Finishing Printed Materials
Finishing encompasses the essential operations performed on printed material after it exits the press. Common procedures include cutting, folding, and gathering, while other techniques range from scoring and perforating to drilling, embossing, and die cutting.
CUTTING
Cutting divides a large sheet of paper into several smaller sheets. This process is distinct from trimming, which refers to cutting off uneven edges to make sheets square and even, such as on the three sides of a book.
Guillotine Cutter
The guillotine cutter is the most common equipment for cutting paper stock. Its knife is forced through the paper at a slight angle to produce an oblique shearing action, as shown in Figure 6-16.
A sharp blade is critical; any roughness will result in a jagged edge on the sheet, which is highly undesirable. Maintaining the blade in excellent condition is essential for quality trimming or cutting. Most facilities send cutter blades out for professional sharpening.
Figure 6-17 shows a typical guillotine cutter: a large hydraulic, power-driven model. The size of a paper cutter is defined by the maximum width of paper it can cut.
Operating a Paper Cutter
The operation of both hand-operated and power-operated cutters follows the same fundamental steps.
Safety Notes. Secure permission before using the paper cutter. Only one person should operate the machine at a time. Keep both hands away from the blade and out of its path.
Begin by moving the back fence to the desired depth of cut using the front handwheel. The distance between the blade and fence is typically shown on a measuring tape or scale built into the machine bed.
Jog (straighten) the paper and place it on the cutter bed, set against the back fence and along the left side. Place a strip of chipboard under the paper pile directly below the blade to protect the cutting stick, and another strip on top directly below the paper clamp to protect the top sheets from clamp damage.
Lower the paper clamp by turning the clamp wheel to the right until it presses the paper tightly against the bed.
Modern machines require the operator to use both hands to activate the cutter blade. Some hand-lever cutters have a safety pin that must be held with the left hand while the right pulls the lever. Others require two hands on the lever. Power cutters are equipped with dual controls for simultaneous operation.
After the cut, raise the blade and ensure it is locked in its uppermost position. Then raise the paper clamp and remove the paper pile. To trim another dimension, turn the paper and repeat the process.
Safety Note. Always adjust the paper clamp to its lowest position before leaving the cutter area. Turn off the power on hydraulic machines.
FOLDING
Folding machines range from small units handling letters or brochures to large, heavy-duty models capable of folding book and magazine signatures. A signature is a sheet folded multiple times and then trimmed to form pages. Common paper folds are illustrated in Figure 6-18.
GATHERING
Gathering is the process of assembling single sheets or signatures in sequence before binding. It can be performed manually or by machine, with machines used for this purpose called collators.
SCORING
Scoring creases heavy paper or cardboard to enable easy and smooth folding. A platen press can be adapted for this operation by locking a piece of type-high steel scoring rule with a rounded face in the chase. Remove the ink rollers, pack the platen, and position the gage pins. Feed the paper into the press as if printing; each sheet will be creased when the scoring rule strikes it.
Sustainability remains a key driver, with a growing emphasis on optimizing material usage and reducing waste throughout the post-press process.
PERFORATING
Perforating is similar to scoring. The difference is that in perforating, a series of slits or holes are punched into the paper or cardstock to facilitate tearing. An offset duplicator can be used to perforate the sheet by a perforating wheel attached to the delivery end of the machine.