The development direction of sleeve in flexo print

2022-07-30
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Development direction of sleeve in flexo printing (Part 1)

sleeve with adhesive plate adhesive tape

recently, rotec introduced a new sleeve system to the market - tacky light sleeve, which combines the advantages of compressible sleeve, has adhesive plate adhesive tape on the surface and three different types of compressible layers

the surface is self-adhesive after special treatment, which can be reused continuously, and the service life of the surface can be guaranteed to be as long as one year. Although the tacky light sleeve is more expensive than the traditional sleeve, because there is no need to add additional tape, the sleeve needs to be replaced only once after replacing the printing plate 15 times. If the printing plate needs to be replaced frequently and the installed sleeve does not need to be stored, it is more cost-effective to use the tacky light sleeve

it is worth noting how much money is spent on the installation of adhesive tape every year. Saving this process not only reduces the cost, but also avoids the errors caused by the handling of adhesive tape

different from the traditional installation tape, the self-made adhesive plate adhesive tape does not affect its adhesive strength after 8~10 times of use. This makes it easier to correct when installing the plate

length and perimeter

when using the sleeve, the printing step that the support shaft can cover must be clear. The principle is that when the sleeve printing coverage length used is less than 300mm, it is recommended not to use medium-sized and wide web printing machines (mm)

there is no problem when the printing coverage length is 350mm or more. In addition, for duplex products (for example, the duplex length is 540mm, instead of a printing coverage length of 270mm), it is more suitable to use the sleeve and can carry out high-speed printing, but it is not often used because of the high printing plate cost

generally, the wide web width and short printing coverage will reduce the speed of even the most advanced printing machine. It is better to use the supporting shaft to cover the sleeve with the printing plate range of about 150mm. At this time, the same supporting shaft can be used for the printing length of 300~440mm, while a longer supporting shaft can be used for 450~590mm, and so on until the printing length is 1250~1600mm

the support shaft with an outer diameter of 330mm can be used from the printing length of 1050mm. At this time, the width of the web and the printing speed are the main constraints. When there are many kinds of support shafts with different perimeter, take the support shaft with the minimum perimeter as the starting point of the required printing length. At the same time, if the support shaft provides 150 and then pulls m at 200 ℃, its use value will be greatly reduced by the printing step of M

replacement of the sleeve on the printing press

an important question here is: whether to replace the sleeve on or under the printing press? Unfortunately, it is not possible to get a general or exact answer now, because the printing width, step length and the structure of the printing machine are all important factors. A CI printer with web width of 900~1000mm can sleeve on the printer without any problem. However, some people may ask, does it really make sense to replace the sleeve on the printing press? Whether a roller crane is required to assist the printer. To answer this question, we must pay attention to the following points: the height of the press, the length of the printed image, the number of color decks and the maximum printing speed, which are related to the diameter of the central 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 will inevitably increase the diameter of the central impression cylinder. Although this will make it easier to access the printing panel, it will increase the height of the printer, so that an automatic system has to be used to lift the sleeve from the printer and transfer it to the roller crane to complete the sleeve replacement. The sleeve with a web width of 1000~1200mm looks more suitable for replacement outside the machine. The frequency is 80 ⑵ the preferred combination with a short test time of 50Hz is also faster. This is also applicable to the case that the step length is greater than 1100mm. At this time, the diameter of the sleeve reaches 3, and the elongation at break of ordinary polymer materials is mostly between 50% and 100%

obviously, sleeves with a width of 1200mm and a diameter of 350mm are more suitable for on-line replacement because they are only 1m high. In addition, please do not forget that the support shaft also needs to be replaced when the sleeve is replaced, but it does not need a longer standby time, because the new sleeve has been installed on the support shaft

the sleeve over sleeve method

this technology has many corresponding relationships with the digital driven CI printing press. This type of press usually has a fixed bearing shaft, which can be applied to the minimum printing step. Thick wall or adapter sleeves shall be used for sleeves with long printing steps. For high quality printing, the converter sleeve is the best solution

it is necessary to fix the bearing shaft, because the direct drive must be firmly connected with the driven shaft. This shaft is installed in the motor or in the electronic reduction gear, so the exchangeable shaft requires a clutch with a more complex structure, because even the smallest back impact between the motor and the shaft will affect the registration changes in the printing process

the fixed bearing shaft has good man-machine operability and is cheap. No additional shaft is required. However, it must be remembered that increasing the thickness of the wall panel and the printing width will lead to an increase in the sleeve cost

storing installed sleeves

in any discussion about using sleeves, everyone will ask a question: if reprinting is required, do you want to store the sleeves? Or remove the printing plate? The answer to this question is simple digital management of some factors:

printing step length

number of reprints

number of reprints per printing step length

time interval

how much storage space is required

time required for loading and unloading

personnel requirements

experience tells us that the order structure in the printing plant is composed of "frequent" and "occasional" reprints. Therefore, it is very reasonable to store only the sleeves that often need to be reprinted and disassemble other sleeves. The tacky light sleeve works well at this point

if the same printing layout is often printed but the printing number is small, two sleeves can be used to solve the problem. That is, one is used for production and the other is used to prepare the next printing

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