Principle and Application of Gravure Printing

In gravure printing, the entire surface of the printing plate is covered with ink, and then a special scraping mechanism is used to remove the ink from the blank parts so that the ink only remains in the cells of the graphics and text parts, and then under greater pressure , transfer the ink to the surface of the substrate to obtain printed matter. Gravure printing is a direct printing. The picture and text part of the printing plate is concave, and the degree of depression varies with the depth of the image. The blank part of the printing plate is convex and on the same plane.

Gravure printing, referred to as gravure printing, is one of the four major printing methods. Gravure printing is a direct printing method that directly imprints the ink contained in the pits of the gravure onto the substrate. The shades of the printed image are determined by the size and depth of the pits. If the pits are deeper, , then it contains more ink, and the ink layer left on the substrate after embossing will be thicker; on the contrary, if the pits are shallow, it will contain less ink, and the ink layer left on the substrate after embossing will be thicker. Just thinner. The printing plate of gravure printing is composed of pits corresponding to the original images and text and the surface of the printing plate. During printing, ink is filled into the pits, and the ink on the surface of the printing plate is scraped off with a scraper. There is a certain pressure contact between the printing plate and the substrate, and the ink in the pits is transferred to the substrate to complete printing. As a type of printing process, gravure printing has the advantages of thick ink layer, bright colors, high saturation, high printing plate durability, stable printing quality, and fast printing speed in the fields of printing, packaging and graphic publishing. occupy an extremely important position.

Printing Type

The types of gravure printing are divided into two categories according to the plate making method: engraving gravure and etching gravure.

Engraving gravure

Engraving gravure is to use a carving knife to directly carve pits corresponding to the original graphics and text on the surface of the printing plate cylinder. According to the control method of the carving knife, it can be divided into manual engraving intaglio, mechanical engraving intaglio and electronic engraving gravure.

Etched gravure

The etched gravure plate is made by etching ink pits on the surface of the printing plate cylinder using chemical etching according to the original image and text. According to the different methods of converting original images and text, etching gravure can be divided into etching gravure, photogravure, and dot gravure.

Etched gravure plates are made using a platemaking method that combines engraving and etching. That is, the shape of the original image and text is first carved by hand, and then the intaglio is made by etching.

Photogravure is widely used and is the most commonly used printing plate in gravure printing. It is mainly used for printing painting plates, etc.

Dot gravure is mainly used for packaging, decoration printing and building materials printing.

Printing ink

Gravure ink is composed of solid resin, volatile solvents, pigments, fillers and additives. It does not contain vegetable oil, and its drying method is mostly volatile. Gravure ink can be divided into three types: shadow gravure ink; plastic gravure ink; alcohol-soluble gravure ink. The functions of solvents in ink include: dissolving or dispersing all solid components in the ink; moistening the surface of the printed substrate; adjusting the drying speed of the ink; adjusting the consistency of the ink to make it suitable for the inking requirements of the printing plate.

Printing material

Gravure printing can be used on a wide range of materials, but it is commonly used to print high-end paper and plastic films.

Printing machinery

A gravure printing machine usually consists of eight major parts, including the unwinding part, guide roller, pressure roller, printing roller, inking part, doctor blade, dryer, and winding part. Some gravure printing machines also include a power system and a calibration system. and electrical systems.

Gravure printing process

Due to the high degree of automation of the printing machine and the good plate making quality, the process operation of gravure printing is simpler and easier to master than offset printing. The process flow is as follows:

Pre-press preparation→Publishing→Adjusting rules→Formal printing→Post-press processing

Advantages and Disadvantages

Advantages: Ink expressiveness is about 90%, with rich tones. Color reproduction is strong. The layout is durable. The printing quantity is huge. The range of paper used is wide, and materials other than paper can also be printed.

Disadvantages: The plate making fee is expensive, the printing fee is also expensive, the plate making work is complicated, and it is not suitable for small quantities of prints.

Gravure printing application range

Engraving gravure printing, because of its exquisite lines and difficulty in counterfeiting, is used to print securities, such as banknotes, stocks, gift certificates, stamps, certificates of commercial reputation or stationery, etc. Due to its high cost of plate making and printing, few people use it for general printing. As for gravure, although its plate making process is more complicated and its cost is more expensive, it is not suitable for printing small quantities of prints. It is generally used in large quantities of printed matter, such as color magazines and currently popular building materials printing, etc. All extremely suitable. Because gravure printing uses a high-speed rotary machine, it is not only fast but also the ink film printed is much thicker than that of letterpress printing or offset printing.