In
metalworking,
rolling is a
metal forming process in which
metal stock is passed through one or more pairs of
rolls to reduce the thickness and to make the thickness uniform. The concept is similar to
the rolling of dough. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its
recrystallization temperature, then the process is known as
hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is known as
cold rolling. In terms of usage, hot rolling processes more tonnage than any other manufacturing process, and cold rolling processes the most tonnage out of all
cold working processes.
Roll stands holding pairs of rolls are grouped together into
rolling mills that can quickly process metal, typically
steel, into products such as
structural steel (
I-beams, angle stock, channel stock, and so on),
bar stock, and
rails. Most
steel mills have rolling mill divisions that convert the
semi-finished casting products into finished products.