Inner rings are made from hardened rolling bearing steel and have precision machined or ground raceways.
They are used where:
the shaft cannot be used as a raceway with needle roller and
cage assemblies, drawn cup needle roller bearings with open ends, drawn
cup needle roller bearings with closed end and needle roller bearings
roller bearings must be combined with wider inner rings in order to
facilitate axial displacement of the shaft in relation to the housing
optimum running surfaces are required for the seal lips.