From NTN

Pressed Steel Cages

Pressed steel cages are the most common type of cage produced by NTN. In this process, steel is formed (pressed) into the proper shape and size to fit the rolling elements, their spacing, etc. Some steel cages are pressed as a one-piece retainer while others are pressed as two separate halves and assembled to form a two-piece retainer. The assembly methods used for two-piece steel retainers are spot welds, rivets, or bent finger joints. (The bent finger joints are designed into the stamped cage halves and are created when they are folded, or bent, over each other to hold the cage together).