Ring rolling has evolved from an art into a strictly controlled engineering process. Seamless rolled rings are produced on a variety of equipment. All give the same product - a seamless section with circumferential grain orientation. These rings generally have tangential strength and ductility, and often are less expensive to manufacture than similar closed die forgings. In sum, the ring rolling process offers homogeneous circumferential grain flow, ease of manufacture, and versatility in material, size, mass, and geometry.
In the ring rolling process, a preform is heated to forging temperature and placed over the idler (Internal) roll of the rolling machine. Pressure is applied to the wall by the main (External) roll as the ring rotates. The cross-sectional area is reduced as the inner and outer diameters are expanded. Equipment can be fully automated from billet heating through post-forge handling. Advanced ring rolling equipment can roll contours in both the inner and outer diameter of the ring, allowing for excellent weight reductions, material savings, and reduced machining cost.
There is an infinite variety of sizes into which rings can be rolled, ranging from roller bearing sleeves to rings of 25 ft in diameter with face heights of more than 80 in. Various profiles may be rolled by suitably shaping the drive and idling rolls.