Calendee
PAPER MACHINE
Paper produced by the paper machine typically exhibits surface irregularities, which are generated during the sheet formation phase on the wire. These irregularities, in terms of smoothness and roughness, can be modified during subsequent processing stages using machinery equipped with Nip control systems to alter the sheet’s surface.
The machine calender is located in the final section of the paper machine, just before the pope reel. It usually consists of two rolls: the base roll is driven, while the upper roll rotates by contact. This configuration is important as it subjects the paper sheet to a compressive and frictional action, which ensures uniform thickness and achieves the desired smoothness levels.
Soft-Nip Calender
The Soft-Nip calender incorporates the latest in on-line calendering technology to achieve optimal paper finishing characteristics.
The main benefits of the Soft-Nip calender are the ability to control the following sheet properties:
• Uniformity
• Softness
• Bulk
• Surface finish
The Soft-Nip calender ensures a longer dwell time of the paper in contact with the rolls.
The standard configuration of the calender is:
• Variable crown roll in the top position
• Heated roll in the bottom position
The main parameters influencing the calendering process are:
• Nip load intensity
• Cover hardness
• Surface temperature of the bottom roll
The Nip intensity is controlled by the roll loading and unloading devices. The variable crown roll ensures uniform pressure distribution from center to edge and compensates for the total load applied by the loading system.
The applied load, in combination with the roll temperature, allows the achievement of the desired surface finish across different machine speeds.
