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. 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 termed as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is termed 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.
Introduction -Definition of rolling process
• Definition of Rolling: The process of plastically deforming metal by passing it between rolls. • Rolling is the most widely usedforming process, which provides high production and close control of final product. • The metal is subjected to high compressive stresses as a result of the friction between the rolls and the Rolling process metal surface.
rolling processes can be mainly divided into (1) hot rolling and (2) cold rolling :-
Hot rolling :- The initial breakdown of ingots into blooms and billets are generally done by Hot rolling. This is followed by further hot rolling into Plate, Sheet, Rod, Bar, Pipe, Rail.
Cold rolling:- The cold-rolling of metals has played a major role in industry by providing sheet, strip, foil with good surface finishes and increased mechanical strength with close control of product dimensions.
• Bloom is the product of first breakdown of ingot (cross sectional area > 230 cm2). • Billet is the product obtained from a further reduction by hot rolling (cross sectional area > 40x40 mm2). • Slab is the hot rolled ingot (cross sectional area > 100 cm2 and with a width ≥2 x thickness). • Plate is the product with a thickness > 6 mm. • Sheet is the product with a thickness < 6 mm and width > 600 mm. • Strip is the product with a thickness < 6 mm and width < 600 mm.