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.
needle 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.
Inner rings, precision machined
In inner rings IR, the raceway is precision machined. Chamfers on the end faces allow easy insertion into the bearings and prevent damage to the seal lips of the bearings. The inner rings are available with and without a lubrication hole.
Inner rings, ground
In inner rings LR, the raceway is ground. The end faces are turned and the edges are broken. These rings have larger tolerances than the rings of series IR. They are therefore suitable for applications that permit larger tolerances for width and less demanding requirements for axial runout.