Analysis on the control of the most popular proces

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Analysis of the control of various processes and printing technologies

small cartons and carton products often have various structural layouts coexisting. For example, there are not only the layout based on field printing, but also the printing layout with lines, words, lines and field patterns coexisting; There are not only gold and silver pages that cannot be displayed by spectral colors, but also pages with spot colors and four primary colors. If offset printing and embossing (or gravure printing) processes are used to print products in different ways, the printing products have their own advantageous process characteristics. The combination of multiple processes to print cartons, cartons and other packaged products can improve the internal quality of products. Offset printing process has good reproduction effect, soft tone, clear dots, rich printing layers, and it is not easy to stick dirty products in a large area of printing. The embossing and gravure printing process has the advantages of thick and full ink layer, bright color and high gloss. Therefore, using the advantages of different printing processes in recent years to print products with lines, characters, lines and field patterns, as well as layouts of various colors, integrating the advantages of different printing methods, and printing the same product with process synthesis can not only give full play to the utilization of equipment, but also synchronously improve product quality and economic benefits

reasonable arrangement of various combined printing processes

offset printing process has light printing pressure, relatively small printing deformation value, and the product is not easy to be sticky and dirty, so it is suitable for printing chromatic plates, lines, small words, negative images and large-area field layouts

the embossing process can achieve a large amount of ink supply at one time, which is more suitable for printing gold and silver ink layout, field, line or text layout. In terms of printing characteristics, the ink layer of offset printing process is thin, the ink is easy to dry, and the product does not produce convex marks, which does not affect the normal overprint of embossing. However, the slow drying of the ink in the embossing process will have some adverse effects on the normal chromaticity. Therefore, the overprint sequence of the products with the combination of offset and embossment should generally be: offset printing first, embossing printing second; Small pages are printed first, and large pages are printed later; The ink with strong hiding power is printed first, and the ink with strong transparency is printed later. For example, black words or patterns are overprinted on the red and yellow (with the exception of white ink flushing at present). The black page can be printed first, and other colors can be printed later. In this way, because the overprint color has strong transparency, black can still show a pure black color

technical control essentials of combining various processes with printing

1. Do a good job in the process and technical control of prepress design

the embossing field layout should avoid the small negative lines and words in the same color plate, so as to avoid that due to pressure and ink supply, it is easy to produce paste and uneven pressure, which will affect the printing quality of products [encyclopedia Weibo]. The overprint part of the embossed layout should be as far as possible to leave a certain gap around the edge of the overprint layout or appropriately expand the edge of the light color layout (so that the edge of the overprint layout can be overlapped and covered), so that the slight overprint is not accurate and is not easy to be detected by the naked eye

2. Do a good job in the technical control of the mosaic process

the overprint parts of the layout should be spliced close to the bite and the pull gauge (side gauge) as far as possible to avoid inaccurate overprint due to the expansion and contraction of the paper. In addition, it is not suitable to use two processes to overprint the layout with large or multi block chromatic layout across the river (core)

3. Pay attention to the reasonable selection of offset printing plate

ps plate has a thin plate. After it is installed on the surface of the drum, its wrapping angle is relatively small, and the elongation of the printing plate is also small, and it can maintain close contact with the drum, which is conducive to improving the overprint accuracy of embossed products. Therefore, PS plate should be selected for offset printing process

4. Pay attention to the process and technical control of the bottom support of the printing plate

small size packaging products are often printed by relief printing machines with four open or split circle flattening structure. The characteristics of the bottom support material of the printing plate have a great impact on the printing pressure, overprint accuracy and ink quality effect. The traditional wooden bottom support is not solid, with poor squareness, flatness and stability. It is prone to bow and deformation, and the printing quality is difficult to guarantee. Therefore, relief printing should adopt solid, flat, square and stable aluminum or cast iron magnetic plate table, rubber and plastic products quality inspection equipment, its own technology, experimental methods, inspection rules and requirements of marks, labels, instructions, packaging, storage, transportation and other gold attribute materials, which is the basis of improving product registration and ink quality

