The process material is subjected to mechanical alternating bends in the machine. The intensity of the alternating bends is reduced towards the leveling unit outlet. The higher the number of leveling rollers, the higher the number of alternating bends. General speaking: the more alternating bends, the better the leveling result. At least five rollers are required to trigger any effect at all. However, with five rollers you can achieve only a rough level of flatness. For thin material you tend to need more leveling rollers than for thick material. Experience indicates that at least 11 to 13 rolls are needed on parts leveling machines in order to achieve good tolerances.