Initial and formation area
The formation area plays a key role in paper production and it also influences all following production stages. That’s why the correct configuration of all elements and process parameters is fundamental.
Be it a new line or a rebuilding, all components must be carefully sized and positioned to increase the efficiency of the entire production line.
INITIAL AREA
Taking into account the delicate function performed by the box, the best configuration of the draining elements is studied for each specific box, to guarantee its installation in the most appropriate position with respect to the headbox, so to ensure adequate stock activity right from the start.
Ceramic or glass loaded polyethylene drainage elements can be used, and the box can be also provided with an automatic mechanism for horizontal adjustment of the box position in relation to the slice.
The horizontal adjustment allows the forming board box to be approached or moved away from the headbox slice in order to find the best angle of impact of the jet on the canvas and then on the forming board first element.
Drainage is achieved by gravity.
FORMATION AREA
This box has no standard configuration, as the most suitable spacing and type of drainage elements required are considered in relation to the production type.
Usually, ceramic or glass loaded polyethylene drainage elements are the best choice in this position.
The drainage elements are installed on the T-bar, so to allow an easier and precise installation and removal of elements whenever needed.
These drainage elements can be installed on hydrofoil box in the formation zone. Their purpose is to increase the activity and the turbulence of the stock to improve the paper quality by obtaining a more uniform intertwining of fibres.
The inclination angles are chosen on the basis of the speed of the machine and the grammages to be obtained and elements employed are usually ceramic or fiberglass-reinforced UHMWPE.
the height of the box can also be adjusted in vertical direction.
This box is the perfect choice for machines that operate within a wide range of paper grammages, as it allows the operator to adjust the drainage angle of each single foil, thanks to a seizing-proof rotation mechanism, from a minimum of 0° to a maximum of 4° in steps of 15’, in order to optimize drainage and the stock activity.
This type of box allows to create the optimal stock activity on the basis of speed and grammage to be obtained. Using vacuum, the wire is pulled into depressions created by plastic elements installed at a lower height than the ceramic ones; the intensity of this kind of activity may be varied by adjusting the vacuum level.
The drainage elements are installed on the T-bar, so to allow an easier and precise installation and removal of elements whenever needed.
This box comes with false air valve and vacuum gauge, so to guarantee the optimization of the drainage and the formation frequency.
An additional VRV-AF valve may be installed as well, to adjust the vacuum level inside the box in an even more accurate way.
