Standardization and dataization of newspaper printing
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Due to the timeliness of newspaper printing, standardization and data production have been difficult to achieve in newspaper printing houses. If newspaper printing can also form a standardized production model like lithographic offset printing, it not only saves time, but also contributes to the improvement of printing quality. In the following, we will discuss the standardization and dataization of newspaper printing from the aspects of film output, printing and printing, and printing for your reference.
Standardization and dataization of film output
At present, the film output of most printing houses has formed a standardized and data-based production mode. However, in actual work, due to the influence of personnel quality, equipment stability, management system and other factors, some links do not really reflect standardization. The connotation of data. In the printing house, the film output is generally carried out as follows: First, the imagesetter and the puncher are turned on, and after preheating for 30 minutes, the 21-step gray scale film is output. Then, use a dot densitometer to check whether the values of the dots on the film are within the specified range. If appropriate, start normal operation; if not, re-adjust the development conditions and repeat the output of the 21-step gray scale film. However, the daily printing volume of the newspaper printing house is quite large, and the film that has just been outputted is relatively normal. As the output of the film continues to increase, the concentration of the developing solution gradually decreases, although the developer replenishing device is functioning, but with development As time goes on, the development quality of the film also decreases. Due to the heavy work tasks, in order to ensure that the task is completed on time, the operator often does not handle it, or simply adds a certain amount of developer directly to the developing tank to continue working. Some operators even take the way of increasing the development and fixing temperature to speed up the development process to complete the production task on time.
Film is the basis of printing. If the film quality is not good, it is difficult to guarantee the final print quality. From the situation described above, the main factor affecting the output quality of the film is the punching process. In most newspaper printing factories, due to heavy tasks and tight time, the film processor is always in an overload state. To this end, the printing factory should increase the number of punching machines according to their actual conditions to ensure the stability of film quality.
Standardization and dataization of imposition and printing
Although many newspaper printing companies have already used CTP systems, due to the high cost of CTP equipment and high cost of printing plates, not all newspaper printing uses CTP plate making, and conventional manual imposition and printing processes still dominate.
The standardization and dataization of imposition is relatively easy to implement. It is only necessary to draw the standard imposition coordinates (paper), and the imposition personnel can construct according to the sample. However, for the printing plate, the amount of tasks in the relative time is super saturated. In order to ensure the timeliness, the workshop has to sacrifice the quality at the expense of extending the exposure time to achieve the purpose of removing dirt; on the other hand, increasing the concentration of the developer and speeding up the development to increase the production speed. Therefore, after the printing, the small dots are seriously lost, and the outlets below 5% cannot be exposed, resulting in a large area of the high-light area in the printing, which affects the printing quality of the newspaper.
In fact, the standardization and dataization of the printing plate is relatively easy to achieve. As long as the standard exposure time and development time are measured, the staff will strictly produce according to the requirements, and there will be no problem. However, due to the concentration of tasks in many newspaper printing houses, equipment is often not enough. To fully realize the standardization and dataization of the printing plate, it is necessary to increase the plate making equipment and operators, which is an urgent problem that most newspaper printing companies need to solve. At present, many newspaper printing houses pay special attention to the investment in printing equipment and the cultivation of printing talents, but they are not willing to invest more in the reform of plate making equipment and the introduction of plate making talents. Over time, the situation of "excessive printing capacity and insufficient plate making ability" has been formed. Therefore, even if the printing equipment is advanced, it is impossible to obtain high-quality newspaper prints.
Standardization and dataization of printing
Control of the printing process is the most complex and involved factor in the entire newspaper printing process. The performance and quality of the raw materials used, overprinting, printing pressure and printing environment will affect the standardization and dataization of the printing process.
1. Raw material
In the production process, the same type of photosensitive materials, PS plate, paper, ink and other raw materials should be used as much as possible to ensure the consistency of plate making and printing parameters, and provide a data foundation for color reproduction. At present, many newspaper printing houses have passed the ISO9000 quality system certification, and the incoming inspection of materials has been implemented as a daily routine. Therefore, to ensure the publication time and printing quality of newspaper printing, the incoming inspection of raw materials must be strictly carried out in accordance with the regulations, the quality is closed, and the generation of non-conforming products is eliminated from the source.
2. Ink and fountain solution
The principle of offset printing is ink and water balance. Therefore, controlling the ink balance is the basis of offset printing. If the amount of ink is large, it will inevitably require more water, otherwise it will paste the plate; if the amount of ink is small, it will inevitably require less water, otherwise the layout will be gray. Therefore, mastering the right amount of ink and water is the key to newspaper printing. How to balance the ink and fountain solution? The author believes that we should start from the following points.
(1) Make a standard color header. The density value of each primary color plate is measured by a densitometer during printing, and compared with the density of the standard header, and corresponding adjustment is made to ensure the consistency of the ink color of each newspaper header.
(2) The density value of the specified heart text. In the national standard for newspaper printing, the density value of the word "" in the small book No. 5 is used as the standard, and the standard density value is 0.25 ± 0.05.
(3) Partition the layout and measure the density of the words in the same font size in different locations to keep them the same, thus ensuring the same color of the entire layout. For example, 4 open layouts are divided into 8 zones, and 8 open layouts are divided into 4 zones.
(4) According to the actual situation of the enterprise, the solid density values of the standards Y, M, C, and K are specified and tested during the production process. As specified in the national standard, the field density values of Y, M, C, and K in newspaper printing are 0.60 to 0.80, 0.90 to 1.10, 1.0 to 1.20, and 1.0 to 1.30, respectively.
(5) Strictly control the proportion of dampening solution to ensure consistency of dampening solution during printing.
(6) Under the premise of ensuring no paste, print with the least amount of water supply, and once the amount of water is determined, it should be relatively stable.
3. Overprinting
Whether the overprinting is accurate is the most direct manifestation of the quality of the printed matter. Because of the speed of newspaper printing, it is inevitable that there will be overprinting errors, but there must be a standard. If it exceeds the standard range, it will be a non-conforming product. According to national standards, the overprint error of the main part should be within 0.5mm.
4. Printing pressure
Proper printing pressure is a prerequisite for smooth printing. The pressure is too large, the outlet is deformed, and the flat net is not flat; the pressure is too small, the outlet is faint, and the texture is not strong. Due to the single print, the newspaper printing company always uses newsprint printing, and the standardization of printing pressure control is easy to achieve. In the past, some old-fashioned printing presses used pressure to measure the pressure by pressing a "fuse" and inserting a "spacer". Nowadays, the machine only needs to measure the paper thickness with a vernier caliper and input the data into the computer, which can automatically adjust the pressure.
5. Printing environment
Printing has higher requirements on ambient temperature and humidity, and too high or too low temperature and humidity will have a certain impact on the printability of paper and ink.
In addition, many advanced imported equipment are also very strict with environmental temperature and humidity requirements. When the room temperature exceeds 30 ° C, the machine cannot be started due to poor heat dissipation of the motor and the electric cabinet. Therefore, the temperature in the workshop is generally controlled at 23 ± 5 ° C, and the relative humidity is controlled at 50% to 75%.
Only in the above aspects of the strict control of newspapers, the standardization and dataization of newspaper printing can be realized in actual production, and actually improve the printing quality of newspapers.