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Winding principles part 3 - drum torque control methods, summary

When web tension and drum nip pressure are constant, drum torque will assure uniform or diminishing roll hardness from the core toward the outside of the rolls.

Winding principles part 2 - effect and elements of nip pressure

The relationship between rider roll pressure and shipping roll hardness is neither simple nor direct. This second article in the Winding Principles series explores the interrelationship between rider roll pressure, relief pressure, roll weight and nip load.

Excellent results with suction box showering, rebuild case study

A newsprint mill in southern USA was losing suction in one of their suction couch rolls. A Valmet rebuild resulted in two years of run time with very little internal pulp buildup or seal strip wear.

Overview and troubleshooting of size press threading system

This article presents an example multiple-device threading system, briefly describing each device, and then lists methods to troubleshoot the threading system.

Vibration monitoring and analysis in tri-nip press, case study

A paper machine experienced vibration in its tri-nip press on the tending side only. Valmet condition monitoring and vibration analysis used synchronous time averaging (STA) to assist in solving the problem.

Spreader roll reconditioning and upgrades optimize performance

Valmet spreader roll reconditioning service leads to a clear increase in service intervals and cuts overall maintenance costs. In addition to keeping spreader rolls in excellent condition, the spreader roll service ensures optimized roll performance, improved end product quality and reliable, wrinkle-free runs.

Floor protection in recovery boilers with decanting floors

Optimizing both the floor protection methods and materials and the cooling, washing and cleaning practices can yield significant savings in mill outage time and corresponding increases in mill production and reduced risk of mechanical damage due to mechanical cleaning or hydro blasting during floor cleaning.

Keys to optimize drying efficiency; start with the felt tension

Increased felt tension can optimize drying efficiency and improve paper quality. However, a thorough evaluation of machinery and close monitoring of felt tension, along with a complete maintenance program, are the keys to a headache-free dryer section.

Dynamic roll balancing - why, how, measurement and specification

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.

Reel primary arm nip relief methods reduce bottom waste at turnup

Excessive bottom waste occurs during turn-ups where there is insufficient primary arm nip relief at the reel. To avoid this, primary arm nip force control should start before turn-up and continue smoothly as the building parent reel travels down along the reel drum to the secondary arms at the kickout rails.