Radial internal clearance or preload in mounted bearings
To optimize running accuracy and stiffness, super-precision cylindrical roller bearings should have a minimum radial internal clearance or preload after mounting. Cylindrical roller bearings with a tapered bore are generally mounted with preload.
The required operating clearance or preload depends on the speed, load, lubricant and required stiffness of the complete spindle/shaft system. The geometrical accuracy of the bearing seats also play a key role in being able to obtain the necessary clearance or preload. The operating temperature and temperature distribution within the bearing should also be taken into consideration, since a reduction in operating clearance or an increase in preload may result.