Confirm the change before assigning a cause
If a report shows a three-point press-dryness drop, first confirm sampling location, instrument, grade, basis weight, speed and whether the comparison periods are equivalent. Do not apply a universal steam-conversion factor; the dryer response depends on the machine energy balance.
Check in a controlled sequence
- Review the cross-machine dryness and moisture profile, not only one average value.
- Inspect felt surface, seam, edges, compaction, contamination, permeability trend and water removal.
- Verify showers, nozzles, oscillation and water quality against the approved felt and machine settings.
- Check uhle box, vacuum, seals and piping against the machine baseline.
- Confirm nip load, roll cover and surface, alignment and felt tension from approved specifications.
- Review furnish, filler, retention chemistry, temperature and other process changes.
Use the timing of the change as evidence
A sudden change points toward measurement, process or mechanical events that occurred at the same time. A gradual trend may involve contamination, compaction, wear or slowly changing process conditions. Neither pattern proves that the felt alone is responsible.
Record one corrective action at a time and compare press dryness, profile, breaks, vacuum water removal and downstream steam per ton with the baseline.
