Post-process technology sharing: common die-cutting indentation problems and countermeasures

Post-process technology sharing: common die-cutting indentation problems and countermeasures

1. The position of the die-cutting indentation line does not match the position of the printed product

　　 (1) There is an error in the production process of the die cutter version. Manual plate making cannot achieve ideal die-cutting and indentation accuracy due to limitations of technical personnel and operating equipment. For some products that require high die-cutting accuracy, laser plate making can be used instead.

　　 (2) Cardboard mouths have different rules. If the cardboard gripper specification error is large, it may be that the back positioning (also called secondary positioning) of the die-cutting machine is too small to move. It can be solved by adjusting the rear positioning and increasing the moving distance of the rear positioning.

　　 (3) Die-cutting impression and printing position are not aligned. The solution is to re-calibrate the die-cutting plate according to the product requirements, and set the printing and die-cutting indentation positions. In addition, it can also be corrected by adjusting the paper conveying side positioning rule or the front positioning rule, so that the die-cutting indentation line is in register with the printing grid.

　　(4) In addition, the working environment of die-cutting indentation is different from that of printing, which will cause deformation or stretching of cardboard fibers, and inaccurate position of die-cutting indentation. The solution is to try to ensure that the die-cutting indentation and printing are carried out in the same working environment or to ensure the identity of the working environment (that is, the same temperature, humidity, etc.).

　　2, the precision of die-cutting is not high

　　 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 out, which causes the teeth row to shake during the stop or start process, which affects the accuracy of die cutting. In this case, it generally only affects the positioning accuracy. At this time, the intermittent mechanism should be overhauled.

　　 (3) The positioning distance of the front and rear positioning swing frame 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 the front and rear positioning, which will affect the accuracy of die-cutting. 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 teeth row by 2 to 3 mm.

　　 (4) The positioning of the upper die-cutting plate or the lower die-cutting plate is incorrect. Long-term use of the machine will cause the positioning blocks on the die-cutting plate frame or die-cutting bottom plate to wear out, which will cause the matching gap to be too large and reduce the die-cutting accuracy. At this time, the positioning block should be replaced.

　　(5) Wear of side positioning plate is an important factor causing inaccurate side positioning. Since the amount of positioning toggle is not enough to make up 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 gripper pressure is too small or uneven. If the elasticity of the movable teeth of the grippers 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 be 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 collisions or wrinkles after the paper is gripped, which will affect the accuracy of die-cutting.

　　(7) The cardboard is deformed or stretched during operation, causing inaccurate "overprint", which affects the accuracy of die-cutting. Appropriate paper should be selected to reduce the influence of material defects on the accuracy of die-cutting.

　　 (8) The accuracy of the operator is insufficient due to operating errors, or the accuracy of the die-cutting version is not high and the die-cutting accuracy cannot meet the requirements. At this time, professional training should be carried out for operators, production management requirements should be improved, or die-cutting plates should be re-made.

　　3. Line burst at the indentation (color burst)

　　 burst line refers to the paper cracking at the indentation when the product is die-cut or the finished product is folded. This is a common problem in die-cutting, especially in dry weather. Specific analysis should be based on specific conditions:

　　 (1) The paper is brittle and has low water content, especially the paper that has been polished at high temperature, which may explode during die cutting. At this time, adjust the humidity of the paper before die-cutting, and use a water-passing machine to pass water to the back of the paper to increase its moisture content and make the grade a little more flexible, and then go to the die-cutting machine. After die-cutting, if the line bursts when pasting the box, wipe water at the crease to relieve the line bursting.

　　 (2) There are large areas of deep blue or black solid on the surface of the printed matter, which is easy to explode after die cutting. No or less ink additives are added to the dark ink during printing to strengthen the adhesion of the ink on the paper and reduce the phenomenon of color bursting and line bursting.

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

　　 (4) Explosive line after the steel plate is filled with paper, the paper should be thinned at this time.

　　 (5) When the pressure of the die-cutting machine is too high, it is easy to explode. At this time, the pressure should be reduced to make the waste edges just separate.

　　 (6) The indentation die or bottom 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 dropped from the incision accumulates in the explosive line in the groove. The operator should promptly remove clean paper, foreign matter, etc.

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