Research and Countermeasures on the fuzzing of pet

2022-07-30
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Research and Countermeasures on pet paper die cutting fuzzing

cigarette packs often have the phenomenon that the cutting edge of die-cutting products is not smooth and fuzzing, especially for products printed with PET film paper, the fuzzing is more serious at the cutting edge close to the indentation line. Among the series of trademark products produced by our company, the trademark produced with pet paper has such a quality problem, which is also a common problem in many packaging and printing industries. In the past, in order to ensure product quality, the general treatment method was to brush the trademark in the inspection process. Recently, we have made an in-depth analysis of this problem. We will discuss it from two aspects: cause analysis and solution plan

I. cause analysis

1 The influence of paper properties on die-cutting fuzzing

pet film is very suitable for the development and application of general high-end brands due to its high surface gloss and flatness, strong folding resistance, good packaging and molding, and has strong anti-interference ability. However, due to the extremely strong toughness and tear resistance of PET film, the product is prone to die-cutting, fuzzing and other quality problems in the post-processing die-cutting process. The usual solution is to increase the die-cutting pressure in the actual processing operation process, which has a certain impact on the service life of the die-cutting knife, so it can not achieve the goal of permanent cure. In contrast, the material of OPP film composite paper is thinner and less ductile than PET film, and the fuzzing phenomenon in die cutting is much less. If the vacuum aluminized transfer silver paperboard is replaced, this problem can be fundamentally solved. Therefore, we can judge that PET film paper is the objective cause of die cutting fuzzing

2. The influence of die cutting operation on die cutting fuzzing

the implementation of correct and standardized equipment operation steps is an effective means to alleviate the above problems. Although paper is the objective cause of die-cutting fuzzing, the different operating levels of operators are also the main cause of unstable quality. For example, improper operation or excessive pressure will cause the blade to collide with the steel base plate too violently, directly damaging the blade of the die-cutting knife. Continuous high pressure and frequent version change after formal production are also subjective causes of blade damage. If the die-cutting knife is not detected or replaced in time, the product may have paper dust and burrs to varying degrees. This puts forward higher requirements for the proficiency, skills and experience of operators. Therefore, a skilled operator should not only understand the indentation effect, but also know the mechanical pressure required by different paper materials

3. The influence of die-cutting plate material on die-cutting fuzzing standard die-cutting plate material selection and installation is an effective method to improve die-cutting quality and reduce cutting thread. First of all, high-quality die-cutting knives should be selected. In the general high-grade die-cutting blade, with a magnifying glass, you can also find many defects, the blade is not straight and smooth. The surface of some die-cutting knives is very sharp, but the rigidity is poor. After a short time of use, the blade will be worn, which will cause fuzzing at the die-cutting place of the paper edge and rough edges. In addition, some die-cutting fuzzing is caused by improper installation of die-cutting knife and sponge strip. The sponge strip should have enough hardness to compress the paper, so that the die-cutting knife can smoothly cut the paper. Sincerely welcome the majority of users to visit our factory for guidance. Sponge strips with different hardness shall be used for different papers, and the position and height shall also be paid attention to, otherwise the due effect cannot be achieved. Therefore, the selection, collocation of these materials and the setting of process parameters have a direct impact on the die-cutting effect

through the analysis and summary of the above three aspects, it can be seen that if we want to fundamentally solve the problem of die cutting fuzzing, we can only replace the paper with aluminized paper, which can meet the requirements of "green environmental protection" and "clean production" of tobacco factories. However, the performance of aluminized paper is slightly worse than that of PET film in terms of surface gloss, flatness, folding resistance and packaging molding, which is bound to have an impact on the printability and packaging effect on the machine, which is specifically reflected in the brightness, folding resistance, rubbing resistance and many other aspects of the product ink. Therefore, at present, only from the standard operation, adjust the process route, and select the appropriate die-cutting materials to improve it, so as to reduce or mitigate the occurrence of this problem

II. Solution plan

1 Operation specification

according to the particularity of paper die-cutting fuzzing, we draw up the following operation steps for your reference and implementation

① plate loading: when a new blade plate is put into the machine, the pressure test shall be carried out first. The pressure during commissioning must be light. The product shall not be tested until the surface plate is printed. The pressure during commissioning shall be subject to clear marks on the paper

