Common problems and countermeasures in die cutting and indentation process
We are a big printing company in Shenzhen China . We offer all book publications, hardcover book printing, papercover book printing, hardcover notebook, sprial book printing, saddle stiching book printing, booklet printing,packaging box, calendars, all kinds of PVC, product brochures, notes, Children's book, stickers, all kinds of special paper color printing products, game cardand so on.
For more information please visit
http://www.joyful-printing.com. ENG only
http://www.joyful-printing.net
http://www.joyful-printing.org
email: info@joyful-printing.net
With the development of society and the continuous improvement of people's living standards, consumers in the purchase of goods, in addition to the intrinsic quality of the goods, also put forward higher requirements for the packaging of goods. This includes not only the requirements for the packaging design of the goods, but also the quality of the post-press processing.
Die-cutting and indentation processing technology, suitable for surface processing of various types of printed matter. In particular, the finishing of the surface of various grades of cartons, cartons, trademarks, artworks, etc., is also one of the important means to achieve packaging design. Die-cutting and indentation 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, and also gives new functions to printed matter, which has become an important means of value-added and promotion of printed matter. Therefore, the die-cutting and indentation technology is more and more popular, and the scope of use is becoming wider and wider. However, in the die-cutting and indentation process, a series of problems often occur, which affects the smooth progress of production. For this reason, this paper analyzes the common problems in the production of die-cutting indentation by horizontal flat die-cutting machine. I hope to help the actual production.
The automatic horizontal flat die cutting machine has the same principle of paper feeding and delivery as the offset printing machine. The faults in this case are not analyzed here. The following are only the common problems in the die cutting part.
Uneven pressure
There is two cases of uneven pressure during die-cutting and indentation:
1. If the pressure is slightly uneven, it may be due to the uneven distribution of the die cutter and the wire (steel knife and steel wire), which causes the dynamic platform to be stressed due to the die cutting. At this time, it should be on the die cutting plate. Add a balanced knife line to make the platform evenly stressed.
2. If there is a serious pressure unevenness at the four corners of the platform, it is mainly caused by the inconsistent height of the four connecting rods supporting the moving platform. At this time, the shield of the die-cutting base should be opened to check whether the swinging rod is in check. Wear, if the wear is serious, need to be replaced, otherwise you need to adjust the four pressure adjustment oblique iron until the pressure is consistent.
Die cutting accuracy is not high
The precision of die-cutting is one of the most important criteria for measuring the quality of die-cutting. It is an important guarantee for the production of qualified products. In the actual production process, the die-cutting precision often fails to 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 wears and stretches, which will directly affect the positioning accuracy before die cutting. At this time, only the chain can be replaced.
2. the intermittent mechanism wear, causing the tooth row to shake during the stop or start process, thus affecting the precision of die cutting. In this case, generally only the positioning accuracy is affected. At this time, the intermittent mechanism should be inspected.
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 in the front and rear positioning, thereby affecting the die cutting precision. At this time, the cam position of the adjusting screw of the front positioning pendulum or the rear positioning pendulum should be adjusted, so that the front and rear positioning frame can move the distance of the tooth row by 2 to 3 mm.
4. the upper die cutting or the lower die cutting position is not allowed. Long-term use of the machine will cause the positioning block on the die-cut frame or the die-cut substrate to wear out, so that the matching clearance is too large and the die-cutting precision is lowered. The positioning block should be replaced at this time.
5. The wear of the side positioning plate is an important factor causing the side positioning to be inaccurate. Since the amount of the positioning is insufficient to compensate for the amount of wear, the side positioning accuracy is deteriorated. The side positioning plate should be replaced at this time.
6. The pressure of the gripper is too small or uneven. If the movable tooth elasticity of the gripper becomes small due to long-term use, it will cause the paper to slip or fall off during the transfer process, which directly affects the die-cutting precision; uneven pressure between the grippers may cause the paper to be die-cut. Skew in the process. The active tooth should be replaced at this time. In addition, the fixed teeth should also be consistent in level. Otherwise, it may also cause paper collision or paper wrinkling after creping, which affects the precision of die cutting.
7. During the operation, the paperboard is deformed or stretched, resulting in “overprinting”, which affects the precision of die cutting. Appropriate paper should be used to reduce the effect of defects in the material on the die cutting accuracy.
8. The operator's operation error causes insufficient precision, or the die-cutting precision does not meet the requirements due to the low precision of the die-cut version. At this point, the operator should be professionally trained, improve production management requirements, or re-create the die-cut version.
Die cutting
The so-called loose plate refers to the phenomenon that the waste edge and the cardboard are scattered when the die cutting causes the paper to be unsatisfactory. When the bulk version is serious, it will affect normal production. The main reasons for the dispersal are the mistakes in the die-cutting process and the improper selection of elastic strips (or sponges); at the same time, other factors may also cause the loose plate.
1. When the die-cutting plate is made, if the shape of the job is complicated or there are many pieces of work, and the die-cutting points are small and few, it is easy to cause the plate to be cut. In this case, the number of joints should be increased as appropriate. If possible, the length of the job should be consistent with the direction of paper transport.
2. If the elastic strip (or sponge) on the die-cut version is too soft, it will not bounce the paper smoothly, and it will also cause a loose copy. At this time, a high-quality elastic strip (or sponge) with high hardness and good elasticity should be used.
