Rullimine

Rullimine is a mechanical forming process in which a workpiece is passed between rotating rollers to reduce its thickness and alter its shape, producing sheets, strips, foils and other profiles. In Estonian usage, the term covers metal, plastics and paper processing, and it is widely applied in industrial manufacturing.

In hot rolling, the workpiece is heated above its recrystallization temperature to allow large reductions and initial shaping. This can create surface scale and residual stresses, and subsequent heat treatment or finishing may be needed. Cold rolling is performed near room temperature to achieve a smoother surface, tighter tolerances and increased strength through work hardening. Lubrication and precise temperature or tension control are important in both variants, and intermediate annealing is sometimes used to restore ductility during heavy reductions.

Equipment commonly used for rullimine includes rolling mills with multiple stands and precision rollers, sometimes arranged as tandem mills for continuous production. For certain materials and finishes, calenders—machines with a stack of rollers—are used instead of or in addition to standard rolling mills, notably in paper and some plastics processing.

Applications encompass metal products such as steel and aluminum sheets, strips and plates; packaging foil; automotive components; and various polymer or composite sheets. Rullimine also plays a key role in fabricating electrical conductors and components requiring tight thickness control and surface finish.

Historically, rolling has been a fundamental forming method since the early modern period, with significant development in the 18th and 19th centuries that enabled mass production of metal sheets. Modern rullimine emphasizes process automation, control systems and energy-efficient practices to improve material properties and productivity.