Defined by ISO Standard 5753-1981 ANSI Standard 20, internal clearance refers to the total distance one bearing ring moves relative to the other – radially or axially. Mounted and un-mounted clearance measurements will differ. This is due to interference fits that could occur between shafts and bearing bore as well as the housing and bearing outside diameter.
Bearing life is maximized when mounted clearance is 0 or slightly negative at operating conditions. Initial bearing clearance is chosen during the design or testing process to achieve maximum bearing life. More information on RBI Bearing’s Radial Ball Bearing Internal Clearances can be found here in the following chart.