Problems and Difficulties in the Process of Fully-open Map Printing

The printing of full-open maps is a special case of sheet-fed offset printing. Its printing process has its inherent characteristics: (1) Fully-open map as a whole, its printing format is relatively large; (2) it-like nothing Continuous network change, but there is a large area of ​​flat screen; (3) Fitting is a key point of full-on map printing; (4) There are more spot colors or specified composite colors (geological maps sometimes as many as a dozen colors) (5) The number of prints for most types of maps is relatively small (more often - two thousand, or as few as one or two hundred); (6) There are many types of printing paper (sometimes the same drawing requires the simultaneous printing of offset paper, coated paper, and silk , Tyvek, etc.); (7) There are many graphic prints (at least two full open, many full L open). Because of the above features, full-open maps are prone to problems that are not common during off-press printing, or that are easier to solve in off-set printing and difficult to handle in full-on printing. Over the past 10 years, we have printed thousands of fully-open maps, ranging from single prints to multiple prints; both monochrome and multi-color printing; both offset and coated paper, silk, and Tyvek There are both civilian map products and military map products. The following is based on my many years of experience in making and printing various full-scale map prints.

One, large area uneven or uneven

The use of large-area flat screens in the fully-opened maps is the most common, such as the blue dyeing of the sea and the regional dyeing of the area, and the flat screen area is usually over 30%. Due to the large area of ​​flat screen printing, uneven and uneven dots often occur. These are:

(1) The unevenness of copies of film dots: Due to the uneven light source of the copying machine, poor suction, and poor development, it is often difficult to ensure uniform dot distribution when the film is opened. In particular, 50% Internet access points are available. Only by adjusting the copying machine Repeat copy. (With the advent of map computer graphics, such problems will gradually disappear.)

(II) Uneven light source or air suction is not tight: Due to the large area of ​​full-open map, the influence of light source and pumping around the full-open layout is particularly serious. Therefore, the aging of the light source should be replaced in a timely manner, the suction pressure should be greater than the open version, and there should not be any foreign matter on the rubber of the printing machine.

(3) The PS version has uneven coating or has horseshoe prints on the plate: The quality of the PS plate should be relatively stable, but due to different manufacturers, especially when the plate is opened, the quality of the plate is not ideal because the area is relatively small. In the past few years, the plates we purchased have horseshoe prints (generally produced during the handling process). The stupid approach is only solved with rubber hammers.

(D) rubber aging or uneven pad: slightly uneven pad or rubber mild aging, generally does not seriously affect the quality of the print or the naked eye is difficult to detect, but in full-on map printing, especially for large-area network printing is particularly prominent At the very least, black mesh or other dark-colored dots are particularly noticeable. In this case, it is usually necessary to re-pad or renew the eraser.

Second, inaccurate fitting

In the full-open map printing, due to its large format, in the printing of more colors, more pieces of paperwork and many types of paper, it is affected by factors such as the printing cycle, the temperature and humidity of the printing room, the adaptability of paper, printing equipment, and so on. Inter-set synthesis

The difficulties and focuses in full-scale map printing are:

(1) The multi-color machine units cannot fit together: uneven thickness of the printing plate, uneven or uneven printing of the printing plate, uneven or uneven rubber packing, and so on. Intermittent sets are inaccurate (I use the Japanese Hamada Daquan open two-color machine), then by appropriate adjustment can be resolved. Another factor that is not easy to find is the suitability of paper for printing. This is often the case with special paper or offset paper. However, coated paper can cause similar problems, such as the one we used in 1997. Korea (HONGWONPAPER) 128 grams of coated paper (perhaps counterfeit goods?), after several days of investigation and use of another brand of coated paper, the issue of fit between the group and the two groups naturally disappear.

(II) The second and third paper slips are not fit together: The map products have strict requirements for printing and fitting, especially the dual-line color printing of traffic maps, and the line and text color codes produced by computer graphics are even more difficult. Mastering that when the water is not properly taken, the temperature and humidity of the workshop is unstable, the climate changes abruptly, and the printing cycle is long, it will trigger the second and third paper feeds.

