With the development of society and the continuous improvement of people's living standards, when purchasing goods, consumers not only require the inherent quality of the goods, but also put forward higher requirements for the packaging of the goods. This includes not only the design requirements for the packaging and decoration of commodities, but also the quality requirements for the post-press processing of the packaging.
Die cutting and indentation processing technology is suitable for surface processing of various types of printed materials. Especially the surface finishing of various grades of cartons, cartons, trademarks, artworks, etc. is also one of the important means to achieve packaging design. The die-cutting and indentation process not only plays an important role in the final quality and effect of packaging, but also can greatly improve the artistic effect of the printed matter, and it also gives new features to the printed matter, which has become an important means of value-added and promotional printing. Therefore, the die-cutting and creasing technology is more and more popular, and the range of use is becoming wider and wider. However, in the die-cutting and indentation process, a series of problems often occur, which affect the smooth progress of production. Therefore, this article takes the common problems in the production of die-cutting and indentation of horizontal flat-press die-cutting machines as examples for analysis , I hope to help the actual production.
The principle of automatic horizontal flat die-cutting die-cutting machine is similar to that of offset printing machine. The faults between them are not analyzed here. Only the common problems of die-cutting part are discussed below.
Uneven pressure
The pressure is not uniform during the die-cutting indentation process. There are generally two cases:
1. If the pressure is slightly uneven, it may be due to the uneven distribution of the die-cutting knife and wire (steel knife, steel wire), which causes the dynamic platform to be skewed during die-cutting. Equipped with a balanced knife line to make the platform evenly stressed.
2. If there are serious pressure unevenness at the front and back of the platform, it is mainly caused by the inconsistent height of the four connecting rod swing rods supporting the moving platform. Wear, it needs to be replaced if the wear is serious, otherwise it is necessary to adjust four pressure adjustment irons until the pressure is consistent.
Die cutting accuracy is not high
The accuracy of die cutting is one of the most important standards for measuring the quality of die cutting, and it is an important guarantee for producing qualified products. In the actual production process, it is often the case that the accuracy of die cutting does not meet the design requirements. There are many factors that affect the accuracy of die cutting, mainly in the following aspects:
1. The main drive chain is worn and elongated, which will directly affect the positioning accuracy before die cutting. At this time, only the chain can be replaced.
2. The intermittent mechanism is worn, causing the tooth row to shake during the stop or start process, thereby affecting the die cutting accuracy. In this case, it generally only affects the positioning accuracy. In this case, the intermittent mechanism should be repaired.
3. The positioning distance of the front and rear positioning pendulum is too small. Because the length of the chain itself has a certain error, if the positioning distance is too small, the chain error cannot be eliminated during front and rear positioning, which affects the die cutting accuracy. At this time, the adjustment screw of the front positioning swing frame or the cam position of the rear positioning swing frame should be adjusted so that the front and rear positioning frames can move the row of teeth by a distance of 2 to 3 mm.
4. The positioning of the upper die cutting plate or the lower die cutting plate is inaccurate. Long-term use of the machine will cause the positioning block on the die-cutting plate frame or die-cutting base plate to wear out, which will cause the fit gap to be too large and cause the die-cutting precision to decrease. At this time, the positioning block should be replaced.
5. The wear of the side positioning plate is an important factor that causes inaccurate side positioning. Since the amount of positioning toggle is not enough to compensate for the amount of wear, it will cause the side positioning accuracy to deteriorate. At this time, the side positioning plate should be replaced.
6. The pressure of the gripper is too low or uneven. If the elasticity of the movable teeth of the gripper becomes smaller due to long-term use, it will cause the paper to slip or fall off during the transfer process, which directly affects the accuracy of die cutting; uneven pressure between the grippers may cause the paper to die cut Skew in the process. The movable teeth should be replaced at this time. In addition, the fixed teeth should also be consistent in level, otherwise there may be paper collision when the paper is gripped or the paper is wrinkled after gripping the paper, which affects the accuracy of die cutting.
7. The cardboard is deformed or stretched during the operation, resulting in inaccurate "overprinting", which affects the accuracy of die cutting. Appropriate paper should be selected to reduce the impact of material defects on the accuracy of die cutting.
8. The operator's operation error caused insufficient precision, or the die-cutting precision did not meet the requirements due to the low precision of the die-cut version. At this time, operators should be professionally trained, improve production management requirements, or remake die-cut plates.
Die-cut loose version
The so-called loose version refers to the phenomenon that the waste edge and the cardboard are scattered during die cutting and the paper is not smooth. When the loose version is serious, it will affect the normal production. The main reason for the loose version is the mistakes in the die-cutting plate-making process and the improper selection of elastic strips (or sponges); at the same time, other factors may also cause the loose version.
1. When making a die-cutting plate, if the shapes of the live parts are complex or there are many live parts, and the connecting points of the die-cutting are small and few, it is easy to cause loose plates during die-cutting. At this time, the number of connecting points should be appropriately increased, and if possible, the length direction of the work should be consistent with the paper conveying direction.
2. If the elastic strip (or sponge) on the die-cut plate is too soft, the paper cannot be bounced up smoothly, and it will also cause loose plates. At this time, high-quality elastic rubber strips (or sponges) with high hardness and good elasticity should be selected.
3. Too early start of pressure discharge is also an important reason for the release. After die cutting, when the moving platform is lowered, although the paper has been ejected away from the knife line by the elastic strip (sponge), because the elastic strip (sponge) is generally 2 to 3 mm higher than the knife line, if the grippers are When it starts to move, the elastic tape (sponge) still presses the paper against the die-cutting bottom plate, which easily tears the paper and causes loose printing. At this time, the coupling sleeve of the intermittent mechanism and the main sprocket shaft should be loosened to adjust, so that the moving platform descends from 7 to 8 mm from the top dead center (when the corrugated paper is die-cut, it should be about 10 to 15 mm), and the pressure row starts to move.