② pressure test die cutting: pad paper under the steel plate for large-area pressing. The paper should be thinner than 90 g/m2 coated paper. After pressure test, observe whether the printed matter at the knife edge is easy to separate. The ideal pressure is that the paper edge of each notch is just separated. At this time, the pressure of the machine is the minimum and the pressure is the most appropriate. The die-cutting edge is smooth, lint free, easy to separate, and the die-cutting knife is not easy to wear. When the die-cutting machine starts to adjust the pressure, it should first be adjusted to about 20%, and then according to different positions, local paper padding is carried out to balance the pressure, and then the pressure is locked for formal die-cutting

③ alignment pressure: partially pad the uncut part to make the pressure of each die cutter of the layout uniform, and then gradually increase the pressure of the machine

④ formal die cutting: lock the pressure, control the speed at 4500 sheets/hour, and the pressure is about 42 tons. In the process of die cutting, the overall blade will become blunt, and individual blades will have gaps or fall off at the olecranon. At this time, the operator is required to be diligent in changing the blade. When changing a knife, we should also consider that the blade of the new knife is usually higher than that of the old one. In this way, not only the die-cutting effect is good, but also the production speed is fast and the production efficiency is high

2. The selection and installation of die-cutting material

die-cutting knife and sponge strip is also one of the reasons that affect the quality of die-cutting. Different paper should use different die-cutting knives and sponge strips. The reason for the fuzzing of paper die cutting is that the paper is torn off by mechanical tension after the die-cutting knife becomes blunt. Therefore, sponge strips and die-cutting knives with strong hardness can be selected. The sponge strips can clamp the paper and slow down the effect of trace lines on the paper tension

when selecting a high-quality die-cutting knife, attention should be paid to selecting a high peak knife or a low peak knife according to the thickness of the die-cutting material that can be used as a myocardial patch to effectively treat the rat model of myocardial infarction, and pay attention to the transverse or straight line treatment of the knife peak. The knife with cross grain treatment has better effect on die-cutting paper, is more durable, has higher stability and precision, and is not easy to crack after bending. Therefore, the manufacturers of long-term die-cutting cigarette cases, but the second step is not good, so they choose the low peak cross grain die-cutting knife. Because the stiffness of the low peak knife peak is higher than that of the peak, it is more stable under pressure and more durable

3. Process adjustment

in order to reduce the influence of frame lines and trace lines on die-cutting quality, the die-cutting effect should be further improved. The processing technology can be adjusted from the original pressing frame, indentation and die cutting to pressing frame first and then indentation and die cutting, and special steel template (without pressing frame) can be prepared. 60 ° solid sponge strips shall be selected for all sponge strips, and a special plane can also be arranged to take charge of the die cutting of products with serious fuzzing. That is, after checking the equipment status, designate a die-cutting equipment with high precision and flat pressure to die-cut the product. This can not only reduce the number of version changes, reduce the fuzzing problem caused by the damage of the die-cutting knife caused by version change and debugging, but also lay a foundation for the stability of the quality of batch products. In addition, excellent die-cutting captains with rich experience and excellent technology can be selected from the die-cutting captains to take the post. This will not only enable operators to explore and accumulate more experience on a relatively single brand, help to find problems and solve them in time, but also provide technical support for improving product quality. The so-called special edition is to use the above steel template to replace the log template. Because the steel template has no bottom film, the stress deformation of the paper during the die-cutting process is much smaller, so the fuzzing of the paper will also be reduced

in addition, with the improvement of the plate making process, the flat tension die-cutting machine can follow the roll to roll die-cutting process in the die-cutting mode, first creasing and then die-cutting, so that the paper will be subject to fewer constraints in the die-cutting process, and the paper will be die-cut completely in the plane state. Theoretically, there will be no traction force of the creasing line on the paper, and the paper will not be torn off

through the implementation of the above improvement scheme, the fuzzing condition of paper die cutting will be effectively controlled and improved. With the acceleration of the national promotion of environmentally friendly paper, the improvement of die-cutting materials in plate making plants, and the continuous updating of die-cutting technology and equipment, the common problems of unsmooth and fuzzing of cigarette packs after die-cutting will be overcome. ※

Ou Liguo Author: Hunan Changde Jinpeng Gravure Printing Co., Ltd.

source: printing magazine

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