5. Pay attention to the pressure control technology of printing [encyclopedia Weibo]

the printing pressure should be adjusted evenly and moderately. Excessive pressure is easy to stretch and deform the printing sheet compared with the high gloss surface effect of flame retardant ABS and hips, resulting in inaccurate overprinting. Therefore, the printing pressure of the embossing process must not be too large, but the printing pressure should be as light as possible, and the ideal printing should be carried out on the premise of meeting the uniform and full ink color of the layout

6. Pay attention to the technical control of the lining process

the lining is the medium to realize the transfer of pressure and imprint. Its characteristics also affect the registration and ink quality of the product. Therefore, the deformation coefficient of the lining material should be as small as possible, and the material should be neutral and hard. At the same time, the thickness of the lining must be determined in strict accordance with the technical parameters of the equipment specifications. In addition, the lining must be tightly wrapped and tight, and there must be no virtual looseness or bulging. Do not repeatedly patch or excavate on the embossed lining to prevent inaccurate overprint and ghosting

7. Pay attention to the technical control of ink balance.

to control the ink balance in offset printing process is to print with a minimum supply of fountain solution under the condition of maintaining ink balance. The abnormal balance method of large ink and large water should be avoided to prevent deformation due to excessive water absorption on the paper

8. Pay attention to controlling the temperature and humidity of the printing environment

controlling the temperature and humidity of the printing workshop is an important part of improving the overprint accuracy of products. The temperature and humidity of offset and embossing workshops should be kept in a relative balance, and there should be no large gap between high and low, otherwise, it is easy to cause inaccurate overprint. In general, most small and medium-sized printing enterprises cannot effectively and accurately control the temperature and humidity of the production site due to the limitations of conditions. They often control through simple methods such as opening and closing doors and windows or splashing water on the ground based on experience, which can also play a certain role

9. Pay attention to the technical control before the paperboard is put into use

the paperboard is very sensitive to the temperature and humidity changes of the external environment, especially the white paperboard just produced, which is most prone to expansion and variation due to the changes of temperature and humidity, resulting in inaccurate overprint of the product. In order to reduce the chance of this situation, for the newly produced white paperboard, after the printing factory transports it back, it generally needs to be stored for a period of time, so that the characteristics of the paperboard are relatively stable, and it is not easy to overprint when it is put into use. In addition, the cut paperboard should be sent to the printing workshop immediately to make it balance with the temperature and humidity of the printing workshop before printing, which is conducive to improving the registration accuracy of products

10. Pay attention to the technical level of paper cutting process

how accurate the specification of paperboard is will also affect the overprint of products. Because of different machine structures, their front gauge and pull gauge positions are not the same. In this way, if the edge of the paperboard is not cut squarely enough, and there are beveled edges or wavy edges, it will cause inaccurate overprint. This requires that the edges of the paperboard of the products with glue convex combination must be cut into right angles and straight lines, and there must be no beveled edges or wavy edges. In order to improve the cutting accuracy of paperboard, we must strictly control the cutting thickness, because the thicker the paper stack, the softer the paper, the more severe the paper surface deformation when the paper presser is pressed down. Therefore, the less the cutting thickness of each stack of paperboard, the more conducive to improving the cutting accuracy of paperboard. In addition, the blade edge should also be kept sharp, and the appropriate blade angle should be selected according to the hardness of the paper, which is also an important measure to improve the cutting accuracy

11. Pay attention to the production cycle of product overprint

when the previous color or several colors of the printed matter are printed [encyclopedia Weibo], those who can overprint should be overprinted immediately, so as to avoid stretching and variation of the printed matter due to too long delay, resulting in inaccurate overprint

12. Pay attention to the protection of semi-finished products after printing

the semi-finished products after printing should be sealed with plastic film to prevent the cardboard from absorbing moisture from the outside air or losing moisture, so as to avoid or reduce the adverse phenomenon of expansion and variation of semi-finished products

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