factors.
Life for the seleced Roller(Cam-Follower Bearing)
Basic Rating Life,
This states that if the bearing load, , is equal to the Basic Dynamic Load Rating, , then there is a 90% reliability that the bearing will survive at least 1 million rotations, if manufactured with commonly used high quality material, of good manufacturing quality, and operating under conventional operating conditions.
Modified Rating Life,
Two factors must be calculated:
• - a factor for Reliability - see below
• - a factor calculated with a System Approach - see below
The operating life is defined as the life actually achieved by the bearing. It may differ significantly from the calculated life.
The operating life cannot be calculated!
Due to the wide variety of possible installation and operating conditions, it is not possible to precisely predetermine the operating life. The most reliable way of arriving at a close estimate is by comparison with similar applications.
Possible factors influencing the operating life