Printing Knowledge

Sheetfed Gravure.  Although almost all gravure production is on web presses, sheetfed gravure presses still exist. Sheetfed gravure is used for proofing; for printing jobs which must be printed on paper available only as sheet; for fine art reproduc…

Gravure packaging and product presses are divided into two distinct groups for light weight versus heavy weight substrates. Typical products for light weight substrates include but are not limited to flexible packaging, gift wraps, paper and foil lab…

Publication presses are designed for high speed printing high quality color publications. Typical products include magazine, Sunday newspaper magazines, catalogs, newspaper inserts, and advertising printing. The product requirements of publication gr…

Every gravure press is a custom-buit machine, designed and engineered for a specific range of products. A packaging press producing 26-inch-wide labels is identical in principle to a floor covering press printing 15--foot-wide vinyl floor coverings. …

All web-fed gravure presses start from an unwinder, which serves the purpose of unwinding a roll of substrate, deeping, keeping adequate tension on the web. The printing unit, figure 4-1, the heart of the gravure press, consists of the following comp…

Solid ink film measurement. To maintain image quality during the pressrun, the operator is concerned with the ink film thickness being printed on the paper. When ink films are too thin, the images will appear to be washed out. When ink films are prin…

Densitometry, colorimetry, and spectrophotometry are the three methods used to measure color in the graphic arts. The densitometer measures optical density. It is essentially colorblind, measuring only the level of reflectance of the transmittance of…

Dampening solutions are usually sold as concentrated solutions that are diluted with water to the proper concentration. In concentrated from, it is commonly referred to as fountain concentrate, fountain etch, or just etch. Most one-step concentrates …

The primary function of solution is to desensitize the nonimage areas of the printing plate to ink. A surface that is "desensitized to ink" is a surface that ink will not adhere to. An area sensitized to ink will accept ink readily. The dampening s…

The thickness of the ink film on the rollers is a very important consideration in printing. Typical ink film thickness on a lithographic press is 0.2~0.4 mils (0.0002~0.0004 in., or 0.005~0.010 mm), depending on the ink color and printing sequence. T…

A few important design principles are built into the inking system. Each of these helps to optimize the efficiency of the inking system for depositing an even film of ink across the entire plate image.Length of ink train. The number of rollers and th…

Waterless lithography requires a printing press that is equipped with a temperature control system, Figure 3-8. Two types of press temperature control systems are used: an ink oscillator cooling system and a plate cylinder cooling system. With the in…

The inking system, or inker, of most large sheetfed presses in Figure 3-7 usually has at least ten rollers and consists of the following parts: . Ink fountain - a pan that contains the ink supply.. Ductor or ductor roller - a transfer roller that alt…

The inking system of an offset press serves five important functions: (1) ink milling, (2) varying ink input across the system, (3) storing ink for consistent ink film thickness, (4) dampening control, and (5) keeping the plate clean. Ink milling. Th…

Generally, any press smaller than 11 x 17in. (279 x 432mm) without bearers (hardened metal tings attached to the ends of the cylinder or to the cylinder's journal) is called a small offset press or, more often, a duplicator, Figure 3-6. Duplicators …

Most sheetfed presses can print on side of the sheet in a single pass. For the other side to be printed, the entire paper pile must be turned over and the paper run through the press a second time. There is, however, a type of sheetfed press that can…

A press consisting of several printing units (each with its own inking and dampening system), a feeder, a sheet transfer system, and a delivery is called a multicolor, or multiunit press. A multicolor press can have two, four, five, six, or more prin…

Auxiliary equipment for a sheetfed press is composed of those devices that perform specialized operational functions. These devices can significantly improve print quality and increase productivity. The following auxiliary equipment may be found on a…

A printing press that uses a laser system to image plates directly on the plate cylinder is referred to as direct-imaging press. The first printing press with on-press platemaking capabilities was introduced in 1991. This two-up press was Heidelberg …

Although the three-cylinder arrangement is the most common for sheetfed presses a number of other cylinder arrangements may also be encountered. Following is a brief overview of six possible cylinder arrangements (Figure 3-2): . Two-cylinder. A speci…