Common Folding Problems | Printing

Despite advances in automation folding can still be problematic for even the most experienced operators. Here is a list of some common folding problems and different ways to fix them.

Scoring

When something is scored a weakened line is created where the fold is going to be. Without a scored line you run the risk of creating irregular folds. Problems with right-angle folds are commonly caused by not scoring the paper before it enters the right angle.

Perforating

Choosing the right blades is very important. A large tooth blade will allow air to escape when folding the signatures for books, and finer tooth blades are normally used for tear-off items. To ensure that you get a clean cut the perforator blade must be placed against a lower anvil, and not using a stripper mounted above will cause the paper to wrap around the slitter shaft. Another common issue with perforation is curved perforation which can result if the pullout tires are not placed close to the perforator blade and at each edge of the sheet.

Slitting

Removing an edge or center trim of paper requires a stripper so that paper scraps can be diverted to a recycling bin. One of the issues that you can run into if the slitting blade(s) and stripper are not mounted correctly is that the paper waste will travel with the finished product onto the delivery stack.

Trapping air

Some folds require a double-parallel or letter fold in the first folder and then a right angle to a double-parallel or letter fold in the right-angle folder. This type of fold can trap air — to relieve this, make the fold in the first folder an accordion or “Z” fold.

Proper gap between sheets

Many paper jams are caused by not leaving the proper space or gap between sheets on the register table or cross carrier. A gap of one inch to two inches will accommodate most common letter and half folds folded short length into the plates. When folding longer than half of the sheet length, a longer gap is needed to allow the sheet in front to get out of the path of the sheet coming in from behind. When folding a letter fold going deep into the first plate, at least one panel length of the letter fold should be used for the gap.

Roller gap settings

The easiest concept to remember is that the tailing-edge thickness that passes through the fold roller is the paper thickness that is to be inserted in the gap set lever. Too many thicknesses in a gap set will allow the paper to slip and lose drive in the folder. Too few can mark the paper from too much roller pressure.