Calender cutting

Note: Calender cuts and dry cuts must be differentiated.
For Machine calenders:
1. Sheet is too dry.
— reduce dryer steam.
2. Look for barring due, for example, to screens.
3. For calender cuts, pull sheet tighter in the stack.
— check spreader bar adjustment.
4. Check for a slack sheet in the dryers (wrinkles).
— check for wrinkles after machine calender.
5. Dryer felts may be too tight.
6. Check alignment and crown on rolls.
— high roll crown aggravates cutting.
7. Check calender for hot bearings.
— replace roll bearings that are dragging.
8. Ensure uniform basis weight profiles.
— thick areas cut.
9. Check for irregular wear of calender rolls.
10. Check for temperatures that are too high in calenders.
— roll over-heating contributes to cutting.
Note: Raising calender rolls can reduce cutting or reducing pressure but the sheet finish may be impaired.
For Supercalenders:
1. Check levelness of sheet going to supercalender.
— good roll condition is critical to good supercalendering.
2. Look for wrinkles in sheet leaving machine calender.
3. Check dampener operation.
— too much, too little, or uneven dampening can contribute to calender cuts.
4. An out-of-line fly roll may cause paper to wrinkle and result in a cut when pressure is applied.
— sheet can follow calender roll if fly roll is not used.
See Calender cuts.