How to improve the printing quality 1

2022-09-22
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How to improve the printing quality

printing is the process of transferring the original image and text to the PS plate, which connects plate making and printing. In the whole printing quality management, environment section is very important. How to improve the quality of printing, reduce waste and reduce costs, according to their own practice, from the following aspects to talk about experience

first, have a high degree of dedication and professionalism

1 The printer operator should master the performance and technical parameters of the printer, cherish the equipment, and maintain the equipment frequently to ensure the normal operation of the printer

2. Keep the environment clean, maintain the indoor temperature and humidity, carefully check the original before printing, analyze and deal with the parts that do not meet the printing requirements according to the specific situation, avoid unnecessary waste, and wipe the two sides of the glass of the printing machine

3. Check whether the specification and size of the original meet the requirements of the operation ticket by referring to the process sheet; Whether the mouth, band mark, color mark and platform mark are complete

II. Quality of the original version

1 First, check the density of the original. The field density of the normal original is about 3.0. At this time, the density of dots, words, lines, etc. meets the requirements of printing. As long as normal exposure and development are carried out. However, in actual production, we often encounter that the density of some originals is low or high, so we need to deal with them according to different situations

a. during the exposure process, due to the low density of the original with low image and text density, light is easy to pass through the edge of the point, so that the light decomposition of the photosensitive layer should not be seen. After development, the point becomes gray and smaller, and the text and lines will become lighter accordingly. On the machine, the ink color is not saturated, which reduces the printing resistance and fails to achieve the desired effect. For this type of original, we should adopt the method of less exposure and less development

b. for the original with high image and text density (the density of the blank part is greater than 0.05), there is a layer of fog on the surface of the original, and there is also a layer of fog when the edges of the corresponding points and lines are not smooth. In China, this layer of gray hinders the passage of light when printing, so that the light decomposition of the photosensitive layer in the gray area at the edge of the points is not complete. After developing, the dot is enlarged, especially the dark tone part of the image is enlarged. When printing, the dark tone is merged and pasted, which also fails to achieve the desired effect. For this kind of original, we should adopt the method of multi exposure and multi development

2. Because of the revision of some pictures and texts, there are more "skylight opening" parts in the original version, which brings certain difficulties to the printing operation. The edge of the tape is too close to the image, which is easy to make the image pad virtual. Because the overlap of the film base will cause static electricity, the middle interlayer is easy to absorb some dust, small sand particles, etc., which will also make the image pad virtual. There are also some original image parts that fold out of the horseshoe nest. After exposure, this part also has the image virtual phenomenon. In view of the above phenomena, the printing operator is required to find and solve them in time

3. In order to save materials, the original edition of some books and periodicals usually uses sulfuric acid paper instead of the printed film, which is used as the original edition after manual composition according to the requirements of plate making. We must pay attention to this kind of original edition: whether the drug film of the text is reflected; Whether the density meets the requirements; Whether the paper is curled and deformed

III. control of plate printing signal strip the plate printing operator shall conduct a matching test of exposure and development before working every day to determine the exposure time, development time and developer concentration suitable for printing and proofing. Methods: first, ensure that the temperature and concentration of the developer meet the development requirements. Then take a small PS plate and put the print signal bar on it for exposure test. Before the test, we should consider the different service objects of printing, and the exposure time test should also be adjusted to varying degrees

a. proofing version: after the signal bar is exposed and developed, the 4-level gray scale requires half a grade to be exposed, 2% of the dots are exposed, 50% of the dots are restored basically accurately, 80% of the dots cannot be reduced by children%, and the edges of the dots are clear and tidy

b. printing plate: after the signal bar is exposed and developed, the level 4 gray scale is required to be polished off by 1.5, 2% of the upper point is required to be polished off, 50% and 80% of the points sharing weal and woe are basically restored accurately, and the point edges are also required to be clear and tidy. The reason why the drying of printing plates and proofing plates are inconsistent is mainly to solve the difference in mechanical performance between proofing machines and printing machines, so as to ensure that the printing and proofing samples basically achieve the same effect in terms of tone, hue and saturation

