Common problems and countermeasures in the die-cutting and creasing process

With the development of society and the continuous improvement of people's living standards, when consumers purchase goods, in addition to the inherent quality of the goods, In addition to quality, higher requirements are also put forward for the packaging of goods. This includes both requirements for product packaging and decoration design, as well as requirements for packaging post-printing processing quality.

Die cutting and creasing processing technology is suitable for surface processing of various types of printed matter. Especially the surface finishing and processing of various grades of cartons, cartons, trademarks, artworks, etc. is also one of the important means to realize packaging design. Die-cutting and creasing processing not only plays an important role in the final quality and effect of packaging, but also can greatly improve the artistic effect of printed matter. It also gives printed matter new functions and has become an important means of adding value and promoting printed matter. Therefore, die-cutting and creasing technology is becoming more and more popular and its use is becoming wider and wider. However, in the die-cutting and creasing process, a series of problems often occur, which affect the smooth progress of production. For this reason, this article takes the common problems of the horizontal flat die-cutting machine in the die-cutting and creasing production as an example to analyze , I hope it will be helpful to actual production.

The paper feeding and delivery principles of the fully automatic horizontal flat die-cutting machine are similar to those of the offset printing machine. The faults will not be analyzed here. The following is just a discussion of common problems in the die-cutting part. .

Uneven pressure

There are generally two situations when the pressure is uneven during the die-cutting and creasing process:

1. If the pressure is slightly uneven, It may be due to the uneven distribution of die-cutting knives and wires (steel knives, steel wires) that the moving platform is skewed during die-cutting. At this time, a balancing knife line should be installed on the die-cutting plate to make the platform bear force. Evenly.

2. If there is serious pressure unevenness at the four corners of the platform, it is mainly caused by the inconsistent heights of the four connecting rods supporting the moving platform. At this time, the die-cut base should be opened. Guard, check whether the swing rod is worn. If the wear is serious, it needs to be replaced. Otherwise, the four pressure adjustment inclined irons need to be adjusted until the pressure is consistent.

Die-cutting accuracy is not high

Die-cutting accuracy is one of the most important standards for measuring die-cutting quality and an important guarantee for producing qualified products. In the actual production process, It often happens that the die-cutting accuracy fails to meet the design requirements. There are many factors that affect die-cutting accuracy, mainly including 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, the chain can only be replaced.

2. The intermittent mechanism is worn, causing the tooth row to vibrate during the stop or start process, thus affecting the die-cutting accuracy. In this case, it generally only affects the positioning accuracy. At this time, the intermittent mechanism should be inspected and repaired.

3． The positioning distance between the front and rear positioning swing frames 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, thus affecting 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 tooth row by 2 to 3 mm.

4. The upper die-cutting plate or the lower die-cutting plate is not positioned accurately. Long-term use of the machine will cause the die-cutting frame or the positioning block on the die-cutting base plate to wear, resulting in an excessive fit gap and reduced die-cutting accuracy. The positioning block should be replaced at this time.

5. The wear of the side positioning plate is an important factor causing inaccurate side positioning. Since the amount of positioning movement is not enough to compensate for the amount of wear, the side positioning accuracy will deteriorate. At this time, the side positioning plate should be replaced.

6. The pressure of the gripper is too small or uneven. If the elasticity of the movable teeth of the paper gripper becomes smaller due to long-term use, it will cause the paper to slip or fall off during the transfer process, thus directly affecting the die-cutting accuracy; uneven pressure between the paper gripper teeth may cause the paper to slip during die cutting. Skew in the process. The movable teeth should be replaced at this time. In addition, the fixed teeth should also be at the same horizontal height, otherwise it may cause paper collision when holding the paper or the paper will wrinkle after holding the paper, affecting the die-cutting accuracy.

7. The cardboard deforms or stretches during the operation, causing inaccurate "overprinting" and thus affecting the die-cutting accuracy. Appropriate paper should be selected to reduce the impact of material defects on die-cutting accuracy.

8. The operator's operating errors lead to insufficient accuracy, or the die-cutting accuracy does not meet the requirements due to the low accuracy of the die-cut version itself. At this time, operators should be professionally trained, production management requirements should be improved, or the die-cutting plate should be remade.

Die-cut loose version

The so-called loose version refers to the phenomenon that the waste edges and cardboard are scattered during die-cutting, resulting in poor paper feeding. When the loose version is serious, it will affect normal production. The main causes of loose plates are errors in the die-cut plate making process and improper selection of elastic strips (or sponges); at the same time, other factors may also cause loose plates.

1. When making die-cutting plates, if the shape of the job is complex or there are many jobs arranged, and the die-cutting connection points are very small or few, it is easy to cause the plate to fall apart during die-cutting. At this time, the number of connecting points should be appropriately increased, and if possible, the length direction of the job should be consistent with the paper transport direction.

2. If the elastic strip (or sponge) on the die-cut plate is too soft and cannot bounce the paper smoothly, it will also cause the plate to fall apart. At this time, high-quality elastic strips (or sponges) with high hardness and good elasticity should be used.

3. Starting the pressure discharge too early is also an important reason for the loose version. After die-cutting, when the moving platform descends, although the paper has been bounced away from the knife line by the elastic strip (sponge), the elastic strip (sponge) is generally 2 to 3 mm higher than the knife line. At this time, if the paper gripper row When it starts to move, the elastic strip (sponge) will still press the paper against the die-cutting bottom plate and it will easily tear the paper and cause the paper to fall apart. At this time, the coupling sleeve between the intermittent mechanism and the main sprocket shaft should be loosened and adjusted so that when the moving platform drops by 7 to 8 mm from the top dead center (it should be about 10 to 15 mm when die-cutting corrugated paper), the pressure discharge begins to move.