4. In addition, the quality of the die-cut printed matter is also one of the reasons for the loose version. If the paper quality of the print is too poor and the fiber is too short, it may appear loose in the die cutting process. At this time, you can reduce the die cutting speed and increase the number of connecting points appropriately.
The cutting edge is not smooth during die cutting, even fluffing
The main reason for this phenomenon is related to the quality of the steel knife and whether the role of the steel knife can be played normally. There are mainly the following situations, which must be paid enough attention to.
1. The poor quality of the steel knife, the unsharp edge of the blade, and the poor adaptability of the die cutting are the important reasons that cause the blade to be unsmooth or even fluff. According to the different performance of the die-cut printed matter, high-quality steel knives should be selected to improve their die-cutting suitability. If there are no special requirements, try to use steel knives with horizontal grain treatment.
2. The blade of the steel knife is seriously worn, and it is not replaced in time, so that the steel knife cannot function normally. The wear of the blade of the steel knife should be checked frequently, and if the wear is severe enough to affect the quality of the die cutting, a new steel knife should be replaced in time.
3. When the die-cutting pressure is adjusted, the paper pad at the steel knife is not handled properly, that is, the pressure compensation is not done well, which causes the die-cutting pressure to be uncomfortable, and the edge of the blade is not smooth or fluffy. The die-cutting pressure should be readjusted and the pad paper replaced to make the pressure meet the die-cutting requirements.
4. The matching and installation of die-cutting knife and elastic rubber strip (or sponge) are out of specification, which will also cause the above phenomenon. The elastic strip (or sponge) must have sufficient hardness to press the paper, so that the die cutter can cut the printed matter smoothly. Different paper should use elastic strips (or sponges) of different hardness. At the same time, the placement and The height must also meet the specifications.
5. The occurrence of unsmooth edge or fluff is also related to the flatness of the bottom steel plate and the pressure of the machine. The bottom steel plate must be flat, and the bottom steel plate should be replaced if necessary.
Line burst (color burst)
Blasting refers to the cracking of the paper at the indentation when the product is die-cut or when the finished product is folded. This is a problem that often occurs in die cutting, especially when the weather is dry. It should be analyzed according to specific conditions:
1. The paper is brittle and has low water content, especially the paper polished at high temperature, which may explode when die cutting. At this time, adjust the humidity of the paper before die cutting. You can use a water machine to pass water to the back of the paper to increase its water content and make the grade slightly flexible. If the thread bursts when the box is stuck after die cutting, you can wipe the water at the crease to relieve the thread burst.
2. The surface of the printed matter has a large area of ​​blue or black and other dark colors on the ground, which is easy to explode and burst after die cutting. No or less ink additives are added to the dark ink during printing to enhance the adhesion of the ink on the paper and reduce the phenomenon of color burst and line burst.
3. When the thickness of the paper (board) is too large, it is easy to produce a burst line. At this time, the height of the die-cut steel wire should be selected reasonably.
4. The explosive line after the steel plate underlays paper, at this time the paper should be thinned.
5. When the pressure of the die-cutting machine is too large, the line will explode. At this time, the pressure should be reduced to make the waste edge just separate.
6. The indentation mold or the bottom touch paper is too thick, the indentation is narrow, and the line is explosive. An indentation die of appropriate thickness should be selected, and the indentation width should be moderate.
7. The paper powder falling from the incision accumulates in the groove of the explosive line. The operator should promptly remove clean paper, foreign objects, etc.
Irregular indentation line
The main reason for the irregularity of the indentation line is that the indentation groove on the steel wire pad paper is too wide, and the position of the cardboard is not fixed; the thickness of the steel wire pad paper is not enough, the groove angle is irregular, and there are extra rounded corners; The tightness of the row knife and fixed knife is not suitable, the steel money is too tight, and the bottom cannot be in ideal contact with the plane of the pressure plate, and it is easy to twist when the indentation; The exclusion method is to replace the steel wire pad paper, the width of the indentation groove is appropriate; increase the thickness of the steel wire pad paper, trim the groove angle; the tightness should be suitable when the knife is fixed.
When the sticker is die-cut and cleaned, the label is stuck off
After die-cutting the adhesive, the label is often peeled off by the scrap of paper during the waste removal process, especially for small-area labels, the phenomenon is more serious. Generally, this problem can be solved from the following aspects:
1. When designing, increase the label area appropriately, the shape should not be too complicated, and arrange the labels reasonably.
2. Prevent the viscosity of self-adhesive tissue paper from decreasing. Can reduce the temperature of storage and printing workshop, or increase its viscosity.
3. Replace the blunt blade, or remake the die-cut version.
4. Adjust the pressure of the die-cutting plate by the method of lower die-cutting the bottom plate, so that the pressure of the die-cutting plate is uniform, and the depth of the die-cutting indentation is consistent.
5. Accelerate the speed of die cutting and waste disposal.
The problems discussed above are some common problems in production. In actual production, there will be many other problems. You can analyze them according to the specific situation, find out the possible causes, and take corresponding measures to solve them. Only by constantly summarizing and mastering various skills in actual production and operation, familiar with the performance of production equipment, and mastering the requirements of production technology can we promptly and correctly eliminate various problems that occur in production and produce high quality for smooth production. The die-cutting and pressure wave products create favorable conditions.
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