Analysis of Common Frequently Asked Questions about Offset Printing of Computer Bills

The computerized paper is made of web paper and is printed by drilling, tangling, folding, printing, matching, and numbering. At present, there are two types of computer ticket processing methods: on-line processing and step-by-step processing. The processing machines used are one-piece machines that are punched, folded, and printed at the same time, and they are made up of making machines, printing machines, and pagers. Step-by-step processing equipment. Computer tickets mainly include folded computer tickets and small-volume computer tickets. Now that computer paper is mainly used for offset printing, this article is to discuss some common problems in the offset printing of computerized paper.

First, the paper processing

Computer paper paper has a very sensitive water absorption and dehydration, paper moisture content changes will cause paper stretching, compression deformation, and generate static electricity. In the printing process of computer vouchers, the change in the moisture content of the paper is the main cause of the change in paper tension, inaccurate multicolor printing, and paper breakage. Therefore, the note paper should be adjusted before printing so that the moisture content of the paper can be balanced with the relative humidity of the environment, so that the sensitivity of the paper to the ambient temperature, humidity, and the layout moisture can be reduced, and the paper can reduce the telescopic deformation of the paper in the printing process of the note. .

Humidity treatment method: First, the temperature and humidity of the workshop should be controlled and kept constant. The air-conditioning control and humidifier can be used to control the indoor temperature and humidity. To maintain the constant temperature and humidity within the allowable tolerance range, the doors and windows should be closed to prevent direct indoor and outdoor air convection. Before printing, the outer packaging of the web is removed and placed in a printing shop or a paper room. When making folded computer paper, semi-finished products can be printed in the shop for a period of time before printing.

Under the circumstance of little climate change, if the regionality of the paper mill and the printing factory is closer, the humidity time of the purchased web does not need to be too long or the humidity is not adjusted; but when the paper mill and the printing plant are located When the difference is large, or when the paper is purchased during the season where the temperature and humidity change is relatively large, or the production date of the purchased paper is different from the seasonality of the printing date, the humidity adjustment processing is also required.

Second, ink compatibility deployment

Computer paper graphics are generally composed of lines, text, and real-ground patterns. The drum structure uses two plate cylinders to work together on a blanket cylinder for text transmission. The blanket cylinder transfers the ink to the paper through the impression cylinder. This structure can make the two-color overprinting accurate, before and after the two-color printing ink at the same time imprinting, as long as the control of a good ink balance, two-color ink printing graphics can maintain their hue, brightness, saturation. Before and after the ink adaptability has little effect on the printing effect, generally only need to change the ink fluidity and permeability, adjust the ink layer thickness to adjust the printing superimposition effect. Due to the computer ticket paper in the production process is easy to produce paper powder, paper hair, ticket surface text printing and non dot printing, so adjust the ink when appropriate can add some No. 6 varnish to reduce ink viscosity, enhance ink flow It can reduce the stickiness of printing paper and paper powder, improve the effect of printing and ink transfer, and evenly ink, so that the ink can be quickly leveled and the printed image is full, solid, and legible. However, it should be noted that the amount of No. 6 varnish is generally not more than 15% of the amount of ink used, otherwise the amount of ink is too large to split well, and it is easy to get dirty.

Third, the amount of ink regulation and dampening fluid consumption

In the printing of computer tickets, the face line and the text are small in ink consumption. When the ink is adjusted, the ink level is generally controlled by adjusting the ink fountain roller rotation angle to control the amount of ink transferred. The bill surface monitor chapter, solid blocks and other patterns to eat a little more ink, ink fountain roller angle can be slightly adjusted slightly, the output ink layer can be slightly thicker adjustment, adjustment should be based on layout and location of the layout of the map to determine the output Ink volume. When adjusting the ink layer on the surface of the ink fountain roller, the ink supply position of the ink fountain roller and the ink ink layer thickness should be reasonably adjusted to ensure the ink transfer rate.

In addition, the amount of printing ink for bills is also related to the physical properties of the paper, the temperature of the shop, the nature of the ink, the condition of the grits on the plate, the speed of the machine, and so on. It is also necessary to comprehensively consider the above conditions during the adjustment.

The amount of printing fountain solution is subject to various conditions, mainly including the type of ink, the viscosity and fluidity of the ink, the amount of ink contained in the printing plate, the type and structure of the printing plate, the layout and distribution of the printing plate, and the paper. The nature and area, machine speed, etc.

Fourth, roller pressure regulation

The balance between the pressure of the water roller and the ink roller is reasonable, which is the key to realizing ink-water balance, ensuring the correct transfer of pictures and pictures, and ensuring and improving the quality of offset printing products. The principles and methods of adjusting the roll pressure of the computerized offset printing press are the same as those of other offset printing presses. The ink roller and the water roll should be straight when adjusted, and the pressure should be uniform and reasonable. If improperly adjusted, some process problems are easy to occur. For example, when the pressure between the ink rollers of the ink system is uneven or smaller, the ink roller surface will accumulate thicker ink layers due to the ink sliding, especially in the face of the printing ticket. For small bills, such failures are more likely to occur when the ink supply amount or the amount of water supply is large, and in severe cases, ink may accumulate on the printing plate and the blanket. Since computerized offset printers use two plate cylinders to co-imprint one blanket cylinder to transfer ink, the ink deposited on the blanket is transferred to another plate cylinder and transferred to another group. The ink system affects the color saturation (purity) of another color ink.

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