Coldrolling

Cold rolling is a metalworking process in which metal stock, typically sheet, strip, or ribbon, is passed through pairs of rolls at or near room temperature to reduce thickness and alter mechanical properties. It is widely used on materials such as carbon steel, stainless steel, aluminum, copper, and brass. The process usually starts with hot-rolled or annealed stock that is cleaned and pickled to remove oxide before rolling.

Through multiple passes in a cold-rolling mill, thickness is decreased, surface finish is improved, and dimensional tolerances are tightened. Lubricants and controlled rolling speeds are employed to manage friction and temperature. Because deformation occurs below the recrystallization temperature, the metal work hardens, increasing yield strength and hardness while reducing ductility.

To achieve specific property profiles, mills may perform intermediate annealing (stress relief) or full annealing (recrystallization) in continuous or batch lines, or apply tempering after rolling. Post-rolling processes such as skin-pass (lightly reducing) can adjust flatness and surface quality without significantly reducing ductility.

Quality considerations include tight thickness tolerances, flatness (camber and bow), and edge quality. Common defects include edge cracking, stretcher strains, and nonuniform thickness. Economic and technical factors include energy use, tooling wear, and the need for precise lubrication and handling.

Applications span automotive body panels, appliances, packaging steels (tinplate), electrical enclosures, and branded consumer goods. Cold rolling yields high-strength, fine-surface products with precise gauges, often followed by annealing or tempering to achieve the desired formability.