Analysis on the Main Points of the Hanging Net Process Printed by Commonly Used Books and Periodicals (I)

With the development of printing technology and the application and development of various new materials and new processes, the original plate-making net production process has not been adapted to the current printing requirements of the books and publications, and we need to make a good study of the technology of printing linked webs. Product quality requirements, the production characteristics of the printing press, the suitability of the printing materials, the proficiency of the printing technology, and other conditions to set the appropriate number of hanging lines, and strive to print a high level of books and products.

1 commonly used books hanging net concept

There are 80, 110, 133, 150, 175, 200 lpi, etc., which are commonly used in the printing process. It is an important technical indicator in the printing process. There is another concept that is the dot size or dot area rate. For example, M80% means that the red dot size accounts for 80% of the dot space. It is also called 80% dot, and 100% refers to the dot size to cover the dot space. The location, which is called “in the field” in printing, is due to the fact that there are no outlets in 0%, and there are only outlets in the outlets. No ink is printed on this place, which is called “blank”.

The number of hanging screens is greatly related to paper, ink, printing machines, etc. If a picture with a high number of hanging screens is printed on an ordinary offset paper, the printing of the picture will not only be reproduced more exquisitely, but will be changed due to the expansion of printing outlets. In order to get a good idea, before printing a film (or CTP plate) before printing, it is necessary to understand the type of printing paper, the type of printing machine, and the production process to determine the accuracy of the hanging net. Poor paper quality, low performance of the printing press, and inferior quality of the ink should be relatively low, and vice versa.

Point of view. At present, most of the products in the books and periodicals use amplitude modulation nets. Therefore, there are net angles. For example, in the case of monochrome printing, the screen angle is often 45 degrees, which is the most visually comfortable and difficult to detect the existence of dots, resulting in the effect of continuous gray tone. As for printing with two or more colors, it is necessary to pay attention to the combination of the angles of the two nets, otherwise it is easy to produce unnecessary patterns. Usually, if the angle between the two screens is different by 30 degrees, collision will not occur. In general two-color printing, the main color or dark color is 45 degrees, and the light color is 75 degrees; three-color printing is 45 degrees, 75 degrees, and 15 degrees, respectively, and the four-color printing is 45 degrees, 90 degrees, and 15 degrees. Black 75 degrees (four colors + spot colors in the spot color, the general plate for the field, there is no network of points). These angles are not static, but should be adjusted accordingly based on actual products and production needs.

2 Quality requirements for books and magazines

1 High-grade and exquisite books and products include color or single-color albums, product brochures, reference books (words, dictionaries), monographs, etc. The printing requirements are strict, the materials are high-grade, and the binding design is exquisite. According to the publications of the State Press and Publication Administration The requirements for batch products should reach a good level. The number of printed screens is about 250 lpi, and even 300 lines of CTP are used.

2 Ordinary books and periodicals products include cultural books, books and magazines, and various types of textbooks and supplementary books. There are certain printing requirements, materials are generally available, and the price is low. The volume products should meet the requirements of qualified (more than 30% of good products). The number of printed screens is 80 to 200 lpi.

3 Production Characteristics of Offset Offset Printing Machine

1 sheetfed offset printing machine

China-made monochrome, double-color and multi-color sheetfed offset presses, due to manufacturing processes, precision and other reasons, the number of printed screens commonly used 175lpi.

Imported high-speed modern high-speed printing presses such as Heidelberg, KBA, Manroland, Komori, and Akiyama have advanced performance, and the number of printed screens is high, generally between 175 and 250 lpi, and a high of about 300 lpi.

Domestic BB type double-sided printing machine, because of the machine design reason, the dot enlargement rate is large, the number of printing hanging lines is less than or equal to 150lpi, the same imported type, the number of printing hanging lines is less than or equal to 200lpi, single-sided lithographic sheetfed printing machine with flip printing The number of hanging lines is ≤ 250 lpi.

2 web offset press

On behalf of the domestic mainstream 787, 880, 890 single, double, four-color and other models, due to manufacturing processes, precision and other reasons, the number of printed screens hanging around 150lpi.

Imported modern high-speed rotary or commercial rotary presses such as Heidelberg, Manroland, Komori, and Mitsubishi have generally higher than 150 lpi and about 225 lpi.

(to be continued)