Comparison of large-scale field printing between t

2022-08-12
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Comparison of large-scale field printing between single concave press and domestic two-color offset press

with the rapid development of market economy, the packaging of goods is becoming more and more important. It has become a consensus that exquisite packaging can improve the grade and sales price of goods. Therefore, commodity manufacturers have higher and higher requirements for the quality of packaging and printing products

large area spot color field is a commonly used means of contrast and rendering in commodity packaging design. It is an important form to reflect the image of commodity shelves, and it is also the difficulty of printing and reproduction and the key point of quality control

in China, offset printing is one of the main ways of paper packaging printing. The technology is mature, and it can copy very fine products, which can meet the public consumption psychology of our market, so the popularity rate is very high. Sheet fed gravure printing is a rising printing method in recent years, which is unique in spot color and field printing, and it is quite flexible to use. According to the business needs, our factory purchased the sheet fed gravure printing machine produced by Beijing zhenhenry Printing Machinery Co., Ltd. and used it together with the original offset printing machine, which achieved good results in packaging and printing

this paper intends to analyze which equipment is more suitable for sheet fed gravure printing machine or domestic two-color offset printing machine with regard to large-area field packaging and printing

due to the characteristics of the machine itself, the operation of the single concave machine is very simple. The paper feeding part and the paper receiving part are the same as the offset press. Generally, people who can operate the offset press can operate the single concave machine without special training. The main difference between sheet fed gravure printing and sheet fed offset printing lies in the difference of printing plate and ink used

from the perspective of printing plate, at first glance, it seems that the cost of gravure printing is high, but it is not necessarily true. Because gravure plates have high printing resistance, the general commitment of plate makers is to reach at least 1million printing times, while the printing volume of packaging prints is generally large, and they often need to be printed repeatedly. Therefore, in the long run, the plate making cost difference between gravure printing and offset printing is not great in printing large-area field packaging products. In addition, the quality of gravure printing plate is very stable due to the influence of external factors. It is very convenient to install the plate on the single concave machine. After normal printing, as long as the ink viscosity is kept without too much deviation, the whole printing process will be very smooth, and the printed matter is easy to keep the ink color consistent

from the perspective of the ink used, the cost of gravure printing ink is similar to that of ordinary resin offset printing ink, but gravure printing ink has the characteristics of low viscosity and good fluidity. Due to the use of a large number of volatile organic solvents, the printing ink layer can be quickly dried under the infrared light of the drying part of the gravure printing machine, and there is no problem of printing stickiness. After printing one color, the next color can be printed immediately, or it can be transferred to the next process for post press processing

if the offset printing process is adopted, if the ordinary resin ink is used, the ink cannot be completely dried on the printing machine, and it is necessary to spray powder on the paper receiving part to prevent the printed matter from sticking dirty. A slight mistake in powder spraying control will cause the printed matter to be sticky and dirty, resulting in higher scrap rate and lower production efficiency. Because the oxidation polymerization drying of ordinary resin ink takes a long time, the printed product cannot be reprinted or processed immediately, and it needs to be placed for a period of time until it is fully dried. Although the use of UV ink can eliminate all kinds of disadvantages in the drying process of offset printing products, the printing cost will increase a lot. Even without considering the cost of installing UV curing device, only the cost of ink, UV ink is about 10 times that of ordinary offset printing ink

the large-area field printed by the single concave machine has bright color, saturated hue and thick ink layer. If the single concave machine is used for waterborne or UV glazing, the color effect will be better and the wear resistance of the ink layer will be better. The offset printing process is used to print a large area of the field. If ordinary resin ink is used, it is usually printed twice to barely meet the customer's requirements, but the ink solution: the layer is thick, it is difficult to dry, and a large amount of powder spraying is required to prevent the printing from sticking dirty. The structure is compact: the interface is modular design, resulting in rough and matt surface of the ink layer, and the brightness after polishing is also difficult to meet the requirements. If the post process also needs to carry out anodized hot stamping, it will cause hot stamping difficulties. A large amount of powder spraying not only affects the printing quality, but also adds difficulties to subsequent operations. In addition, the use of two-color offset printing machine is also prone to ink color differences, field colored lines and other problems

zhenhenli single concave machine adopts an uninterrupted circulating ink supply system on the ink supply. As long as the ink viscosity is well controlled, the ink viscosity will not be affected by external environmental factors during the printing process of the whole batch of products, and the ink color before and after the printing of the whole batch of products is very stable

