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Fogra folding device FI

The Fogra FI Folding Device is a device for the production of sample folds, particularly on paper.

FIWith the help of a subsequent tensile strength test on a tensile testing apparatus, the residual strength of the specifically folded sample can be determined. The residual tensile strength characterizes the strength of the fold, for example following the heat treatment of paper (drying in web offset). Different grades of paper can be compared in this way. The results are of interest for paper production and printers.

The Fogra FI has been developed on the principle of the web folder of an offset press. The device has been designed so that the size of the paper sample matches the strips tested in the Prüfbau test printing device and the Fogra Hot & IR.

Please click on the picture to enlarge it.


Functional principle

The folding device essentially consists of two movable rollers arranged in parallel. By turning a disc that adjusts the force it is possible to achieve the desired folding force between the two rollers. The required force is generated by a spring system and a lever mechanism. In order to ensure a problem-free insertion of the samples into the folder nip it is best to use paper strips that have already been pre-folded but not sharply creased. The pre-folding is carried out on a pre-folder that consists of a small lay out table, a height adjustable screw and a pre-folder roller.