What is the development direction of the sleeve in flexo printing?

(Sleeve in flexography—wher to next?) This article describes the operation and economic efficiency of a flexo sleeve. Sockets with Adhesive Patch Tape Recently, Rotec introduced the new sleeve system to the market, the Tacky Light Sleeve, which combines the advantages of a compressible sleeve with a sticky adhesive tape on the surface. There are three different types. The compressible layer. After special treatment, the surface is self-adhesive and can be reused continuously, and the service life of the surface can be guaranteed for one year. Although the Tacky Light sleeve is more expensive than the conventional sleeve, since there is no need to add additional tape, the sleeve needs to be replaced only after replacing 15 plates. If the plate often needs to be replaced and there is no need to store the installed sleeve, then Using the Tack Light sleeve is still a good deal. It is worth noting how much money is spent on installing tape every year. Eliminating this process not only reduces costs, but also avoids errors caused by loading and unloading adhesive tape. Unlike traditional mounting tapes, self-adhesive adhesive tapes do not affect their tack strength after being used 8 to 10 times. This will make correction easier when installing the plate. The length and perimeter of the sleeve must be understood when the sleeve is used to cover the printing steps. The principle is that medium and wide web printing presses (1000-1600mm) are not recommended when sleeve printing covers a length less than 300mm. There is no problem when the print coverage length is 350mm or more. In addition, for a duplex product (eg, 540mm in duplex length, rather than a 270mm print length), it is more suitable for sleeves and can be used for high speed printing, but it is not often used due to the high cost of printing plates it requires. . Wide web widths and short print coverage can reduce the speed of even the most advanced printers. The best choice is to use a support shaft to cover sleeves with a plate range of about 150 mm. At this time, the printing length of 300-440mm can use the same supporting shaft, while 450-590mm uses a longer supporting shaft, and so on until the printing length is between 1250-1600mm. From the printing length of 1050mm, the supporting shaft with the shaft's outer diameter of 330mm can be used. At this time, the width and printing speed of the web are the most important constraints. When there are many kinds of supporting shafts of different circumferences, the supporting axis of the smallest circumference is taken as the starting point of the required printing length, while the supporting shaft provides printing steps of 150 mm. Replacement of sleeves on the press An important question here is: Is the sleeve replaced on the press or under the press? Unfortunately, it is not possible to come up with a general or exact answer now, because the print width, the step length and the structure of the press are all important factors. A CI press with a web width of 900-1000mm can be on the press sleeve without any problems. However, maybe someone has to ask whether it is really meaningful to replace the sleeve on the press? Is it necessary to have a roller crane assisted by the printing press? To answer this question, the following points must be noted: the height of the press, the length of the print image, the number of color groups, and the maximum print speed, which are related to the diameter of the center impression cylinder. Increasing the length of the printed image and the number of printing steps, changing the printing ink (water-based or solution-based) and increasing the printing speed inevitably increase the diameter of the central impression cylinder. Although this would make it easier to access the printed panel, it would increase the height of the press so that an automatic system had to be used to lift the sleeve from the press and transfer it to the drum crane to complete the sleeve replacement. A sleeve with a web width of 1000 to 1200 mm is more suitable and quicker to replace outside the machine. This also applies to the case where the step length is greater than 1100 mm, when the diameter of the sleeve reaches 300 mm. Obviously, sleeves with a cylinder width of 1200 mm and a diameter of 350 mm are more suitable for on-line replacement because they are only 1 meter high. Also, don't forget to replace the sleeve while the support shaft needs to be replaced, but it does not require a longer standby time because the replacement new sleeve is already mounted on the support shaft. The sleeve-over-sleeve method This technology has a number of corresponding relationships with digitally driven CI printers. This type of printer usually has a fixed bearing shaft that can be used for a minimum printing step size. Thick-walled or adapter sleeves are used for sleeves with longer printing steps. For high-quality printing, converter sleeves are the best solution. A fixed bearing shaft is necessary because the direct drive must have a solid connection to the driven shaft. This shaft is mounted in the motor or in the electronic reduction gear, so that the interchangeable shaft requires a more complicated clutch because even the smallest backlash between the motor and the shaft affects the registration process during printing. The fixed bearing shaft has good ergonomics and is inexpensive and does not require an extra shaft. However, it must be remembered that increasing wall thickness and printing width will lead to an increase in the cost of the sleeve. Storing Installed Sockets For any discussion of the use of sleeves, everyone asks a question: If you need to reprint, do you want to store the sleeve? Or remove the plate? The answer to this question is the simple digital