Inner rings type IR Type IR inner rings are the SKF standard needle roller bearing inner rings. They are made of carbon chromium bearing steel, hardened and ground. The precision-machined raceways are provided with chamfers at their ends. The chamfers ease mating with the needle roller and cage assembly or the bearing ring with needle roller set. It is advantageous to use them where needle roller and cage assemblies, drawn cup needle roller bearings with open ends or drawn cup needle roller bearings with a closed end are used but the shaft cannot be hardened and ground.