Adopting wide width flexo printing machine -- the best choice to realize the pre printing process of corrugated boxes
in the face of the rapidly expanding corrugated box market with increasingly high printing quality requirements, many domestic corrugated box enterprises are constantly improving the original equipment and technology, looking for more suitable new equipment and technology, hoping to meet the market requirements for the quality of corrugated boxes on the basis of reasonably increasing the input cost, So as to continue to survive and develop in the new round of competition. In previous years, some enterprises used gravure printing machines to print the outer packaging paper of the corrugated box, and then directly used it as the finished face paper of the corrugated box to form it in the corrugated paper production line at one time - we call this process "corrugated box pre printing process". Now the gravure press used for this purpose is called corrugated preprint gravure press in the market. This concept is inaccurate. Because this gravure printing machine refers to the ordinary paper gravure printing machine, and "pre printing" is a new process to improve the printing quality of corrugated box manufacturing, rather than the printing equipment
at this stage, "pre printing process of corrugated boxes" is indeed the only and most effective way to improve the printing level of corrugated boxes. There are many ways to realize it:
a. you can use multi-color printing such as sheet fed offset printing machine, sheet fed wire printing machine, sheet fed intaglio printing machine, sheet fed flexographic printing machine, and then stick with corrugated paper (using veneer machine), slotting die cutting (slotting machine), which can realize the "corrugated box pre printing process" to manufacture corrugated boxes
b. multi color printing can be carried out by using web offset printing machine, web gravure printing machine, web flexo printing machine and other printing equipment, and then directly formed with the corrugated production line at one time, or the "corrugated box pre printing process" can be realized to manufacture corrugated boxes
in view of the above options, corrugated box enterprises can decide which other amputees including several others can be used to realize the "corrugated box pre printing process" according to the different requirements of customers and their own strength. I think the enterprise must take into account the development of the enterprise itself, the development and changes of the market, as well as the different requirements of corrugated box quality, cost, delivery cycle, etc., that is, the best choice for our enterprise is to use which printing method to realize the "corrugated box pre printing process"
the selection of "pre printing process of corrugated box" is actually the selection of which paper printing machine is used to print the surface paper of the box. Therefore, it is necessary to understand and compare the equipment cost, use cost, printing adaptability, equipment auxiliary process, etc. of the printing machine, so as to select the "corrugated box pre printing process" that is most suitable for the enterprise
here we analyze the equipment, effect and process performance of the wide flexo press when it is applied to the "corrugated box pre printing process", so that the large and medium-sized corrugated box manufacturers in development can take it as a reference when they decide to use the "corrugated box pre printing process"
I. equipment requirements for the wide flexographic printing machine applicable to the "corrugated box pre printing process"
the wide flexographic printing machine applicable to the "corrugated box pre printing process" is actually one of the ordinary flexographic printing machines, just to better adapt to the special requirements of corrugated box pre printing, including printing width, printing width length, line and field, plate thickness, automatic control of paper roll in and roll out, material cutting Reasonable combination of technical parameters and configuration of the whole machine automation control degree. The following technical parameters and configuration instructions are recommended for discussion
(I) main performance index parameters and descriptions
1 Printing type - the selection of the equipment type of the unit
flexographic printing machine is mainly determined according to the market requirements faced by users and the main parameters of the equipment. Due to the significant improvement of current equipment manufacturing technology and system control technology, there is no problem of who is better or worse in terms of printing quality, printing speed and technical grade for unit type, satellite type and cascade type. The difference lies in how to meet user requirements and control equipment cost. In high-grade flexo printing equipment, the use, maintenance and equipment manufacturing costs are different
the unit type is easy to use and maintain, and the center of gravity of the equipment is low, which is conducive to reducing the plate rolling balance during high-speed operation. At the same time, it has great space advantages for large plate rolling (referring to plate diameter greater than 500mm) and multi-color group printing adaptability (referring to more than 6 colors), and it is easy to install the full-automatic tension control system and the vertical and horizontal automatic overprint system. However, due to the long path of printing paper, the requirements for equipment manufacturing and installation accuracy and tension control technology of the whole machine are higher than those of satellite type and cascade type, and the equipment cost is slightly higher
the advantages of the satellite type are mainly due to the common impression cylinder, short printing paper path, relatively simple control system and low manufacturing cost of the whole machine. However, it is relatively inconvenient to use and maintain. For large plate roller and multi-color group printing, the embossing roller is too large, so it is difficult to ensure its manufacturing and installation accuracy. There are also many difficulties in transportation and maintenance (for example, the height limit of expressway is 4.5m); At the same time, its structure is not easy to install the full-automatic tension control system and the vertical and horizontal automatic overprint system, the drying oven is short, and the flexibility of adding other functions is poor. The advantages and disadvantages of the cascade type lie between the unit type and the satellite type. When the printing speed and printing quality are not high and the degree of automation of the equipment is relatively low, it is the best choice for paper printing, so it can greatly reduce the manufacturing cost of the equipment
2 because most springs are the main components used in machinery and vehicles Printing color number - 6-8 colors