3. the start of the pressure row too early is also an important reason for the bulk version. After die-cutting, when the moving platform is lowered, although the paper has been ejected from the cutting line by the elastic rubber strip (sponge), since the elastic rubber strip (sponge) is generally 2 to 3 mm higher than the cutting line, at this time, if the paper is arranged, When you start the exercise, the elastic strip (sponge) will still cause the paper to be loosened by pressing the paper against the die-cut base. At this time, the coupling mechanism of the intermittent mechanism and the main sprocket shaft should be loosened to adjust, so that the moving platform is lowered by 7-8 mm from the top dead center (about 10 to 15 mm when the corrugated paper is cut), and the pressing starts to move.
4. In addition, the quality of the die-cut prints is one of the reasons for the loose prints. If the paper quality of the printed matter is too poor and the fiber is too short, it may appear in the die cutting process. At this point, you can reduce the die cutting speed and increase the number of joints as appropriate.
The die edge is not smooth, even fluffing
The main reason for this phenomenon is related to the quality of the steel knife and the function of the steel knife. There are mainly the following situations, which must be paid enough attention.
1. The poor quality of the steel knife, the sharpness of the cutting edge and the poor adaptability of the die cutting are important reasons for the blade being not smooth or even raised. According to the different properties of the die-cut printed materials, high-quality steel knives should be used to improve the die-cutting suitability. If there are no special requirements, the steel knives treated with horizontal stripes should be used as much as possible.
2. The edge of the steel knife is seriously worn and not replaced in time, so that the steel knife can not function normally. The wear of the steel cutting edge should be checked frequently. If the wear is serious and the die cutting quality is affected, the new steel knife should be replaced in time.
3. When the die-cutting pressure is adjusted, the paper pad is not properly treated, that is, the pressure is not compensated, which causes the die-cutting pressure to be uncomfortable, and the blade is not smooth or fluffed. The die-cutting pressure should be readjusted and the padded paper replaced so that the pressure meets the die-cut requirements.
4. The matching and installation of the die cutter and the elastic strip (or sponge) are not in accordance with the specifications, which may also cause the above phenomenon. The elastic strip (or sponge) must have sufficient hardness to press the paper tightly, so that the die cutter can cut the printed matter smoothly. Different papers should be made of elastic strips (or sponges) of different hardness, and at the same time, the position and Height must also meet specifications.
5. the edge is not smooth or raised, but also related to the flatness of the bottom steel plate and machine pressure. The bottom steel plate must be flat and the bottom steel plate should be replaced if necessary.
Explosion line
Explosive line 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 in the case of dry weather. It should be analyzed according to the specific situation:
1. The paper is brittle and the water content is low, especially the paper which has been polished by high temperature and is easy to explode when die cutting. At this time, the paper is conditioned before the die-cutting, and the water can be used to pass the water to the back of the paper to increase the water content, so that the grade is slightly flexible, and then the die-cutting machine is used. If the line is broken after the die-cutting, the water can be wiped at the crease to relieve the explosion.
2. the surface of the printed matter has a large area of blue or black and other dark colors, and it is easy to explode and blast after die cutting. In the dark ink, no ink additive is added or added in the dark ink to enhance the adhesion of the ink on the paper, and to reduce the color explosion and the explosion phenomenon.
3. When the thickness of the paper (board) is too large, it is easy to produce a blast line. At this time, the height of the die-cut steel wire should be reasonable.
4. the steel plate under the pad after the explosive line, at this time should be thinned pad paper.
5. When the pressure of the die-cutting machine is too high, the line is explosive. At this time, the pressure should be reduced, so that the waste edge is just separated.
6. the indentation mold or bottom paper is too thick, narrow indentation, explosive line. Indentation dies of appropriate thickness should be used, and the width of the indentation should be moderate.
7. The paper powder falling from the slit accumulates in the explosive line in the tank. The operator should remove clean paper, foreign objects, etc. in time.
Indentation line irregular
The reason for the irregularity of the indentation line is mainly because the indentation groove on the steel wire pad is too wide, the position of the cardboard indentation is not fixed; the thickness of the steel wire pad is insufficient, the groove angle is not standardized, and extra round corners appear; The knives and solid knives are not suitable tightly, the steel money is too tight, the bottom can not achieve ideal contact with the plane of the pressure plate, and the writhing is easy to be twisted; the steel money is too loose, and the indentation is easy to move around. The elimination method is to replace the steel wire mat paper, and the width of the indentation groove is suitable; increase the thickness of the steel wire pad and trim the groove angle; the tightness of the knife should be suitable when the knife is fixed.
When the adhesive is die-cut and the waste is removed, the label is peeled off.
After the self-adhesive die-cutting, the label is often peeled off by the paper edge scrap during the stripping process, especially for some small-area labels, which 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 the labels should be arranged reasonably.
2. Prevent the viscosity of the self-adhesive paper adhesive from decreasing. Reduces storage or pressroom temperatures or increases viscosity.
3. Replace the blunt blade or re-make the die-cut version.
4. The pressure of the die-cutting plate is adjusted by the method of cutting the bottom plate by the underlying die, so that the pressure of the die-cutting plate is uniform, and the die-cutting indentation is uniform.
5. Speed up the die cutting and waste.
The problems discussed above are some of the common problems in production. In actual production, many other problems will occur. They can be analyzed according to specific situations, find out the possible causes, and take corresponding measures to solve them. Only in the actual production and operation, we will continue to summarize and master various skills, familiar with the performance of production equipment, and master the requirements of production technology, in order to correctly and correctly eliminate various problems in production, and produce high quality for smooth production. Die-cutting products create favorable conditions.