Folding Board

Smoothness versus Bulk

What we normally see is that board makers know that the moisture level is important, however the machine-direction control of this variable is difficult. In clearer terms, the board producers know the optimum moisture level entering the calender to obtain the best smoothness specification. But moisture content means average moisture through the board. This is normally low moisture on the surface and higher moisture in the center of the board. So when the board producers found the right average moisture, they found ideal surface moisture. However the higher moisture in the center results in greater compression through the calender and results in a bulk reduction. This gives rise to the following question: How do you get the correct surface moisture without increasing the internal moisture? The answer to this question is to remoisture the surface just before the calender.

This remoisturizing process must form an even layer and stay on the surface layer of board because we want a fine and uniform layer of water only on the surface. Moisturizing in this way, we get the very best treatment of the surface with lower calender pressure.

VIB Systems Inc, the leading supplier of moisture profile actuators for paper and board machines, has developed a new family of spraydampening systems. The new SprayTech systems have been applied in special paper applications when surface remoisture and calendering for smoothness are required.
A very stable spray pattern with water particle sizes equal to or less than 20 microns and droplet velocities of approximately 15 meters per second guarantees a fine and uniform water layer application. The SprayTech spraydampening system achieves this by Particle Size Management (PSM). The application of water needs to be done after the last dryer cylinder and immediately before the calender to avoid water penetration in the board's body.

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VIB Systems GmbH • Am Kreuzstein 80 • 63477 Maintal • Germany • Phone: +49 6109 606-0 • Fax: +49 6109 606-160

VIB Systems, Inc. • 4661-A Hammermill Road • Tucker, GA 30084 • USA • Phone: +1 770 491 8981 • Fax: +1 770 934 5716

Qualitek VIB • 4661-A Hammermill Road • Tucker, GA 30084 • USA • Phone: +1 770 543 0180 • Fax: +1 770 543 0181