Lesson plan
DN factor
DN factor, also called DN Value, is a number that is used to determine the correct base oil viscosity for the lubrication of various types of bearings. It can also be used to determine if a bearing is the correct choice for use in a given application. It is a product of bearing diameter (D) and speed (N). D = diameter (in millimeters) of the bearing in question. For most types of bearings, there are actually two required measurements: the inner diameter and outer diameter. In such cases, D = (A+B)/2, where A = inner diameter and B = outer diameter. The sum of these two values is then divided by 2 to obtain the median diameter, sometimes also called pitch diameter. N = bearing speed. This is the maximum amount of revolutions per minute (RPM) that the bearing will move. The DN factor of a bearing is obtained by multiplying the median diameter (A + B)/2 by RPM, and sometimes by a correction factor. This correction factor may vary from manufacturer to manufacturer. No consensus exists among tribologists as to a constant correction factor across manufacturers.
Article summary
DN factor, also called DN Value, is a number that is used to determine the correct base oil viscosity for the lubrication of various types of bearings. It can also be used to determine if a bearing is the correct choice for use in a given application. It is a product of bearing diameter (D) and speed (N). D = diameter (in millimeters) of the bearing in question. For most types of bearings, there are actually two required measurements: the inner diameter and outer diameter. In such cases, D = (A+B)/2, where A = inner diameter and B = outer diameter. The sum of these two values is then divided by 2 to obtain the median diameter, sometimes also called pitch diameter. N = bearing speed. This is the maximum amount of revolutions per minute (RPM) that the bearing will move. The DN factor of a bearing is obtained by multiplying the median diameter (A + B)/2 by RPM, and sometimes by a correction factor. This correction factor may vary from manufacturer to manufacturer. No consensus exists among tribologists as to a constant correction factor across manufacturers.
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