Future of Calender Technology, 1998 Finishing and Converting Conference Proceedings

For paper grades demanding the highest surface qualities, soft calenders with more than the usual two nips are required despite the application of high temperatures and pressures that can be applied. This increases the capital expenditure and energy consumption of soft calenders, using the traditional single nip design, to such an extent, that their commercial viability is impaired in comparison to multi-roll systems or supercalenders.

Major developments have taken place over the past few years to improve the functionality of su-percalenders in order to meet the requirements of modern paper manufacturing, both on and off the paper machine. The components and techniques of supercalenders, machine calenders and soft calenders have been enhanced and combined in several different designs.

A new calendering quality has been achieved with the development of the new Multi-nip calender we refer to as PROSOFT. This includes a new Nip Power Management System providing the ca-pability to ensure perfect, uniform nips without faults. This new technology guaranties that all previously uncontrollable deformations of the nipped rolls which cause profile defects are eliminated. Furthermore, the shear stress transfer through the paper web in the nip is avoided, resulting in higher tensile strength of the paper and longer lifetimes of the roll covers. Such new Multi-nip calenders are well suited for both on and off machine production.