The primary objectives of pressing are to remove water and consolidate the sheet.
Other objectives are, to provide surface smoothness, reduce bulk and to provide as high a wet web strength as possible. These latter objectives will of course depend on the product requirements.
The pressing operation is in effect a continuation of the water removal process that started on the wire. It is far more economical to remove water by mechanical means than it is by suction (on the wire) and evaporation (in the dryers), so the methods of making the press section more efficient should always of the utmost priority.
Water removal should be uniform across the width of the sheet so that the pressed sheet has a level moisture profile entering the dryer section. Sheet consolidation is also a crucial part of the pressing operation because it is here that the fibres are forced into intimate contact so that the wet web strength is substantially increased and that good fibre to fibre bonding develops during drying.
In this section we will be looking at why we press as well as all aspects of the process of pressing. This will include
- The press roll and its evolution
- The press section and its evolution
View my short video about pressing on You Tube by clicking on the link below
Pages in category "Pressing"
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