Up & Running articles
Up & Running articles
-
Field Report - Dynamic balancing of rolls
Although a roll is statically balanced, it may have an eccentric center of gravity which cannot be detected by simple static balance. This will become noticeable when the roll speed is increased, and an end-for-end motion occurs. Dynamic unbalance requires investigation to determine which end, or both, require counter-weighting.
-
Field Report - Roll structure analysis (wound-in tension)
Among the most important factors determining the quality of a finished paper roll is consistent roll structure. Wound-in tension is the most important component of roll structure. The WIT-WOT and Gap Test are methods of measuring wound-in tension.
-
Field Report - Suction roll packing strip grooving, a case study
A paperboard mill suffered from unexplained grooving in the suction and couch rolls and sealing strips. The fog shower was identified as a culprit.
-
Field Report - Measuring fourdrinier table stock activity
On fourdrinier forming sections, stock activity on the table is necessary to improve sheet formation and drainage rate. Too much or too little turbulence causes poor formation. Forming table activity can be observed with the use of a high frequency strobe light.
-
Field Report - Improving suction roll performance
To optimize the efficiency of and ensure the best return on a suction roll investment, mill maintenance departments should follow some basic guidelines.
-
Field Report - Reel rebuild reduces waste, a case study
A coated board mill reduced bottom waste at the reel, and increased board quality, with a rebuild from pneumatic to hydraulic reel control.
-
Field Report - Function and setup of size press sealing blade
Properly functioning sealing blades in a metered size press prevent air from entering the application chamber while lubricating the blade tip/applicator roll interface. Periodic checks of the blade setup are essential for a long and trouble-free blade lifetime.
-
Field Report - Forming fabric ridging problem, a case study
Distortions in fabrics, such as ridges, cause basis weight profile problems. In this case study, the culprit was found to be a tiny speck of rust - which created a large and expensive problem.
-
iRoll Temperature examples and case studies
Valmet iRoll Temperature is an online tool for measuring the temperature profiles of rolls, roll covers and paper webs. These three case studies describe how iRoll technology has helped mills reduce roll cover wear, eliminate cover failure and improve profiles and runnability.
-
Field Report - Improving rope runs, a case study
In this case study, two paper machines were rebuilt to improve their rope runs. The rope systems were made much more reliable by making a minimum of changes. Valmet changed the transfer philosophy from tear-off to tail-release. The results were less fouling of return runs and less debris.