Therefore, in addition to the normal control of water and ink balance, temperature and humidity in the workshop, we should also fully consider the weather conditions and the determination of the printing cycle when printing with multiple images. When problems that are difficult to correct are encountered, they may also consider dividing the maps into different pieces. Because a certain color of the map product is discontinuous, when a certain color is not available, the color can be changed. Or print twice or even three times to ensure the accuracy of the fitting.

Third, the difficulties of multi-splicing printing

When a user needs a large-scale map and the area is large, it is often difficult to accommodate a full sheet of paper. This is the case in city maps and plan drawings. In this case, it is usually divided into two, four, nine, etc. Since these drawings are generally special drawings (figure), the number of prints is relatively small, and the number of prints is usually more. To ensure the entire effect of the mosaic after printing, attention should be paid when printing:

(I) Determining the number of prints at the same time: From the perspective of printing, multi-splitter maps are of course printed at the same time to better reflect the ink color of each frame, and maintain their accuracy and sensitivity. However, when the number of frames is large, such as eight or nine puzzles, it is necessary to ensure that the ink color is accurate and accurate and that the fitting is accurate. At the same time, the influence of temperature, humidity, and printing cycle on the print quality should be considered. In the climate stabilization season, four or five prints can be made at the same time, and two or three prints can be considered simultaneously when the rainy season and other changes are erratic. In the absence of daylight sources in the workshop, in order to make the ink color consistent, the printing should be arranged during the day so that the number of prints must be reduced accordingly.

(2) Arrangement of printing color sequence: Since there is no continuous tone change in map printing and the requirement for color reproduction is not particularly high, this determines that it does not need to follow the sequence of image printing. When the air humidity is relatively low, the main color printing can be arranged first, so that the paper can be returned to the original state when the paper is fed for the second time; when the air humidity is relatively high, a minor color with a relatively low requirement can be arranged first. Printing, so that even if the paper can not be restored to the original state when the second paper is fed, the quality of the map is generally not seriously affected.

Fourth, the difficulty of printing special paper

Silk maps, Tyvek maps and other waterproof, wear-resistant, anti-folding characteristics, so that they are favored in some areas. However, the silk fabrics can only be printed after being curled, and they are curled and deformed. Tyvek's texture is light, and its adaptability is poor. In addition, their printing costs are high, and the number of prints is small. Full-on printing is difficult to grasp.

(1) The printing of silk maps: The silk map is generally an offset paper over IOOG, and its quality is heavy and thick. In view of the characteristics of silk curling, pressurization should be carried out once before printing to ensure that the paper is stable during the formal printing. When the paper is fed, the air blower, the amount of suction air should be increased, and the double-sheet control height should be increased. At the same time, the printing pressure should be increased. Since the silk fabric is easy to penetrate the ink, the amount of ink transferred during printing should be adjusted to be large enough to prevent the map from being too pale after the paper is peeled off.

(b) Printing of Tyvekmap: Because Tyvek is a chemical fiber product made of high-density polyethylene blow-sprayed and heat-pressed, 70% of its volume is air, therefore, pressurization should be performed before formal printing. Take a walk once, otherwise, the first color and the remaining colors cannot fit together (actually due to pressure deformation). When the paper is fed, the amount of blowing and suction should be reduced. At the same time, the amount of water should be reduced to prevent the water from expanding and deforming, ensuring the accuracy of the fitting.

Full-on map printing, no matter from the perspective of printing equipment or printing process, is similar to ordinary printing, but anything except commonness has its own particularities, and full-on map printing is no exception. Therefore, in the full-open map printing should grasp its characteristics, targeted adjustment of printing process methods, solve the problems in the printing process, and constantly grasp its internal laws, in order to make full-scale map printing products to meet the requirements of various aspects.

Source: Print World