Postpress: A Brief Discussion on Gravure Off-machine Die-cutting

The gravure printing machine is an efficient and high-quality printing machine and is widely used in the production of packaging prints. Because of its long plate-making cycle and long service life, it is particularly suitable for printing long-line, large-volume products.

The gravure printing machine is not only suitable for plastic film packaging prints, but also suitable for the production of paper type prints. Among them, after the film type printed matter is printed and rolled into a roll, the post-synthesized bag is cut, and the cutting process is reasonable and mature. This is not discussed here. This paper only discusses the methods that should be used for post-processing processes in the gravure products of paper.

Among gravure printing products, there are quite a few varieties of packaging cartons, especially cigarette packs. Taking cigarette pack production as an example, the traditional production process is compared with the offline die cutting process to analyze its advantages and disadvantages. People in the industry discuss together.

The gravure printing machine is a production method that adopts the material feeding and non-stopping technology. After the color printing, it is taken into the form of a roll and taken off. After off-line, the roll-shaped printing product is cut off and collected by a single marking length and then collected. The single-sheet prints collected from the cuts are subjected to spine prominence, indentation, die-cutting, rejecting, collection, inspection, and packaging. If the prints require hot stamping or laser-targeted hot lapping, additional processes are required. The large area, the use of many machines, many personnel, and sometimes off-line operation of the roll printing material in the cross-cut process interrupted Zhang accuracy exceeds the standard, but also requires a large number of inspection personnel and a large area of ​​work space. Because the Zhang Zhang is to serve the next process, each print must be at least 15mm in length, which directly results in the loss of the paper and increases the production cost. If hot stamping, indentation and die cutting are required, at least On the machine twice, the material will be deformed due to changes in air temperature and humidity during the turnover of the workshop, resulting in an increase in scrap rate. The above conditions are relatively clear to the industry. Since all factories use the same kind of technology, everyone is on the same starting line in competition, and there is no competitive pressure brought by new methods and high efficiency.

The traditional process flow will inevitably change with the development of industrial technology. The first is to change the traditional gravure rewinding method to continuous machine breaking, because of the low cost of the machine-breaking structure and the elimination of offline crosscutting machines. Process. Since the tension and breaking tension are on the same tension stage when the machine is broken, the accuracy of the cutting is also more accurate than the off-line breaking. Therefore, it is widely used in many gravure box production lines. The bronzing and spine process, indentation, and die-cutting processes have to adopt the traditional method, and obvious technical progress has taken place with this method. In order to solve the existing problems, there are also a small number of imported machinery manufacturers that use a machine for indentation, die-cutting, and collection processes. Although technology is now available, there are many drawbacks. The analysis is as follows:

Since the gravure printing machine works at a high speed without stopping, the traditional paper-splicing method is a method of fast splicing of the tape, and the joint is about dozens of centimeters in length as a double-layered printing material. The gravure printing group is a rubber roller because the embossing roller is a roller. A slight amount of vibration can still pass, but when it enters the indentation and die-cutting station, it will greatly impact the indentation on the roll and the die-cutting roll, reducing its life, and at the same time passing through the high-speed reject rejection and When the finished product is collected, irregular joints will cause collection failures on the collecting table. If the collecting table fails, the entire gravure line will be shut down. When the connecting operation is performed on the gravure printing machine, the unwinding mechanism must be designed. For butt joints, good working conditions can be ensured. This will make the gravure rewinding mechanism bulky and increase the cost, because the docking paper is carried out at zero speed, it is necessary to design the storage rack, joint strength and tension It is difficult to control, the success rate of joints is not very high, and the cost of the system is high. The products imported by France are more than RMB 2 million.

In addition, there is a technically difficult problem. The gravure printing machine suddenly stops before printing and gravure printing. If the printing process is shut down, the gravure printing group must be pressure-controlled for dampening. When printing is started and the material in the die-cutting station is to be kept from being fed between stations, a clutch must be used to separate the gravure from the post-processing section. It is also necessary to make the gravure printing station to perform the pressure-compression operation before the second time when it is put into production before the memory is stored in the original phase, so that it will not be re-inserted, and the printing and die-cutting positions will be misaligned, the mechanism will be complicated, and the operation will be difficult. In addition, because of the high cost and the complexity of the system, the accuracy of the position is affected. We believe that the above method is not desirable, and in fact there are no successful examples. Maybe you would think that this view is arbitrary and can be solved without a shaftless drive? Yes! If each printing unit and each post-processing unit are using AC servo shaftless transmission, there is no problem described above. We don't talk about how expensive it is to use this system. We also need to consider the reliability of the entire electrical system because the system's printing manufacturers cannot be equipped with maintenance personnel. Even so, we have to analyze the value is not worth doing, because the printing process needs to be consistent in speed, temperature, ink viscosity and non-stop production conditions to ensure the consistency of the ink, get high quality prints and get high In the finished product rate, when working in each color group, the operator needs to monitor the working status of each color group to ensure that it can not stop due to failure. Afterwards, the processing procedure is to perform bronzing (including cold foil stamping) on ​​the printed image. Spurs, indentations, and die cutting are allowed when the above operations are performed. The shutdown will not result in a decrease in quality and an increase in waste products. The basic requirements for printing operations and post-processing operations are different, and it is contradictory to combine the production of two different types of process operations. When the post-processing process is bronzing, it is impossible to design a non-stop system when the film roll is exhausted, and the film roll must be shut down. Once the failure of the finished product collection and waste rejection must be stopped to eliminate the failure, such as the continuous production will inevitably affect the printing quality and yield, in a Once the multi-color printing press is turned off, the pressure is turned back on and the waste is conceivable.

From the above analysis, I believe that it is not wise to print the roll print printed on the gravure printing machine. It is not necessary to perform the cut-off. Instead, it takes the roll off-line and then goes on the machine. It is advisable to connect the line after the next process that needs to be processed. select. Firstly, after the roll print is uncoiled and pre-positioned by tension and position control, re-printing and repositioning of the bronzing (including cold-ironing) double-positioning can be performed for the laser mark positioning hot, and then the spine, the creasing, the rejecting, and the finished product collection operations are performed. The whole operation process is continuous and in one go. Therefore, this revolutionary change completed in the post-sequence process can reduce the number of printers in printing companies, save printed materials, reduce personnel, reduce the area of ​​factory buildings, increase the yield of finished products, and reduce energy consumption. In short, there are many advantages and the prospects are lure. people. At the same time, fierce competition in the market forces you and me to make such a choice.

The reason for the above realization is very clear. The possibility is beyond doubt. It is equivalent to the fact that there is a cross-cutting machine that knows how to cut the sheet, but now it only expands the function of the standard cross-cutting machine and increases the number of other stations. Integrated operation.