Correctly outputting four-color film film is critical, and its quality is related to the final effect of the printed matter. Therefore, the trend in the printing industry today is that a good design production person will only engage in creation and design. It is not enough to have output. A series of knowledge to avoid the waste of human and material resources due to the operation problems of the producer or the mistakes of the exporter in the production process. This phenomenon is common in production practice. We often encounter such problems in practical work. We urgently need to look at large-scale advertisements, but we cannot find out in the output center, or the films do not meet the requirements, resulting in a series of production interruptions. , causing irreparable damage to customers and printing plants. Therefore, starting from the actual production, I summed up some of the problems that often arise in the film output process and solutions.
1. Regularly calibrated machine
When exporting the film, it is first necessary to ensure that the laser imagesetter is in an absolutely normal and good working condition and that the laser imagesetter is regularly calibrated. This is the basic premise of all work. From the perspective of optimizing the operations of the imagesetter, periodic calibration of the equipment ensures that the equipment produces the correct film density. A small problem with the photo-composing machine may cause the waste of the film and the lowering of the efficiency of the film. It may also cause the film bottom ash to be too large, the density is not enough, the layout is not uniform, the field is not true, the level is lost, the net is missing, the paste version, etc. phenomenon.
2. Ways to increase the output efficiency of the imagesetter
1 Sometimes changing the direction of the photo page can greatly increase the imaging speed. For example, pages such as letter paper, with the long edge in the axial direction during exposure imaging, save both exposure time and material.
2 Firstly image the successful job, temporarily remove the problematic job, and finally deal with the problematic job.
3. Problems that should be noticed when photosetter output film
To output high-quality platemaking negatives, in addition to setting the output parameters correctly, the corresponding technical measures must also be taken according to the characteristics of the photocopies. Therefore, it is necessary to understand and understand the technical requirements of the photocopies.
According to the different characteristics of the light source of the imagesetter, the laser photofinishing film is generally divided into two types, namely HN and red laser LD. The direction of the film side is divided into inward or outward, and one phototype machine can only use the inner or outer roll. One of the films. The film used in the phototypesetting machine has two kinds of axis size, the small axis is 2.0 inches (5lmm), and the large axis is 2.8 inches (71.9mm).
Each imagesetter can only use film whose width is smaller than its maximum size. The length of the film that the imagesetter can install is determined by the size of its cassette.
1 Although the usual photocopying film is a bright room film, the loading process can be completed under the indoor light source, but in the actual production should still strictly abide by the operating procedures, according to the requirements of the film into the loading box, close the cover, Tighten the screws on both sides of the box (note that both sides are balanced with equal force), and then tear the film lead so that the exposed film on both sides of the film is parallel, the width of 1.5 ~ 2cm. Hold the bottom of the box during handling to prevent the film from being exposed due to falling off.
2 Before each batch of laser illuminating film is put into use, basic density testing and linearization of the dots shall be performed. Then, corresponding technological measures shall be taken according to the test results, such as adjusting the laser focal length, exposure amount, developing and fixing temperature and time. Achieve standardized and scientific production to prevent the production of substandard products.
(1) Film density is divided into high density and low density. Low density refers to the density at which the film is completely unexposed after rinsing, typically around 0.05. The lower the low density, the more transparent the film is and the better the quality of the printing screen. High density refers to the density of the film after it has been washed at 100% exposure. The printing film used in traditional coated paper requires a high density value of not less than 3.5, usually 3.5 to 4.5. This ensures that the image information on the film is well transferred to the printing plate during printing. When printing on newsprint and offset paper (including map paper), the high density of the paper may be appropriately reduced due to the strong ink absorption and high printing speed.
(2) Linearization refers to the process of color separation. It is required to ensure that the dot values ​​set in the computer can be truly reflected on the printed film. Take 50% neutral ash as an example, the requirement for 50% dots on the computer graphics must be 50% on the printed film, and the dot error should not exceed ±1%. Otherwise, the distortion of the printed image will be caused. This is especially evident in color four-color printing. However, it is difficult to ensure the stability of the film development and fixing conditions. Therefore, it is more stringent to perform linear sampling on a daily basis.
3 Adjust the developer concentration, temperature, and fixing time.
(1) Other conditions remain the same, the developer "target="_blank"> The higher the developer concentration, the higher the temperature, the higher the density of the film.If you use domestic developer (eg: Aibixi SH-1000 ) Flushing the film, the liquid is generally diluted 1:4 to 1:3, it is necessary to pay attention to the high development temperature will make the developer due to evaporation, the oxidation rate is too fast and failure, resulting in high film fog, while The high density does not meet the requirements.The recommended temperature is 34-36°C, and the density and linearization are measured again when the development temperature is stable and the set temperature is reached.
(2) Other conditions remain unchanged, the higher the fixing solution concentration, the higher the temperature, the lower the film base fog (low density), the dilution ratio of the domestically produced fixing solution is 1:4, too high fixing temperature setting (or excessively high temperatures in summer) can cause the fixing fluid to fail due to evaporation or oxidation too quickly, resulting in excessively high film haze. At the same time, the high density may not meet the requirements, and liquid crystals of the liquid may adhere to the fixing roller. The film is scratched. Therefore, the fixing temperature is 28 to 32°C, and the fixing time is 30 to 35 seconds.
4 The laser photocoiling film contains an anti-halation layer, some of which will fall off in the process of fixing and washing, forming a light blue water spot on the film base, which can be eliminated by adding an appropriate amount of hardener in the fixing liquid. The washing tank must be kept clean. After the work is completed, the water in the sink should be drained and wiped with a clean gauze. Before each water addition, remove some water to remove rust, and at least stick to the water roller once a week.
In short, only by correctly grasping the characteristics of the laser photocolumn film, and correctly putting the output technology and operation technology in order to effectively ensure the quality of the laser photocopying and improving the output efficiency.