Offset printing to save ink
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Nowadays, the competition among printing companies is becoming increasingly fierce. In order to obtain printing business, many printing companies have fought price wars. As a result, the business volume of printing companies has increased, and the profitability of printing has become lower and lower. Many printing companies have realized this. How to improve the market competitiveness of enterprises by reducing internal costs, improving printing efficiency and print quality has become the focus of the industry. The cost of ink is important for printing costs. As a component, how to save ink is the core issue of these printing companies.
Offset printing should save ink and make a fuss before printing. This article mainly from the aspects of GCR/UCR process, ink preset technology, new screening technology, etc., talks about how to reduce ink waste and improve ink utilization by optimizing the prepress process.
1. Reduce the amount of ink by using GCR/UCR process
GCR refers to achromatic structure, that is, gray component replacement; UCR refers to background color removal. Both processes are used to replace the color ink with black ink in CMYK4 color printing, that is, to reduce the amount of ink of the yellow, magenta, and cyan primary color plates, and accordingly increase the amount of ink in the black plate, thereby achieving the purpose of uniform color. The theoretical basis for "replacement of colored ink with black ink" is gray balance. As shown in Figure 1, the color of 80% cyan, 71% magenta, and 71% yellow is equivalent to 80% black, so you can replace 222% (80%+71%) with 80% black ink when printing. +71%) total ink volume.
According to the principle of gray balance, it is possible to remove the color ink component which is added to form black, leaving the remaining part. To print 90% green, 76% magenta, 71% yellow, only 10% green, 5% product is printed. Red and 80% black can be.
In the printing production, using the GCR and UCR processes has the following advantages:
(1) Reduce the amount of ink, prevent the printed matter from sticking and sticking, and reduce the cost;
(2) Open the density contrast of the image and enrich the dark tone level.
It should be noted that the total amount of ink allowed for different printing speeds, presses and substrates is different, usually between a maximum of 260% (newspaper) and 350% (high-quality sheetfed presses). Therefore, only the correct use of the "GCR" and "UCR" color separation process, in order to limit the total amount of printing ink, print a rich and vivid color.
2.CIP3/4 ink preset technology
CIP3/4 ink preset technology refers to automatically calculating the ink data of different ink areas of the printing machine through the PPF file generated by the prepress digital workflow RIP, and then transferring the accurate preset ink amount to the printing machine through the CIP3/4 system. The amount of ink discharged is precisely controlled by adjusting the ink opening of the press. Through the CIP3/4 ink preset technology, it is possible to obtain a basic and accurate color proof after 20 to 30 prints, and then obtain the correct proof by appropriate fine-tuning, which avoids the traditional experience of chasing only by personal experience. A large amount of paper and ink waste. Based on the CIP3/4 standard ink preset technology, it can realize the transfer of preset ink amount data and maintain the stability of print quality.
3. Computer color matching system
The application of computer color matching system can help printing companies to accurately control the amount of ink and the quality of the distribution, reduce the total amount of waste, and thus reduce the loss of printing materials.
Modern computer color matching systems usually consist of a spectrophotometer and a computer equipped with a special program. The spectrophotometer measures the original color data of color samples, coloring matrices and pigments, and then gives a color scheme through computer operation. When there is a large color difference between the copy color and the target color due to the influence of raw material properties and process parameters, the computer color matching system corrects the used formula to control the color difference within the allowable range. The main color matching systems currently used are: Swiss CMC-2000 color matching system, Match-Mate computer color matching system, MM series computer color matching system.
4. Ink usage accurate calculation system
How to calculate the amount of ink to be prepared in actual production? If the amount of preparation is too much, a large amount of waste ink will be left after production, which will waste costs and increase the inventory of waste ink. If the budget is too small, employees will have to re-form, or even wait for the machine to stop production.
Generally, the amount of ink is affected by several factors: the print area, the number of prints, the ink loss rate, the minimum amount of ink on the press (the amount of ink required for normal printing), the thickness of the ink layer, and the density of the ink. The accurate calculation system of ink dosage can comprehensively consider the above factors and automatically calculate the total amount of ink. The calculation formula is as follows:
Single print ink usage = printing area × ink thickness × ink density (1)
Total ink consumption = single printing ink consumption × (1 + loss rate) × total printing + minimum ink usage (2)
The printed area in equation (1) can be calculated from CIP3/4 ink preset data, and other parameters can be calculated based on actual print production.
5. Using new screening technology to reduce the amount of ink
In order to save ink consumption, some new screening technologies have emerged, such as the concentric circle screening technology invented by ESKO. The concentric circle screening is to change the exposure point of the amplitude modulation network dot, so that the dot is a small circle. Like the AM grid, the arrangement of concentric circles is the same, but it consists of two parts: the exposure circle and the blank circle. The width of the exposure circle can be changed by setting different parameters.
Concentric dots can bring many advantages in terms of cost savings and print quality. Here we focus on the impact of concentric dots on ink usage.
Obviously, the AM dot is used to remove a large amount of ink after inking, and the amount of ink retained by the concentric dots is relatively small, which is determined by the size of the dot substrate. At the same time, in the actual printing process, the supply amount of the ink is increased, and the dot of the large substrate may accumulate a large amount of ink, and when the dot of the small substrate reaches the critical point, the thickness of the ink layer is not increased. At the same time, even if there is a dot increase, the inward dot gain may partially cover the blank area, so that the real dot coverage area reaches the desired dot coverage value. Therefore, the use of concentric circles can achieve the purpose of saving ink.
In terms of saving ink consumption, it is necessary not only to ensure that the printing machine is in a stable working state, to ensure the stability of the environment and printing materials, but also to start from the pre-pressing section, and to carefully calculate the nuances, in order to reduce the ink consumption and save production costs. Make the company more competitive.