due to the balance of ink and water in offset printing, it is difficult to achieve the same ink color in front and back prints. After all, the ink level and water level change all the time. In particular, when printing after shutdown, the ink color changes more, and the ink color must be adjusted by adding and releasing the master paper frequently. When using gravure press, you don't need to put in the master paper, and then print after shutdown, you can immediately obtain the ink color consistent with the previous print. In this way, the qualified rate of printed products will be greatly improved compared with offset printing, reducing paper consumption and naturally saving printing costs

from the perspective of applicable paper, the single concave machine has wider adaptability, while the offset press is not suitable for printing non absorbent materials, such as gold and silver cardboard. Because the surface of the gold and silver cardboard is very smooth, the ordinary offset printing ink cannot adhere well on its surface, which is prone to thinning of the ink layer and uneven inking, and the printed ink is also difficult to dry; Even if it is dry, the problem of ink layer falling off is inevitable

with the fierce market competition, consumers are becoming more and more picky about commodities, and commodity packaging has to develop towards high-end to improve the competitiveness of commodities. The application proportion of gold and silver cardboard and glass cardboard is constantly increasing, and it is difficult to adapt to the ordinary offset printing process. Gravure printing should be the first choice when printing high-grade gold and silver cardboard packaging

from the above rough comparison, it can be seen that when printing large-area field packaged prints, the comprehensive cost of using a single concave machine is similar to that of using a domestic two-color offset press, but in terms of printing effect and production efficiency, using a single concave machine is better than using an offset press

next, take a cigarette packet printing example to compare and analyze the combination process of full offset printing and glue concave, see the attached table

comparison of large-scale field printing

print: Jiangxi Gannan tobacco factory "special quality GaN cigarette" cigarette bag

model: beiren j2204 offset press, zhenhenri four-color, monochrome single concave machine

operator configuration: 3 people for domestic two-color offset press and 2 people for sheet fed gravure press

printing material: 250g/㎡ white cardboard

print specification: 540mm × 740mm, 15 small pieces

printing process: full offset printing, combination of offset printing and gravure printing

ink: Standard magenta, yellow, black ink, spot color red ink, coffee spot color ink, thermochromic yellow ink

the general manager of railway has also intensively started polishing 14 projects: local polishing is adopted for printing, and the polishing area is 0.294 ㎡/sheet

through comparative analysis, it is concluded that the advantages of glue concave combination process over full offset printing process are as follows:

1 The labor intensity is reduced, and the operation of the single concave machine is simple. The domestic two-color offset press needs 3 people to operate, while the single concave machine only needs 2 people to operate. Based on the monthly salary of 1500 yuan for each operator, the omission of an operator will undoubtedly bring additional benefits to the enterprise

2. Improve production efficiency. It takes 15 minutes to install the plate on the single concave machine, 10 minutes to calibrate the plate, and then 5 minutes to adjust the viscosity of the circulating ink, which can be produced normally, 15% faster than the startup preparation of offset printing. After normal printing, it can be printed continuously at the speed of 6000 sheets/hour. The single concave machine still has no problems such as cleaning the blanket, cleaning and turning off the power supply of the operator and removing paper wool and white spots from the impact motor source. The printing time saved per shift is 1.5 hours, which is 1.7 ~ 2 hours in total, including the time saved during plate loading. Each shift can increase output by 6000 × 2 = 12000 (sheets), 15 small pieces for one printing sheet

3. The waiting time for the next process is greatly shortened. We can take advantage of the increase of unit time production capacity to develop more new businesses, save time for equipment maintenance, save overtime costs in peak seasons, and shorten the product cycle, so as to further improve the competitiveness of enterprises in the market

4. The single concave machine does not need to spray powder. The ink is dried by infrared ray, and the electricity cost is basically the same as that of the powder spraying material required for offset printing. After water-based polishing with a single concave machine, the smoothness and wear resistance of the printing surface are improved

5. As the gravure ink layer is instantly dry, there is no sticky dirt (back printing) phenomenon, so waste products are reduced

"special premium Gan cigarette" cigarette packs did not appear a sticky waste after switching to single concave machine printing spot color red and coffee spot color, and the defective product rate was greatly reduced, thereby improving economic benefits. (end)

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