Rolled ring forging is a special forging process that is typically performed by heating, then punching a hole in a thick, round piece of metal to create a donut shape, and then reheating, and rolling and squeezing, stretching (or in some cases, pounding) the donut into a thin ring. Ring diameters can be anywhere from a few inches to about 30 feet. High tangential strength and ductility make forged rings well-suited for torque- and pressure-resistant components, such as gears, engine bearings for aircraft, wheel bearings, couplings, rotor spacers, sealed discs and cases, flanges, pressure vessels and valve bodies.