Analysis of Quality Problems in Die-Cutting Process

1. The reason why the accuracy of die cutting is not high is due to the problem of die-cutting and the problem of prints. Hand-made die-cutting plates have a large error; die-cutting indentations can cause paper deformation due to the difference between the print indentation and the printing work environment, leading to inaccurate position of die-cutting indentations, and in particular, the deformation of paper after coating and coating is more serious. Die cutting accuracy.

Solution: Select advanced plate-making methods to improve the accuracy of the die-cut version: try to ensure that the die-cutting indentations are printed under the same working environment or that the operating environment is identical (ie, has the same temperature, humidity, etc.); Light and film-covered sheets require die-cutting pre-treatment to minimize the effect of paper deformation on die-cutting accuracy.

2. Die cut indentation produces burst and dark lines

"Breakout" refers to the fact that the pressure of die-cutting indentation exceeds the tolerance limit of the paperboard fiber and causes the cardboard fibers to break or partially break. "Dark line" refers to an indentation line that should not be present. Generally not suitable for die-cutting and indentation steel wire selection, improper die-cutting pressure adjustment, poor paper quality, inconsistency between the fiber direction of the paper and the direction of the die-cutting plate knife, or the low flexibility of the paper due to the low water content of the paper. of.

Solution: Select the appropriate die-cut version; properly adjust the pressure of the die-cutting machine; place the paper to be die-cut in the workshop for a period of time before die-cutting; increase the humidity of the workshop environment.

There is also a special case where the distance between the indentation lines in many places is very close when the hard box cigarette case is die-cut, if the height of the indentation steel line is configured as normal, the pulling force on the paper during the molding If it is too large, it can also cause a burst. Therefore, efforts should be made to minimize the tension on the paper. There are two methods: one is to reduce the height of the indentation steel wire; the other is to reduce the thickness of the indentation bottom mold strip, both of which cannot be used at the same time, otherwise no good indentation effect is achieved. The preferred method is to reduce the height of the indented steel wire. The reduced height is usually 0.1 to 0.2 mm. According to the paper thickness to determine the specific reduction in the amount of paper in the amount of 350g/m2 above the need to reduce the 0.2mm, 350g/m2 below the paper to reduce the 0.1mm.

3. Indentation line movement position. Not full

The twisting of the indented steel wire under the action of die-cutting pressure will cause the indentation line to move; insufficient die-cutting pressure will cause the indentation not to be full. This problem can be improved by replacing die-cutting plates and increasing the die-cutting pressure, respectively.

4. Die cutting and dusting

During die-cutting, the phenomenon that the trimming products are not smooth and fluffy often occurs, and particularly, some trimming edges closer to the indentation line are more serious. This is due to the fact that during die-cutting and pressing, the strip and creasing steel wire on the die-cut plate exert a pulling force on the paper, and the paper is pulled when the paper is not completely cut.

To solve this problem, first select different types of die cutters for paper. Die cutting knives include straight knife and horizontal knife, the two lines of the blade have a high and low points. The lines and heights formed by the blade are directly related to the cutting quality of different types and different papers and the service life of die cutters. In the avoidance of paper hair, the straight knife is better than the horizontal knife; in the service life, the low front knife is better than the high front knife. When die-cutting coated paper jams, straight-line high-cutting blades should be used, and the blade must be milled. It is better not to use a concave-convex molding process. If the pressure is too high, the die-cut will be greatly affected. In the processing of ordinary cardboard should use a small front knife, and according to the quality of the paper fiber to determine the knife's grain. The straight knife is used when cutting the poor or coarse paper, and the cross knife can be used when the fiber quality is better, so as to increase the service life of the knife.

It is also possible to affix a 60° arched strip to the die cutter near the indentation steel line, reducing the pulling force of the indentation steel wire near the die cutter to the paper when the die is cut and pressed. For example, 0.4mm x 1.3mm indentation line and 23.4mm high indentation steel line are generally used for die-cutting paper with a basis weight of 300g/m2. In case of failure, 0.4mm x 1.2mm indentation lines can be used instead. 23.3mm high indentation steel wire. In this way, the pulling force on the paper when the die-cutting and pressing is reduced, and the problem of fluffing can basically be solved.

5. Die-cut "glue"

Die-cut "glue" refers to the paper sticking to the die plate. The reasons for this failure are: the density of the sponge strip glued around the die cutter is too small or the hardness is too low, and the resilience is insufficient; the cutting edge of the die cutter is not sharp and the paper is too thick, causing the knife to stick when cutting or cutting. According to the distribution of die cutters, sponges of different hardness can be reasonably selected or die cutters can be replaced.

6. Die-cutting "Scattered"

Die-cutting is mainly related to platemaking process and sponge tape. If the shape of the work is complicated or there are many jobs, and the dots on the die plate are both small and small, it is easy to cause die-cutting. In this regard, we must appropriately increase the number of links. In addition, when making a die cut, try to keep the print length direction consistent with the feed direction. The release paper strip glued on the die-cut plate has a low hardness and is too soft to smoothly remove the paper from the die cutter or the indentation steel wire. The solution is to replace it with a high-quality, elastic-quality sponge tape.