In the past ten years, many new technologies have emerged in flexo printing, such as closed squeegee kits, ceramic anilox rollers, gearless servo drives, uv printing, high pigmented inks, thin plate printing and digital plate making technologies, etc. The steady improvement in the quality of flexographic printing. Domestic flexographic printing applications have seen significant growth in the packaging of liquid packaging boxes, paper cups, folding cartons, beverage packages, milk cartons, and cigarette labels, as well as flexibility in paper, adhesive labels, plastic films, and aluminum foils. Substrate printing also uses a flexo process.
The most prominent aspect of the flexo printing process is the on-line production of flexographic printing presses. The production line includes processes such as coating, indentation, bronzing, and die cutting. In addition, offset, gravure, and screen printing units can also be incorporated into the flexo printing unit in modular form. In-line flexo printing process, due to the reduction of operating process, improve production efficiency and reduce costs, these advantages are fully demonstrated in the actual production.
The advantages of flexo printing can be clarified from the following aspects:
First, the reduction of raw material costs
Flexographic printing is a web-fed process, so it has the following advantages:
1. The purchase price of web is 4 to 6% less than that of a single sheet.
2. Sheet-fed printing requires 10 to 12 mm of mouthpieces and 2 to 3 mm of tipping edge for each sheet of paper, and the web does not require this edge to save about 2 to 3% of the total paper.
3. Such as the use of flexo printing, due to the water-based ink is less exposed, foreign flexographic presses originally used 52 grams of paper, has changed to 46 grams, saving 10% of the paper.
4. After the machine is shut down, the anilox roller can pass the ink in one or two turns of ink to reach the standard. Compared with the offset printing, it is necessary to print 4 to 5 sheets of paper to achieve the standard, which also reduces the generation of waste sheets.
Second, on flexo line production
The integration of different printing technologies and processes into the production of an in-line flexo press will yield integrated production results that will yield good economic benefits. Compared with stand-alone operation, the production cost is greatly reduced. Specifically include:
1. After surface glazing and laminating, the special machine for polishing can be saved, which not only reduces equipment investment, but also saves operator's expenses and can obtain high profits.
2. After the bronzing, embossing, embossing, die-cutting, and decantation processes are integrated for production, in addition to the advantages described above, the installation and operation of machinery and equipment, as well as the logistics transportation and stacking between processes, are also saved. Labor productivity has greatly reduced labor intensity.
3. Flexo printing on-line production, including offset printing units, gravure printing units and silk screen printing units between the units. A printing product is mixed and printed in several different ways. The product has a variety of features and good picture quality, and more security features. Simple and economical to meet customer requirements, with less investment and good results.
4. Integrated production makes production preparation and production planning processes extremely simple. The short processing cycle combined with high-speed production means that the extremely short response time to the order makes the delivery more rapid, more timely and more accurate, and it is more advantageous to solicit customers.
5. In-line production reduces the costs of staffing, product storage, and logistics, eliminates excessive storage, reduces the amount of liquidity used, facilitates the investment in corporate reproduction, and brings vitality to business operations.
Third, the advantages of flexographic printing technology
The flexo printing process is different from other printing processes. Flexographic printing shows certain advantages in terms of production cost, economic benefits and social benefits.
1. Flexographic printing has the strongest adaptability to printing materials, whether it is paper, composite materials, adhesives, gold and silver aluminum foil, various plastic films or even corrugated cardboard, regardless of its thickness, thickness, and surface ink absorption properties. Can be widely adapted. Many types of printing are not comparable to any kind of printing methods. Although it is not possible to print a variety of printing materials on a single machine, a good printing effect can usually be achieved by using a flexo printing method.
2. The printing pressure in the flexographic printing process (because the plate material is flexible and flexible) is very small (known as: zero pressure), and the stability of the ink amount on the screen roller net is excellent, so it is possible to print excellent The products, such as China's participation in the international quality evaluation of flexo printing in 2010, won the Bronze Award with a snowscape image printed on a 202-line network cable. In 2005, Jinsheng Tang's folding cigarette case won the Silver Award for Quality Evaluation, which is a good example.
3. Water-soluble inks for flexo printing do not contain substances that are harmful to humans, such as organic solvents and heavy metals, so they are called "green prints." Water-based inks are very important for the printing of foods, medicines, and other product packaging. Countries in Europe and America have already stipulated that packaging prints should not contain harmful substances and should not harm the person. In recent years, it has been heard that due to the fact that domestic packaging is not environmentally friendly and returning incidents. In late July of this year, Shanghai TV News reported that the Shanghai Food Quality Supervision and Administration Office tested two Shanghai food processing bags and declared that the content of each M2 toluene should not exceed 3 milligrams. The excessive packaging bags are prohibited from use. The printing plant will stop production. The use of flexo printing inks is a good way to solve such problems. The economic benefits and social benefits are also self-evident.