now corrugated boxes are generally four-color printing, which is largely limited by the type of printing equipment (sheet fed paper). For printing after the corrugated paper is formed, it is difficult to control the printing pressure and registration. The more color groups, the more chances of printing quality problems. As a unit flexo printer, the number of color groups should be considered for carton pre printing (3-4 colors for pattern overprint, 2-3 colors for field, 1 color for reserved glazing, etc., so that the colors are rich and the layers are clear, and separate glazing and other processes can also be avoided). I think at least 6 colors or more should be selected. For example, the gravure printing machine for flexible packaging printing in China began to develop from 4 colors, and developed to 6-8 colors in a very short time (2-3 years). At present, users of medium and high-end products generally require that the number of printing colors be about 8-10, and the maximum is 12-14
3. Printing speed - 130m/min-150m/min, 180m/min-200m/min
printing speed is mainly considered from the aspects of equipment manufacturing cost, use cost, the level of domestic printing machine manufacturing enterprises at the present stage and the investment capacity of corrugated box enterprises. Because corrugated boxes have large preprint width, large printing plate roll diameter, high requirements for tension control technology, and high requirements for the automation of winding, unwinding, cutting and refueling, if the speed is high, the corresponding manufacturing cost will increase significantly, and the cost of paper and ink will also increase correspondingly. Therefore, it is suggested to use 130m/min-150m/min model in the initial technical transformation, so as to better master the flexo printing technology and process and cultivate professional talents; Reduce the use cost of paper and ink, and accumulate experience in flexo printing process and use; At the same time, due to the low labor and site costs in China, we can use overtime or increase equipment to solve the problem of work efficiency. When the printing quality is further improved and the production efficiency is accelerated, the 180m/min-200m/min full-automatic high-grade model can be introduced. Because of the high speed, the automation degree, printing quality, equipment configuration and raw material saving of the equipment will be improved to varying degrees
4. Printing width: 1600mm wide and 800mm ~ 1600mm long.
the printing width and length are mainly determined by the size of corrugated boxes and the number of boxes overprinted at a time. In this way, we can better save wood. The corrugated box is generally a large box with a width of more than 1000mm, so the minimum width is set at more than 800mm, which can fully meet the requirements of corrugated paper. At the same time, there is a large size of the mounting base of the plate roll. Because the weight of the large plate roll (with a diameter of 500mm) is large, there must be a large base structure to ensure, but the difference between the bridging and foaming time cannot be too large. Its stability and the rigidity of the mounting journal. From the perspective of the domestic carton industry, 1600mm printing width can not only meet the requirements of the largest corrugated carton, but also facilitate overprint and cutting of multiple small boxes
5. Requirements for printing quality
narrow width (below 660mm) unit flexographic printing machine the national industry standard "flexographic printing machine" (JB/t-10480-2004) stipulates the following requirements for printing quality: the printing registration error is within 0.25mm, and the qualification rate of continuous samples shall not be less than 96%; The stability deviation of monochrome field printing shall not be greater than 0.06mm; The uniformity deviation of field printing and stamping shall not be greater than 20%; The maximum speed of the machine is 150m/min. The domestic narrow width unit flexo printing machine is mainly used for trademark printing, high-grade carton printing, cigarette packaging printing, etc. the requirements for printing quality and packaging added value are higher than those of corrugated cartons in all aspects. Therefore, the requirements for corrugated paper printing quality should be determined after comprehensive consideration of equipment cost and product production cost: the printing registration error should be within 0.25mm, and the qualification rate of continuous samples should not be less than 96%; The stability deviation of monochrome field printing shall not be greater than 0.08mm-0.10mm; The uniformity deviation of field printing and embossing shall not be greater than 25% - 30% (due to the large reduction of format)
6. Maximum unwinding and rewinding diameter - φ The determination of the diameter of the reels in and out of the 1200mm ~ 1500mm
web printing press should comprehensively consider various factors. Comprehensive corrugated box packaging and printing, too small diameter, too many joints, large waste of finished products, too large diameter, heavy weight, difficult tension control, difficult loading and unloading, and greatly increased the cost of automatic cutting and refueling mechanism and rewinding mechanism. Therefore, the recommended range is φ 1200mm ~ 1500mm is appropriate
7. Parameters of main printing parts
the main function of corrugated box outer packaging printing is the visual effect of medium and short distance, and it is used once in a short time, so users must consider this factor in pattern design. The printing line is mainly divided into two parts: fine (overprint) and rough (on-the-spot). The overprint part is mainly fine. Jinan new era assaying Instrument Co., Ltd. believes that everyone knows that rubber is a pattern with a level of elongation, so the printing line is required to be high. Generally, the reproduction and restoration line of printing is about 80lpi-120lpi; The field part requires a large amount of ink transfer, and the print itself is wireless. In this way, we can select the plate thickness, plate making line and wrinkle roll line. To reach the printing copy reduction line 80lpi-120lpi, the plate thickness should be 2.28mm or 2.84mm; Plate making line 100lpi ~ 150lpi; Number of wrinkle roll lines - pattern wrinkle roll 400lpi ~ 600lpi, field wrinkle roll 150lpi ~ 250lpi. Excessive requirements will increase the printing cost, and the printing effect may not be as good as the low line
(II) configuration and description of main parts
1 The unwinding and rewinding part
because the paper is wide and heavy, any pause or interruption in the printing process will need a period of time to re run until the tension is stable, resulting in an increase in printing defects. Therefore, the main configuration requires no shutdown, no speed reduction and automatic cutting. The paper roll must be equipped with motor drive and brake,