Pre-press, printing and post-press are the three major processes of modern printing process. Each process directly affects the normal operation of the following processes. Any printed product can not be separated from the cooperation of each process, scientific and reasonable pre-process design, It has a multiplier effect on the process of the later process, and plays an important role in ensuring product quality and improving production efficiency. 1. The rational design of the prepress process is conducive to the production of printing ①Add a black version, which can effectively solve the effect of the lack of density of the three primary color printing and the color reproduction error on color reproduction, correct the color cast, and carry the text lines directly with a black version to avoid the problem of multi-color overprinting of text printing . ② UCR (Underground Color Removal) process plays a significant role in improving the dot reproduction clarity, controlling paste, and accelerating the drying of printed sheets. It effectively avoids the series of problems caused by large amounts of ink printing in dark areas, saving costs and improving efficiency. Adapt to high-speed printing. In actual production, the total area of ​​four-color overprinted dots is usually in the range of 250% to 270%. When the background color is removed, it is generally possible to remove a total of about 50% to 80% of the dots, and only need to increase by about 15%. The 20% black version can replace the overprinting effect of about 50% to 80% of the Y, M, and C primary colors. After calculation, increasing the background color removal by 50% can reduce the ink cost by 10% to 15%. In the actual use of background color removal, it is necessary to take into account both the amount of background color removal and the range of background color removal. The simple and practical removal amount formula is as follows: ③In theory, the GCR (gray component substitution) process can replace the equal parts of the three primary colors with black ink. In actual application, when black ink is used to replace the minimum amount of primary color containing gray color, the basic color of the color will also be weakened, resulting in insufficient saturation of the dark primary color, or even color cast. This is because the hue, lightness, and saturation of inks, etc., have not yet reached the ideal requirements. The UCR process replaces all neutral gray components with black. Practice has proved that it will cause the reduction of the vividness of the color, so the black version must be appropriately lightened and adjusted. In practice, it is best to use UCR process, GCR process is not yet mature. ⑤When printing single-sheet printing (taking 16-sheet printing as an example), it is necessary to put pages with rich graphics and large ink consumption on the side of the bite, which can not only ensure accurate color, but also Avoid the phenomenon that the amount of ink in the trailing part is large and the printed sheet is curled down and the trailing edge is scratched. This is because of the four inking rollers, the two near the bite edge are the main inking units, while the other two only serve to distribute and collect ink, arranging pages with rich graphics and text in the bite. It can effectively ensure sufficient ink supply for pages with large ink consumption and fast and accurate color follow-up. ⑥ Books or albums with cross-layout layouts, in order to accurately match the color, try to arrange the cross-drawing components on the same layout or the same printed sheet. If they are distributed on different layouts or different printed sheets, not only may occur after binding Color difference will also cause inaccurate cross-picture connection and affect the binding quality. ⑦If a large area of ​​black field is needed in color printing, in fact, we can completely use another process design method to meet its visual effect requirements on black field, and it will not cause too much trouble to the printing production. That is 100% black + 30% ~ 60% cyan or 100% black + 10% ~ 30% light blue. Such black printing is more shiny than single black, and at the same time, because of the existence of the green plate, it can make up for the defects of black plate printing. Of course, it can also be adjusted according to the actual situation. For large-format prints, you can even use 100% black + 70% cyan (or 30% light blue). This is because the printing area is too large and the printing speed is fast. The ink color is solid, so the value increases accordingly. [next] 2. The rational design of the pre-press process can greatly facilitate the production of the post-press process Whether post-press processing is efficient and smooth depends largely on whether the pre-press process is properly designed. Many pre-press workers do not attach importance to the learning of post-press processing related knowledge, and the knowledge structure is incomplete. In fact, properly designed can reduce costs and improve efficiency; on the contrary, it takes time and effort, with less effort, and serious cases can also cause quality accidents. Therefore, scientific and reasonable pre-press process design is very important. ①For the common bookbinding forms such as saddle stitching, flat binding, and perfect binding, due to the use of two different ways of collating and overlapping, there are two cases for the processing of non-integrated scraps: For saddle stitching ( For nesting), the heading should be placed after the first post or before the tailing; for flat binding and perfect binding (overlaying), the heading should be placed after the first post and before the tailing. Otherwise, if the scrapbook is placed in the first or last post of a book, due to the loss of the squeezing and protection of other signatures, the parts of the exposed scrapbook are very easy to fall off or even be damaged by crushing, which greatly affects Productivity. Reasonable design arrangement not only facilitates the matching of posts, but also ensures the quality of the book. The book is strong and not easy to loosen. ② For the bookbinding products with full-page printing varnish (such as matt varnish, UV varnish, etc.), the presence of varnish blocks the adhesion effect of glue on each signature, so the finished product is bound. It is very easy to produce quality accidents such as separation of signatures and separation of covers and book blocks. When designing the process of such products, leave 1.5mm away from the connecting parts of books and periodicals