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In addition, due to the fact that there are certain differences in the hue of the commonly used ink, there is also a certain degree of difference in the whiteness of the printed substrate. Therefore, it is necessary to use a color management system to correct it. The basis for these data revisions is the test-testing done by professional flexo platemaking companies to various flexographic printing plants. The plate-making company enters the data it obtained in the beta test into the computer and calculates the compensation in the computer. Based on these compensated data, no Romlin numbers can be made. In accordance with the above procedures, printed samples will be closer to the printing effect; otherwise, good results will not be obtained. Professional flexographic plate-making companies generally pay great attention to this method, which is called "fingerprint" control. Just like everyone's fingerprints are different, the printing status of each printing press is not the same for every flexo printer. This "fingerprint" control is used for compensation curves. In actual production, we do feel that this is a very effective method.
Second, the proofing after the plate making After the user can make a reservation, the plate making company releases the soft film printing plate, after the inspection sends the printing factory.
After receiving the printing plate, the printing factory still needs to check the printing plate thoroughly, especially to check if there are any extra lines and the size is correct (because Cromartin's proofing cannot be 1:1, it always scales down, so When the film size is often out of the question), there is no dust stains when printing, especially something like fiber, there must be large and small pits on the flexo version; sometimes when washing version If you do not deal with the layout, you will leave some raised unwanted material on the plate. These are all carefully checked by the printing house before the sticker.
After the operator of the plate press receives an unmistakable printing plate, he or she must carefully paste it with the help of a special optical reflector on the plate or a monitoring screen with a magnification of nearly 20 times. This is a relatively simple process that requires careful operation. After affixing the printing plate roller (or the sleeve installed on the air-bearing roller), do not draw a sample. There are currently two different approaches in the domestic flexo printing industry: One approach is not proofing, straightforward on the machine overprint, if there is a problem on the layout or the sticker is not allowed, then remove it and do it again. Another approach is to post proofing the proofing of the special proofing machine. After proofing, the proofs will be proofed one by one on copper-copper paper to obtain a printed sample on the copperplate paper. Edition accuracy and layout. If it is qualified, the printing effect is basically still possible; if it is required to re-post, if the double-sided tape has not yet been pressed, tearing off and re-attaching will not waste material, and the normal production of the printing press will be synchronized with the proofing of the loading plate. It also does not waste production hours.
According to the author's knowledge, most of the current domestic unit type flexographic presses do not proof after the printing plate is attached. The prototype of the satellite flexographic printing press has been used for proofing. The basic starting point is to save auxiliary materials such as double-sided adhesives and not to waste man-hours for printing presses. The author mediates the latter based on his years of experience.
Commonly used special proofing proofing machine is the product of Italy BIEFFEBI Company. The width of the impression roller is 135CM and 180CM. It is designed and manufactured for wide-format satellite type flexo printing machine. The circumference of the embossing cylinder is 106CM, the maximum circumference of the corresponding printing plate cylinder is 100CM, the minimum is 24CM, these data are more than enough for the 6-8 color satellite flexographic printing machine. The specific operation is to first apply a 60-80 g/m2 coated paper on the surface of the embossing cylinder (the paper surface cannot be too rough), and then use a hand-held rubber inking roller to apply ink. The ink may be oily, such as offset printing ink, but other inks may also be used, but care must be taken not to use quick-drying inks. Otherwise, drying on one side of the ink will cause the ink to roll in some places after the printing roller is turned around. In some places, ink cannot be found at all.
After the one-color ink is finished, remove the plate roller, and then change the plate roller version of another color group. According to the cross line mark printed on the copper plate paper, the cross line should be aligned. Errors, after the paste on the second color ink, repeat the previous steps, color paste, color proofing. Finally, a copy of a flexo-like product on a copperplate paper was obtained. The disadvantage of this method is that the proofing speed is slow. It is necessary to manually apply the ink. After each sample is finished, it is also cleaned and blown dry with compressed air. However, from the point of view of taking a certain amount of production man-hours in wide-format sanitary flexo printing machines, it is still worthwhile to ensure that each set of printing plates is qualified and repetitive hanging plates are avoided. of. Of course, this is only one of the words, to be verified by the friends of the domestic flexo printing industry.
In summary, in the flexographic printing process, as with offset printing and gravure printing, the pre-print proofing process is very important and indispensable. Even if the platemaking process is developed to digital plateless direct plate making, the proofing technology is still very necessary, and even more essential, it may be at the stage of no plate printing, proofing is no longer needed, but when there is no plate printing, How much difference between proofing and printing?
Flexographic Printing Prepress (2)
In the proofing before platemaking, there is a very important data curve, which is the high-speed curve of the tone. Since flexographic printing has the most powerful dot gains in the middle, and the high-profile areas can't completely make up 1% of the small dots, the level of low-key flexo printing and high school education and their percentage of outlets are not all ideal linear relationships. Adjusting the varicosity will often be a curve with a large curvature. For example, the flexographic printing dot enlargement rate of the author's unit is about 15%. Therefore, the mid-tone portion of the layered curve is curved more severely. In the actual plate making, this condition must be taken into account and compensated to give a reversed curve. Combine it with the level curve to approximate a straight line.