The figure shows an example of the sensors installed in a standard tandem cold rolling mill and the control functions of these sensors. A rolling mill for flat products must produce products free from camber and bends while obtaining the desired thickness and width. Thickness control is carried out by repeating a process that involves (i) measuring the strip thickness with a sensor, (ii) calculating the difference between the measured and target thicknesses, (iii) converting the difference into the desired roll gap to compensate for this difference by a static control model, and (iv) adjusting the screw-down device to this roll gap. In practice, rolling is started by setting the rolling conditions given by the model so that the target values are met. During rolling, additional control is conducted to correct by the sensors and control units the deviation of measured values from the target value. This additional control is called dynamic control. Modern rolling mills are equipped with numerous sensors and control units, in addition to the basic hardware used to support and drive the rolls. Strip thickness is adjusted by controlling the amount of rolling reduction of the work rolls, using thickness gauges as sensors installed before and after each roll stand. Control of the profile by decreasing the strip crown and edge drop is achieved by profile control units installed in the rolling mill, such as those associated with bending, shifting, or crossing the intermediate rolls and work rolls on the basis of the thickness distribution and the output of the profile detectors. In tandem mills, rolling is usually conducted with a tensile force exerted on the material. It is therefore necessary to maintain the volumetric flow rate of the material constant between the stands as well as control the tensile force. Failure to maintain the constancy will result in the strip breaking or looping between the rolling stands. For this purpose, the rotational speed of the rolls is controlled based on the results of strip speed measurement. In recent hot rolling practice, it has become common to carry out controlled rolling, for achieving required microstructure by controlling the temperature of the material being rolled for controlled cooling in accordance with measured temperatures.