What is a fold break?

A fold break is a defect in a folded printed product caused by the loss of the print substrate’s malleability, which is necessary for folding.

If the fold runs across a printed area, the break or torn line becomes visible to a greater or lesser extent, causing disruption and reducing quality.

To ensure a smooth folding process, it is essential to crease the paper in advance at the point where the fold is to be made.

To create a hinge-like, flexible zone in the cardboard sheet, creasing should be carried out on coated card with a basis weight of 150 g/m² or higher. During subsequent folding by 90 or 180 degrees, the linear deformation of the crease in the printed material prepares the fold line, preventing breakage or tear-out.

Cardboard with a higher proportion of coated surface is more prone to fold failure if the creasing has not been carried out correctly. The optimal fold runs parallel to the grain direction, but in folding box production, folding is also carried out against the grain direction. This makes correct creasing all the more important.

In post-press processing and for the correct use of creasing tools, appropriate formulas and tried-and-tested guidelines for the thickness of the cardboard to be creased are applied. The crease channel and the crease line width are usually selected depending on the thickness of the cardboard. It is important that all edges of the creasing tools are blunt.

Possible causes of fold breakage could include incorrect tools that are not suited to the material, or the creasing setup. The problem can also arise if the printed material suffers significant moisture loss due to high-intensity radiant heat drying.

By optimising all parameters to suit the various types of cardboard, creasing is the necessary technical prerequisite for a smooth fold without fold breakage.