OptiPress Center – center roll based press section - is a reliable, well-known concept that combines close to 40 years of pressing technology experience with modern shoe press technology. With this solution, a shoe press replaces a roll just before the first open draw. The resulting boost in dryness thus fully benefits web runnability in the open draw.
If necessary to meet end quality requirements, a center-roll based press can be followed by a separate roll press. In the containerboard production from recycled fiber, machines dedicated to high speeds and light basis weights can be equipped with an OptiPress Center pressing process.
There are hundreds of outstanding Valmet OptiPress Center (formerly named as SymPress) press sections operating successfully around the world in paper and containerboard production machines – for new lines and rebuilds alike. Read more about some of these customer success stories here.
OptiPress Center center-roll based press section.
Transfer belt technology allows the draw between the press and dryer sections to be closed in center roll-based concepts, too. Less draw is required, and dryness and end product qualities, such as strength and porosity, improve. Rather than a transfer belt, it is also possible to use a smooth, heated metal belt that goes around the center roll and guide stretcher roll, This metal belt technology further improves press section performance, as the increased temperature of the paper web enhances dewatering in the press nip.
Sappi's Gratkorn mill rebuilt their PM11 to improve the printing paper quality. The rebuild concept was optimized for improved formation and printability and reduced two-sidedness and validated in the series of pilot trials at Valmet facilities.
When the press section of Mondi’s Štêtí's PM5 was rebuilt, the mill had sellable sack kraft paper in just three days. With increased dryness resulting in better web runnability and less steam consumption, the mill is happy with the OptiPress concept and co-operation with Valmet
In 2015, Stora Enso converted their existing paper machine In Varkaus Mill to produce linerboard to better meet the market need for renewable packaging. PM 3 is almost like a new machine now; a combination of brand new and good, well maintained trusted technology.