without varnishing, to ensure that the adhesive glue penetrates and sticks to each book. In the same way, 4-5mm white glue should be left on the front page of cover 2 and the front page of cover text, the third page and the last page of the cover text to ensure that the cover and book block are firmly adhered. The modern binding process gradually adopts special glue suitable for various varnishes, and the binding quality has improved significantly. ③When making the die-cut version of the packaging box, when there are multiple boxes in a layout, the minimum distance between the finished lines of adjacent boxes should be more than 3mm. This is because when making a die-cutting plate, the minimum distance between adjacent saw marks must be more than 3mm in order to embed the knife line smoothly. Irregular box-shaped edges, try not to have angled corners with very small angles. In this way, when making a die-cut version, multiple sections of buried knife are needed, and there are too many interfaces, which causes burrs on the edges of the product. It should be designed into a circular arc with a larger angle, which is conducive to the overall embedding of the knife. Try to use the composition method for typesetting to improve paper utilization. After completing the imposition, it is best to produce a 1: 1 typesetting film to facilitate the printing plant's sawing. For products that are produced in multiple batches on a regular basis, each typesetting before printing should strictly refer to the previously made die-cut plate, so that the die-cut plate can be reused, saving time and effort. ④ Make small tags, stickers and other things that need to be die-cut and punched, pay attention, and try not to design the outer border. This is because if there is a slight deviation in positioning during die cutting, a large side and a small side will appear, which is particularly obvious. [next] 3. Pay attention to the details of the printing process to avoid unnecessary losses and bring great convenience to the post-printing process ①When printing the packaging box, in addition to paying attention to color, registration, etc., you must pay special attention to the position of the graphic on the layout. For example, the sticky position of the packaging box, the flap, and the bottom of the pocket are often blank without bleeding. Zhong should carefully draw the box sample on the layout to ensure that the components of the packaging box have enough space on the layout. Otherwise, insufficient position will occur during die cutting, resulting in quality accidents and economic losses. In the case of extremely tight layout, you can borrow the bite position (about 1cm), trailing edge, and side edge of the printed sheet as the sticking position or flap of the packaging box. ②When printing large-area solid prints, it is difficult to maintain uniform ink color. There are very high requirements for ink path adjustment and printing pressure adjustment, which is not easy to do. A good practice is to print with a small amount of ink for the first pass and increase the amount of ink for the second pass, and then print the printed sheet (the bite becomes trailing), so that the left and right ink amounts of the printed sheet are balanced. Avoiding the requirement for high-precision adjustment of the ink path and printing pressure, especially for production conditions where the machine condition is not very good, is a very effective means. For this kind of large-volume field printing, stack as many yards as possible to reduce the amount of powder sprayed, which has many benefits for later stamping and laminating. ③ For the reverse printing method of the heel bucket (turning back and forth, the bite becomes trailing), since two bite edges are used, in order to achieve accurate overprinting on the front and back sides, the long edge (bite and trailing edge) must be required when cutting white paper Edge) must be strictly trimmed. In order to ensure the same paper size on the machine, it is best to use a program-controlled paper cutter, which controls the cutting error ≤0.1mm, which is convenient for post-process cutting, folding, and binding. Because the heel bucket occupies two bite edges, the effective layout becomes smaller. For the convenience of typesetting, the front and rear positions of the front gauge are reasonably adjusted to minimize the width of the platen of the impression cylinder and the utilization rate of the layout. ④ For self-reprinting (left and right, the bite is unchanged), especially the inner pages of books and periodicals, two pull rules must be used alternately to ensure accurate front and back overprinting. Some operators are greedy for convenience, and still use the same pull gauge when printing on the reverse side, which does not meet the operation requirements. The above is just a little experience accumulated in daily work, which is not exhaustive. In actual production, the scientific and reasonable process design of the previous process is not only the basic premise for improving the production efficiency of the latter process, but also an important guarantee for product quality. There are still many work experiences similar to those described in this article, and I will not repeat them one by one here. Experts are welcome to add analysis, criticism and correction. Round Dining Table,Dining Table 6 Seater,Dining Table 4 Seater,Corner Dining Table CAMOSA HOME , https://www.camosa-funiture.com
R = removal density / replication density range × 100% = DR / Dr × 100%
Among them: DR-removal density, Dr-replication density range.
The removal range is generally used for the neutral gray area of ​​the dark tone part of the screen, that is to say, the area with a significant background color removal effect should be located in the part of the original close to the neutral gray. For saturated or solid color areas, background color removal should be used sparingly or not as much as possible. This will ensure the clarity and vividness of the original screen. As the amount of black plates increases, the original colors will appear dark and dull. While determining the amount of background color removal, it is also necessary to select a suitable starting point for the removal of the background color. In production, it is generally appropriate to fix the starting point of the black version at about 50%. For the dark primary colors that may appear because of the large amount of gray components, the background color removal process is used and the saturation is not enough, which can be corrected in Photoshop.