Jumbo presses: Increased performance with high tech roll covers

A large portion of the world's board and packaging paper continues to be produced on machines with press sections using jumbo press rolls. The installation of a shoe press would increase efficiency, but this represents a high capital investment. Typically, the jumbo press roll uses a rubber cover. The negative features of rubber are ageing after hardening, wear and bonding strength. The two main issues which affect the sheet profile and dryness are uneven wearing and age hardening of the cover, both of which will require periodic removal of the roll for grinding. The development of materials for press roll covers and their bonding systems has allowed for increased scope of application of polyurethane covers in the board and packaging sector. The high performance polyurethane material used by Voith Paper for roll covers demonstrates that the use of rubber for these high intensity jumbo press nips may be a thing of the past.