Technical problems arising from the hottest offset

2022-10-23
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Technical problems arising from offset printing

1 To master the exposure time, development time

offset printing control and master the ratio of exposure time, development time, developer humidity and concentration is one of the ways to reduce point expansion and reduction. The four-color film produced by color separation transfers the image and text points to the printing plate through the process of printing. It is required that the expansion and loss of points should be as few as possible, 3% - 5% points should not be lost, 5% points should not be expanded, 95% - 98% points should not be pasted, points should be solid, point particles should be round and neat, points should be free of white spots, burrs and edges, and the level of gradation should be rich, complete and clear

this requires accurate preparation of PS version developer, according to the formula proportion of the developer instructions, do not be more or less. The exposure time is controlled by gray scale and plate printing signal strip. After the printing plate is exposed, use a 5-10 times magnifying glass to check the loss, paste and dot expansion at the scale and signal strip level

2. Reasonably select offset printing lining materials and adjust the printing pressure

offset printing has three forms of lining: hard, neutral and soft. Which kind of lining is the best? It can be said that each has its own characteristics. Offset printing is an indirect printing method, which requires the elastomer in the middle of the rubber drum to transfer the image and text points of the printing plate to the paper surface. The rubber patch and its lining material are the intermediate media for the image and text transfer in offset printing. Without lining, there is no printing pressure, and without indirect printing, there is no offset printing

through the adjustment of the lining thickness of the offset press, we can get the reasonable and best printing pressure, enhance the uniformity of the ink color of the printing products and the clarity of the dots. In addition, reasonable lining is very beneficial to reduce the dot expansion and improve the printing resistance of the printing plate

the printing pressure is obtained by adjusting the lining thickness and the center distance of the drum. Generally speaking, the low-grade homogeneity will change the inspection data to make them appear to meet the requirements of competition, the "crowding out" of bidding, the constraints of foreign hidden technical barriers and other factors, which make the current domestic testing instruments in a difficult situation. The appropriateness of the printing pressure is often shown through the quality of printed products

the pressure should be based on the premise that the printed matter is a little solid, the graphics and texts are clear, the colors are bright and the shades are appropriate, and the smaller the application is, the better. It is very important to control the expansion and deformation of the points, and adjust the accurate printing pressure. If the printing pressure is large, the points will expand

accurately calculate and measure the thickness of the rubber drum lining with a micrometer in the work, adjust the center distance between the two rollers, and evenly use the minimum printing pressure on the basis that the marking is strong enough within the allowable range of point expansion

3. There are probably several kinds of faults that often occur in offset printing to control the ink balance and reduce the point spread tensile testing machine: large

offset printing can improve the quality of printing products only by mastering and controlling the ink balance. It is advocated to use as little water in the layout as possible on the premise of not dirty version and paste version, so as to compare the emulsification of ink and the expansion and deformation of paper. The ink balance is also a standard to measure the technical level of offset printing operators, Only when the ink balance is achieved, the paper has small telescopic deformation, high overprint accuracy, bright colors, and the hue and hue can be consistent with the printing of a batch of samples. The ink color depth of a batch of prints can be enhanced, and the combination of production, study, and research depth can be achieved. The printed point particles are round and solid, the flat line is flat, and the expansion of points is reduced at the same time

during offset printing, avoid the dot expansion phenomenon of large water and ink, and the ink layer is too thick to spread outward. Control 3% ~ 5% of the small dots in the bright tone area not to be lost, 5% of the intermediate tone points not to be expanded and expanded, and 95% ~ 97% of the large dots in the dark tone area not to be pasted. The control standard of ink volume is: on the premise of strong and clear graphic dots and accurate color phase of the imprinted ink, use as little ink volume as possible

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