Press rolls in paper machines are crowned to achieve a uniform nip contact over the entire face of the roll under a given nip pressure. The amount of crowning depends on the roll body and cover, the deflection of the roll and the nip pressure range.
over time the roll cover will wear, changing the crowning profile
over time the elastic properties of the roll cover will change
producing at higher speeds usually means higher press loads and changed dynamic deflection of the rolls
a change in crowning of the engaging roll has a strong effect on the mating roll
Feltest products to check the press load of paper machines:
Fuji Pressure Sensitive Film – obtain detailed information on the length, width and pressure variations of the nip.
Advanced Analysis of Fuji Film – convert the information from the Fuji film into a clear, full width profile of the press.