Sheet Transport
Sheet-fed printing presses and die cutters use mechanical metal fingers to hold and pull each sheet through the print cylinders or cutting stations. This functional boundary, called the press gripper margin, is a narrow unprinted strip along the leading edge of the sheet where the mechanical claws grip the paper. Because the gripper fingers must physically contact the substrate, this specific zone cannot receive any ink or varnish during the printing run.
Print Area
The size of this margin is determined by the mechanical design of the press and typically ranges from ten to fifteen millimeters. Designers must keep all essential text and images out of this area to prevent them from being obscured or omitted. Any artwork that is mistakenly placed within this band will not be printed, which can result in the rejection of the entire production batch.
Converting Constraint
Layout planners must also account for this unprinted strip when calculating the nesting of carton blanks on the sheet. While the gripper margin is necessary for sheet transport, it represents a fixed waste area that is trimmed away during the final die cutting process. Proper calculation of this margin ensures that the layout is positioned correctly on the sheet to maximize the usable print area while leaving sufficient space for the mechanical grippers.
Failure to allocate this space accurately can cause the sheet to slip during high-speed transport, leading to severe misregistration of the ink and potential damage to the press plates.
