How can you get a nice creasing without cracks? How can you crease and fold sensitive digital prints, laminated or varnished sheets? A lot of factors will determine the quality of creasing.
Paper with a grammage above 150 g/m2 should be creased before folding. The most common way of creasing is the flat-bed creasing machine. The creasing should be parallel to the fibre direction of the paper, but is not always possible. The geometry of the creasing tool (2), the creasing rule (4 and the creasing pressure are crucial for achieving the best result.
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1. Creasing bar
2. Creasing tool
3. Cardboard
4. Creasing rule
5 Machine table |
The direction of folding is a very important factor. You can fold thinner sheets in direction "A" without any problem, but sometimes the direction "B" (traditional method) gives a better result. The advantage of direction "B" that it "delaminates" the layers, and the layers can slide undamaged. Unfortunately modern papers not always acting in traditional way.
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Folding direction after creasing |
If the shape of the tool and the creasing rule are not ideal for the material to crease, then the paint or the varnish cracks, or the lamination peels off.
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The paint cracks on the paper |
To achieve better crease you can use rubber instead of the creasing rule. In this way the paper follows the shape of the creasing rule, it supports the paint reducing the cracking effect. This creasing method applied for example in the
Paperfox KB-32 creasing machine.
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1. Rubber |
If the material is so sensitive that it cracks anyway, you can kiss cut the cardboard. In this way you can achieve acceptable result even if the other solutions don't work. In this way you can "crease" plastic, leather or other materials as well. Although the strength of the folding is not the best, this solution produces the flattest folding.
There are some folding samples in the following picture with a very sensitive material.
1. - The creasing made by a standard
Paperfox MBE-3 flatbed creasing machine.
2. - Creasing with rubber creasing rule with a
Paperfox KB-32 punching, creasing machine.
3. - Perforating with large tooth gap.
Paperfox R-761 Kisscutting, creasing, perforating machine.
4. - Kiss cutting with a
Paperfox R-761 Kisscutting, creasing, perforating machine.
By scoring the sheet runs through a pair of rotating tool which is much more quicker as the traditional methods. Unfortunately the cracking effect even worse than by flatbed machines.
In this case a simple solution provides the best solution. Just wrap some insulation tape on the rotating cylinder under the creasing roller and it helps similar way as the rubber creasing rule at flatbed machines. That's way you can make a perfect creasing with a
Paperfox R-761 Kisscutting, creasing, perforating machine.