In shape rolling manufacture, a work piece will often experience different amounts of reduction in different areas of its cross section. One of the goals of roll pass design is to properly design a series of reductions in such a way as to mitigate the relative differences in shape change between areas, in order to avoid material defects. Improper reductions of the product can cause warping or cracking of the material. Metal rolling practice is not always the cause of warping or cracking, sometimes defects in the metal being rolled may be the reason.