management of some factors: Number of printing step reprints Number of reprints per printing step Number of reprints Time interval How much storage space is needed Time of loading and unloading Staff needs Experience tells us that the printing factory The order structure consists of prints that are reprinted "often" and "occasionally." Therefore, it is very reasonable to store only the sleeves that often need to be reprinted and to remove other sleeves. Tacky Light sleeves work well at this point. If you often print the same print layout with a small number of print jobs, you can use two sleeves to solve the problem. One for production and the other for preparation for the next print. If you store a cartridge with a printing plate, the most important thing is to store it vertically or place it in a room that is as dark as possible, ventilated, and has no major temperature difference. High-quality sticky adhesive tape should also be used to make the plate firmly adhere to the sleeve. If you use a compressible sleeve, the situation will get worse. Larger temperature changes can deform the material (such as adhesive tape, plates, and sleeves) and cannot guarantee accurate reprints. Unsatisfactory storage conditions, improper installation, expansion or contraction of the printing plate, and drying of the sticker tape can cause many problems, such as incomplete ink placement or overprinting. If you try to increase the pressure on the press to solve this problem, you may need to re-install or make a new printing plate. Adhesive tapes change properties during the printing and storage of compressible sleeves, and the thickness of adhesive tape is only 0.01 mm. On the other hand, some sticky tapes show good stickiness on the smooth surface of the hard sleeve, while non-compressive sleeves require foam sticky tape. Sleeve plate making work In order to make a printing plate sleeve, it is necessary to coat the polymer material on the sleeve and then expose and clean it in the circumferential direction. Usually the plate is exposed by the platform, washed and mounted on the sleeve. The plate production on the sleeve uses CTP technology to eliminate the issue of plate loading and unloading. Direct digital drive can achieve accurate print steps. Selecting the plate and web surface speed reduces or increases the image length by 2%. The printed image becomes longer when the speed of the web is faster than the speed of the plate, and vice versa. These corrections are not even noticeable even in the best line art and four-color halftone activities. A magnifying glass can be used to observe the elongation or deformation of halftone dots. Rotec's hard surface sleeves and compressible sleeves are suitable for overall imaging because of their materials' resistance to UV light and cleaning agents. The accuracy of the sleeve sometimes raises the question: Is the accuracy of the plate cylinder higher than that of the sleeve? This question is related to print quality, and the answer is obvious: No. In principle, the plate cylinder has the same characteristics as the hard surface sleeve. With a compressible sleeve, the print quality can be improved. Although this sleeve has a larger tolerance than the roller, there is no significant effect on the quality - at least taking into account the tolerances on the printing plate and the press will not have a significant impact. Improvements to reduce sleeve tolerances are still in progress. Anilox roller sleeves General sleeves are much less handled than rollers because they are slightly heavier. It is often seen that the anilox roll is heavily dropped to the ground. Customers often hesitate to use sleeves or rollers. The 1000mm sleeve suitable for printing does not have any problems with replacement and ink supply characteristics. It is not recommended to use UV inks on them because the temperature of the sleeve, like the insulator, cannot be increased to a sufficiently high level, and the temperature at which the UV ink is optimal is 30 to 32°C. It is difficult to use anilox roller sleeves when the web width exceeds 1000mm, because they are difficult to operate, although in theory they can be used for 1400mm web widths, they are no longer used in practice. The diameter of the barrel becomes critical. Manufacturers of sleeves are clearly aware of the difficulty in ensuring the accuracy and tolerances of anilox and engraving rollers. Manufacturing tolerances for anilox roller sleeves with a width of more than 1200 mm can result in very low print quality, especially in demanding fine halftone print jobs. Due to the length of the sleeve, it may cause some damage to the printing press. Anilox rollers are often not replaced as often as printing plate sleeves and are economically different. The well-treated anilox roller sleeve is generally recoated two to three times. Is the sleeve economical? If there are a large number of printing lengths that are relatively short, and the sleeves have a short step length of print jobs or require a variety of different anilox rollers, then the use of sleeves will bring good results. At this time, if the already installed version of the sleeve is stored and its lifespan is almost infinite, then the sleeve is undoubtedly very cost-effective. For compressible sleeves, the most important thing is to keep them clean. Dry inks, dust, and solvents cannot stay on the surface, otherwise they can penetrate into the inner layer to break the compressibility. Cleaning with the right cleaner is simple. Other sleeves can be mounted on the Rotec support shaft, and they also make sleeves that fit the other support shafts. All sleeve manufacturers are pursuing tight tolerances. Loose mounting sleeves or low-precision support shafts are terrible for every printer. Therefore, it should not save money in the wrong place.