Surface roughness of bearing seats
The surface roughness of a bearing seat does not have the same degree of influence on bearing performance as the dimensional and geometrical tolerances of the seat. However, obtaining a desired interference fit depends on the roughness of the mating surfaces, which is directly proportional to fit accuracy. For less critical bearing arrangements a relatively rough surface finish is permitted.
Guideline values for the mean surface roughness Ra are listed in table 1 for different bearing seat tolerance grades. These recommendations apply to ground seats, which are normally assumed for shaft seats.