Folding card stock is traditionally a more difficult process than folding standard text weight stock. Traditional table top paper folders have small rollers that use spring loaded tension to separate the rollers based on sheet thickness or floor models use a caliper spacing (see picture). Traditional folders have a capacity of about 8 point card stock and this is often pushing the limits of the units.

 

The three major problems experienced when folding card stock are:

 

1.  Curl of the paper when folded: Imagine a sheet of paper being wrapped tightly around a pencil, this is essentially what you find when trying to fold card paper around rollers in a traditional folder. If you are able to pass the work through the traditional rollers of the unit it will have a distinct bend to it
2. Cracking: While not new to digital printing specifically, cracking on heavy weight paper has long been an issue for printers. When we fold a sheet of printed card stock we notice that along the spine the toner or ink will split and we will be able to see the white paper beneath ruining all the hard design work put into the original plan. See our article about cracking for more information.
3.  Marking: When we attempt to feed thicker paper through a folder the thicker paper can rub against the steel rails of a buckle style fold pate, rollers or delivery guides more than a lighter paper weight would. This can leave streaks through your work, especially when you have full dark colour coverage on the job.

 

Given that these issues occur manufacturers have come out with a variety of work around options for printers. The common way to fold card stock on a longer print runs is to use a folder with a right angle. You would use a scoring wheel and a knife folder. The knife folder has oversized rollers does not use the traditional buckle plate folding style thus solving the curl problem, the scoring wheel helps somewhat with the cracking problem but is not the ideal solution. The setup for these systems can take between 30minutes to an hour or more depending on the configuration.

 

Given the constraints of digital printing manufacturers such as Morgana System and Duplo have products like the Morgana DigiFold PRO and Duplo 645/615/445 IFS, to crease inline and then knife fold the product.  Creasing eliminates the cracking problem and the knife folders over larger rollers limits the curl, these systems also minimize the amount of contact the paper makes with steel in order to limit marking on prints as well. These systems are all in one and setup digitally making it very easy to change over from job to job while producing a crack free and curl free finished product.