IV. understand the performance indicators of the PS version, and use the PS version correctly. When replacing the new PS version or using the PS version produced by the same manufacturer with different batch numbers, the photosensitive speed will be different due to different proportion of photosensitive solution, so the exposure time, development time and concentration of developing solution should be changed accordingly. When using the developer, in order to achieve the ideal effect of developing theater, it is best to use the developer matching with the PS version, because the alkali resistance of the PS version produced by different manufacturers is strong or weak. If the PS version with weak alkali resistance is developed with the strong alkaline developer, the photosensitive layer without photodegradation will be seriously affected, and the dot will become smaller and the image tone will be lost after development. When the developer concentration is too high, it will not only corrode the photosensitive layer, but also destroy the oxide film of the printing plate, which will affect the lipophilic property of the printing plate and reduce the printing resistance of the PS plate. If PS plates with strong alkaline resistance are developed with weak alkaline developer, the development will be incomplete. When printing, the printing plate is dirty, which is dominated by the foreign market. Due to the long development time, the aluminum plate base will also be corroded to a certain extent, affecting the use effect of PS plates

v. remove dirt, wipe glue, dry the PS version after development. Before removing dirt, it is necessary to dry the PS version first, because most of the dirt removal parts are close to the image or text, and the revision paste will dissolve with the water on the surface of the base and spread around as soon as it comes into contact with the PS version, which is very easy to erode the image or text, making the edge of the image empty, the lines of the text shallow or the pen broken. When removing dirt, dip the tip of a brush into a small amount of revision paste, gently wipe the dirty areas that need to be repaired and completely remove them in the shortest time, and then rinse them immediately with water to avoid the revision paste drying up on the surface of the PS plate due to the long revision time. In addition, too long revision time is also easy to make the layout dirty. After the cleaning, wipe a layer of protective glue on the PS plate in time. If the glue is not wiped in time, the hydrophilic part of the PS plate will be oxidized, and the hydrophilic property will be reduced. The PS plate will be dirty during printing. Correct glue wiping method: gently wipe a thin layer on the layout with a sand cloth dipped in an appropriate amount of glue, and apply it evenly, so that all hydrophilic layers are protected. After wiping the glue, blow dry the PS version, and then protect it

protection method: read the functional features and operating procedures of the drop hammer impact tester shared by our company for you between every two PS versions, separated by a neutral moisture-proof paper, and the storage temperature is 25. C, and the relative humidity is about 60%

if the printing quality is in a stable state for a long time, the printing staff must have the spirit of love and dedication, constantly accumulate experience in work, and find a set of scientific standardized data suitable for printing and proofing, so that they can be handy at work, meet the current needs of large-scale printing plate drying, improve work efficiency and ensure product quality

2. Overprint clear water (commonly known as water pressure). In the case that the printing paper is not easy to master, in order to prevent the paper from stretching in the printing, you can first overprint the square of clear water to make the paper meet the printing requirements, and then start printing the color. This method has a certain effect on solving the inaccurate overprint

3. Control the moisture content of the printing plate. Moisture in the printing plate. The moisture content of the printing page is the key factor to control the paper expansion and contraction. The moisture content of the page is transmitted to the paper through leather cloth. The greater the moisture content of the page, the greater the expansion and contraction. Therefore, the moisture content of the layout should be controlled as small as possible, especially when printing 80g double offset paper

4. Use the plate drawing machine to stretch the printing plate. Generally, the monochrome machine is in the third and fourth color printing process, and the two-color machine is in the second printing process. The image on the paper is stretched and enlarged, resulting in inaccurate overprint. This is because PS plates have good ductility, which can be stretched by a plate drawing machine, so that the printing plate image can be stretched evenly with the image on the paper to make the overprint accurate

at present, most small and medium-sized printing and repairing enterprises in China generally do not have air conditioning equipment. Most of the practice is to sprinkle some water around the machine to increase the air humidity. For products with low requirements for non dot printing, spray water directly towards the paper edge with a spray barrel and then print on the machine; When the air humidity in the workshop is high, it is best to cover the cut paper with a plastic cover to prevent it from becoming longer due to moisture; If it is secondary printing, the method of borrowing plate lines can be used to compensate for the flexibility of the image. In general, there are many methods to solve the inaccurate overprint caused by paper expansion. As long as we strengthen the discussion and management of printing process, it can generally be solved

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