"Lithographic printing" and "offset printing" have the same meaning. This printing method is to transfer the ink on the rubber surface to the paper through a roller rubber stamp. Because the rubber surface is flat and there are no concave patterns, the patterns and patterns printed on paper are also flat, with no three-dimensional effect and poor anti-counterfeiting performance. Offset printing needs less ink, and the manufacturing cost of the mold is lower than that of gravure.

British Taglio Publishing House

When printing, the printing plate cylinder is inked on the whole page, and the ink in the blank part of the page is scraped off with a scraper, leaving the ink in the graphic part. Then the ink passes through the paper and is imprinted on the back of the paper by impression cylinder, so that the ink in the concave part is directly transferred to the paper. Finally, the printed matter is accumulated or rewound through the paper receiving part.

The main structure of gravure press consists of five parts: paper feeding, ink feeding, printing, drying and paper receiving.

Gravure printing products have the advantages of thick ink layer, rich layers, strong stereoscopic impression and good printing quality, and are mainly used for printing exquisite color pictures, trademarks, decorations, securities, color newspapers and so on. Gravure printing machine has not been widely used in China because of its complicated plate-making process, long cycle and environmental pollution caused by benzene-containing ink. Therefore, measures such as improving plate-making process, shortening plate-making time, using pollution-free ink, reducing energy consumption and reducing cost are being studied and improved. The main feature of gravure printing machine is that the graphic part on the printing plate is concave and the blank part is convex, which is just the opposite of the layout structure of relief printing machine. When printing monochrome, the machine first immerses the printing plate into the ink tank and rolls it, so that the whole surface of the printing plate is covered with an ink layer. Then the ink layer belonging to the blank part of the printing plate surface is scraped off, and the convex part forms a blank, while the concave part is filled with ink. The deeper the depression, the thicker the ink layer. The machine transfers the ink in the concave part to the printed matter by pressure, thus obtaining the printed matter. When printing multi-colors, the overprint method or indirect local inking method is used to make the inks of various colors distributed on the relevant parts of the printing plate surface as required. The basic printing principle of printing multicolor is the same as that of printing monochrome. There are two types of printing plates used in gravure printing machines. One is intaglio, that is, negative printing plate; The other is carving. The engraving of engraving plate includes manual engraving, mechanical engraving and electronic engraving.

relief printing machine

A machine in which the graphic information on a printing plate is higher than the blank area.

The ink supply device of the printing machine first distributes the ink evenly, and then transfers the ink to the printing plate through the ink roller. The graphic part of the relief is much higher than the non-graphic part, so the ink can only be transferred to the graphic part of the printing plate, and the non-graphic part has no ink.

Printing characteristics: the ink color is relatively thick (the thickness of the ink layer is about 7μm). Can be printed on a rough substrate. Tone reproducibility is average.