Finishing

Cutting Most printed items have to be cut at some stage in the finishing process — either before folding or after binding or stitching — to give a clean edge. Cutting is done on a guillotine, which consists of a large steel bed; a movable piece of steel at the back (back-gauge) used to position the paper correctly; a clamp to hold the paper firm at the point of cutting; and a very sharp, electrically-driven blade. Although guillotines are essentially very simple pieces of equipment, they can have sophisticated extras: photo-electric guards to prevent the blade coming down if the operator's hands are in the cutting area; and facilities to make them programmable by a small computer or respond to a program recorded on paper tape or magnetic cassette. In either case, the program automatically moves the back-gauge to the required position for the next cut and can save a great deal of time where there is a complex sequence of cuts to be done.

Scoring and perforating Scoring is done on board or thick grades of paper to facilitate folding. In letterpress printing scoring rule can be part of the printing forme on the press, offset, perforating rules can be stuck around or across t cylinder or scoring wheels can be brought into the operation between the printing unit and delivery of the sheets or done 01 scoring machine.

Perforating can be carried out similarly, using a perforating rule in the forme on a letterpress machine or a perforating rule wheel on an offset machine. The same separate machine used f scoring will also perforate.

Both scoring and perforating can also be done while die cutting.

Folding Where an item has been produced on a web-fed pre: the press will usually produce folded sections of 8, 16 or 32 pages. However, with sheet-fed printing, the sheet has to be folded aft printing on a folding machine. The flat sheets are fed in at one ei and the machine delivers the sections folded in accordance with the imposition scheme used. Most folding machine process 10,000 sheets an hour or more.

Folding machines fold the sheets using either a knife fold 01 buckle fold (see below), or a combination of both; most mode high-speed folders use buckle folding. Various special folds are used for pamphlets – such as concertina fold and the French

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