4. In addition, the quality of the die-cut printed matter is also one of the reasons for loose printing. If the quality of the print is too poor and the fibers are too short, it may fall apart during the die-cutting process. At this time, the die-cutting speed can be reduced and the number of connecting points can be appropriately increased.

The cutting edge is not smooth during die-cutting, and may even become fluffy

The main reasons for this phenomenon are related to the quality of the steel knife and whether the steel knife can function normally. The main reasons are as follows: Several situations require sufficient attention.

1. Poor quality of steel knives, lack of sharp edges, and poor die-cutting suitability are important reasons for the edge not being smooth or even fluffing. A high-quality steel knife should be selected according to the different properties of the printed matter to be die-cut to improve its die-cutting suitability. If there are no special requirements, try to use a steel knife with horizontal grain processing.

2. The blade of the steel knife was severely worn and was not replaced in time, so that the steel knife could not function normally. The wear of the steel knife edge should be checked frequently. If the wear is found to be serious enough to affect the die-cutting quality, a new steel knife should be replaced in time.

3. When adjusting the die-cutting pressure, the paper pad on the steel knife is not handled properly, that is, the pressure is not replenished properly, resulting in discomfort of the die-cutting pressure, and the blade is not smooth or fluffed. The die-cutting pressure should be readjusted and the backing paper should be replaced to make the pressure meet the die-cutting requirements.

4. Improper matching and installation of the die-cutting knife and the elastic strip (or sponge) will also cause the above phenomenon to occur. The elastic strip (or sponge) must have enough hardness to compress the paper so that the die-cutting knife can smoothly cut the printed matter. Different paper should use elastic strips (or sponges) with different hardnesses. At the same time, the placement position and The height must also meet specifications.

5. The occurrence of rough edges or fluffing is also related to the flatness of the bottom steel plate and the machine pressure. The bottom steel plate must be flat and should be replaced if necessary.

Exploded lines (exploded color)

Exploded lines refer to paper cracking at the indentation when the product is die-cut or when the finished product is folded. This is a common problem in die-cutting, especially when the weather is dry. It should be analyzed based on the specific situation:

1. The paper is brittle and has low moisture content, especially the paper that has been polished at high temperature, which is prone to explosive lines during die cutting. At this time, adjust the humidity of the paper before die-cutting. You can use a water filter to pass water on the back of the paper to increase its moisture content and make it slightly pliable before putting it on the die-cutting machine.

After die-cutting, if the line breaks when pasting the box, wipe water on the crease to alleviate the line break.

2. There is a large area of ??blue or black and other dark colors on the surface of the printed matter, which is prone to color and line explosion after die-cutting. When printing, add no or less ink additives to the dark ink to enhance the adhesion of the ink on the paper and reduce the phenomenon of color explosion and line explosion.

3. When the thickness of the paper (board) is too large, it is easy to produce burst lines. At this time, the height of the die-cutting steel wire must be selected reasonably.

4. There is an explosive line behind the paper under the steel plate. At this time, the paper should be thinned.

5. When the pressure of the die-cutting machine is too high, the line may explode. At this time, the pressure should be reduced so that the waste edges are just separated.

6. The indentation mold or base paper is too thick, the indentation is narrow, and the line is prone to explosion. An indentation mold with appropriate thickness should be selected, and the indentation width should be moderate.

7. The paper powder dropped from the incision accumulates in the groove and leads to explosive lines. The operator should promptly remove paper dust, foreign matter, etc.

Irregular indentation lines

The main reason for irregular indentation lines is that the indentation groove on the steel wire backing paper is too wide, and the position of the cardboard is uncertain when indenting; The thickness of the steel wire backing paper is insufficient, the groove angle is irregular, and there are redundant rounded corners; the arranging and fixing of the knives are not appropriate, the steel coin is too tight, the bottom cannot achieve ideal contact with the plane of the pressure plate, and twisting occurs easily during indentation ; The steel coin is too loose and easy to move left and right when making indentations. The troubleshooting method is to replace the steel wire pad paper and make the width of the indentation groove appropriate; increase the thickness of the steel wire pad paper and trim the groove angle; and the tightness should be appropriate when the knives are fixed in rows.

When the label is removed after the die-cutting of the self-adhesive film, the label is often stuck and peeled off by the waste material on the edge of the paper during the removal process. Especially for some small-area labels, the phenomenon is more serious. Generally, this problem can be solved from the following aspects:

1. When designing, appropriately increase the label area, the shape should not be too complex, and the labels should be arranged reasonably.

2. Prevent the adhesive viscosity of the self-adhesive tissue from decreasing. Can reduce storage and press room temperatures or increase viscosity.

3. Replace the dull blade or make a new die-cut plate.

4. Adjust the pressure of the die-cutting plate by placing the die-cutting plate underneath, so that the pressure on the die-cutting plate is uniform and the die-cutting indentations are of the same depth.

5. Speed ??up the speed of die cutting and waste removal.

The problems discussed above are some common problems in production. In actual production, there will be many other problems. We can analyze them based on the specific situation to find out the possible causes and Take appropriate measures to resolve it. Only by constantly summarizing and mastering various techniques in actual production and operations, being familiar with the performance of production equipment, and mastering the various requirements of the production process can we promptly and correctly eliminate various problems that occur in production and ensure smooth production of high-quality products. Create favorable conditions for die-cut and corrugated products.

Reference:/html/Postpress/cutting/20100620/8094.html

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