These are key stages in the preparation of flat rolled steel for the final customer, and they are usually undertaken by service centers. The large coils produced by steelworks weigh 25 tonnes or more and are typically upwards of 1,500mm wide. Few customers can accept steel in this form, so the coils often have to be broken down into more manageable sizes.
Sometimes they are transformed into smaller, narrower coils by a combination of slitting (to reduced the width) and then cutting off a certain length of the main coil, and re-coiling this, to achieve the required size. A single coil may be slit into varying widths in one operation
Alternatively coils may be cut into sheet by removing specific lengths from the coil (cutting-to-length). This may follow a slitting operation if sheet which is narrower than the incoming coil is needed. Less frequently, coil or sheet is transformed into a large number of identical flat shapes of precise dimensions ready for direct use on a production line by the steel end customer (blanking). And for more detail click and see wikipedia entry.