4. The production cost of flexographic plates is considered to be much more expensive than that of offset plates. Platemaking cost, flexographic is calculated as xx yuan/cm2, offset printing is priced according to the size of printing cylinder. When the format is large and the pattern is not large, the flexographic plate can be installed in a partially collage manner. This not only reduces the burden on the price of the plate, but also reduces the gap between offset printing and offset printing, and it also has one of the characteristics of letterpress printing. Flat printing and gravure printing cannot be operated in this way, especially when printing large-scale corrugated cardboard.
5. The flexographic printing plate has an imprint resistance of about 500,000 to 1,000,000 impressions, and an offset between 50,000 to 100,000 impressions and a debossed impression of 300 to 5 million impressions, and is suitable for various prints of large and small batch sizes.
6. The structure of the flexographic printing press is relatively simple and the width of the web can be designed with the specifications of the print product.
The narrowest width of the narrow-width machine is only 8 inches, and even narrower, suitable for label trademark printing. The widest corrugated board printing slot machine has reached more than 3.6m, which is beyond other printers. The same four-color flexo printing machine, whose price is only 30-40% of offset printing presses and gravure printing presses, greatly saves costs, and the return to investors is indeed attractive.
7. The flexographic printing plate cylinder diameter is variable, according to the size of the print product in accordance with the drum diameter of the roller drive gear, so the size of the plate cylinder diameter (also the circumference of the drum) is limited by the number of gear teeth. Changes in diameter (perimeter) are graded (variables are one-to-one variables), which can also result in a small amount of wasted paper. In recent years, with the application of the servo technology gearless transmission (by the direct drive roller of the motor), the level difference is only a variable of a pulse. Such a variable can be regarded as a stepless change in the change of the printing paper length, which is advantageous for saving printing. Materials, reduce costs. On the other hand, gearless transmission is more conducive to improving print quality.
8. In recent years, the gas-lifting sleeve printing plates are under the pressure of the flexo printing industry. The replacement of the pre-printed plate and the printing plate sleeve shortens the man-hours for flexo plate changing from 2 to 3 hours to 1 hour or less. The replacement of the sleeve not only reduces the labor intensity, but also reduces the preparation time for the job, which is to increase the printing production time, so the economic benefit is considerable.
Fourth, the lack of flexographic printing
Although flexographic printing technology is still continuously developing and improving, there are still some deficiencies, mainly including:
1. Compared with offset printing, plate printing costs are higher and the gap is larger.
2. The production of a flexographic printing plate requires multiple exposures. After washing, it must be dried for 1 to 2 hours, and the production cycle is longer. For time-sensitive newspapers and other prints, special plates must be used, such as the new digital direct plates to meet the demand.
3. Stickers require high skills and time, and increase the consumption of double-sided adhesives.
4. The anilox roller is expensive, and in order to be suitable for thick and thin printing, three or four sets of anilox rollers with different thread counts and mesh pocket capacity (BCM) must be provided, which increases the financial burden on the company.
5. The printing plate sleeve is also a big investment, and the bonding consumes auxiliary working hours when reprinting.
6. When flexo printing is used in printing dot products, the dot gain rate is relatively large, and the level of performance is in the range of 3% to 95%. The expressive force is slightly inferior to offset printing.
V. Flexo, Offset, Gravure Printing Technology Performance and Cost Comparison
Table 1 lists the technical performance and production costs of flexographic, offset, and gravure printing. It allows investors to compare flexographic production, consider comprehensively, and conduct comprehensive analysis. Since flexographic printing involves a wide range of products and many varieties, it is difficult to list specific economic numbers for some items. Enterprises can fill in the tables according to their own product types and the prices of purchased equipment materials for analysis. It is believed that the overall benefits of flexographic printing are ideal.
Six, some suggestions
1. Since flexo printing has a wide range of applications and there are many types of flexo presses, flexographic printing must be developed according to the market orientation of the company when purchasing flexographic printing.
2. When purchasing a flexographic printing press, it is necessary to select the appropriate supporting equipment according to the process requirements of the product. It is not necessary to use too much of it, and what functions are put on a machine, and most of the unused units eat up the benefits.
3. The selection of anilox rollers does not necessarily require the number of lines to be too fine. Under the premise of suitable dot printing requirements, they tend to use coarser textures. CMYK can also be used in combination, so that the service life of the anilox roller can be extended, and spare The number of anilox rolls will be reduced, saving investment and reducing costs.
4. The application of the version of the roller sleeve technology can reduce the time for down-loading plates and improve the utilization of equipment. However, the number of sleeves is not large and the manufacturing cost is high. With the expansion of use, the production price will fall. Printing production units must support the application of this new process equipment.
5. Flexographic plates are available in solid and liquid and thin and thick versions, as well as water-soluble Napp plates. Liquid plates are cheaper than solid plates. In addition to the thickness of solid plates, the price difference is very large. Under the premise of not affecting the printing quality, in order to reduce the cost, a cheap and high-quality plate can be selected.
Flexographic printing does have many advantages, but it must also be seriously studied and analyzed when it is implemented. It should conduct comprehensive and comprehensive assessments on many aspects such as technology, market, and cost, and if only one of its advantages or disadvantages is considered, it will only lead to an underground conclusion. There will often be less loss and business failure. ※
Author unit: China Printing Association flexo branch
Author: Zhang Yixiong