Folding machine

A folding machine is a machine used primarily for the folding of paper. Paper can be folded with either a buckle or a knife; thus, there are generally three types of folding machines: buckle folders, knife folders or a combination of these two types. Whilst buckle folding is the more popular of the two methods, knife folding is sometimes preferable. Folding machine models vary in sophistication, with machines capable of processing more complex folding jobs and unusual paper forms (in terms of density and size). Organizations required to undertake mass mail-out campaigns often employ folding machines to improve efficiency.

Buckle folders work by feeding the paper at high speeds until it can move no further; the reaction of the paper is to buckle. High friction rollers then grip the paper and push it through, folding the paper, which is squeezed between the rollers, in the process. Attached rubber provides the rollers with the required grip. The front edge of the paper is then finally placed into a "pocket"—a result of the rollers pressing together with the aid of a spring.

A knife folder works by striking the paper with a knife between two rollers. This knife is not sharp enough to cut through the paper and simply strikes and creases the paper along the line where the fold is required. Ideally, knife folding is used with thick paper, for "cross folds" (commonly employed for maps and also known as a "French fold") or if the paper has been stitched during the folding process; stitched sheets can ruin high friction rollers.

Folding machines exclusively used for folding paper are commonly referred to as paper folders. These machines are typically used for creating letter folds (C Folds) and accordion folds (Z Folds). Other commonly used folds include a half fold, fold-out, double parallel fold, gate (brochure) fold, and right angle fold.

The fold type in a buckle folder is set by adjusting folding plates. Most paper folders allow for a wide range of fold types. Right angle folds require the paper to rotate 90 degrees also known as an 8-page or a right angle. More folds can be accomplished by the use of a 16-page and 32-page unit.

Entry-level paper folders require that the folding plates be adjusted manually, with fold settings specified on the folding plates. Higher-end paper folders will electronically adjust the folding plates for added precision and convenience. Both usually have fine tuning knobs for precise adjustments.

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