Post-pass Technology Sharing: Common Die-cutting Indentation Problems And Countermeasures

Post-pass 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-cutting knife version. Manual plate making cannot achieve the ideal die-cutting and indentation accuracy due to the limitations of the level of technicians and operating equipment. For some products that require high die-cutting accuracy, laser plate making can be used instead.

(2) There are different rules for cardboard mouths. If the specification error of the cardboard mouth is large, it may be that the rear positioning (also known as secondary positioning) of the die-cutting machine is too small, which can be solved by adjusting the rear positioning and increasing the rear positioning toggle distance.

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

(4) In addition, the different working environment of die-cutting indentation and printing will cause the cardboard fiber to deform or stretch, and it will also cause the inaccuracy of the die-cutting indentation grid. 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 precision of die cutting, mainly in the following aspects:

(1) The wear and elongation of the main drive chain 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, only the positioning accuracy is generally affected. In this case, the intermittent mechanism should be overhauled.

(3) The positioning distance of 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 the 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 2-3mm distance is appropriate.

(4) The positioning of the upper die-cutting plate or the lower die-cutting plate is not accurate. The long-term use of the machine will cause the die-cutting frame or the positioning block on the die-cutting bottom plate to wear, so that the matching clearance is too large and the die-cutting accuracy is reduced. At this time, the positioning block should be replaced.

(5) The wear of the side positioning plate is an important factor causing the inaccurate side positioning. Since the toggle amount of the positioning is not enough to make up for the wear amount, the side positioning accuracy will be deteriorated. 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, the paper will slip or fall off during the transfer process, which will directly affect the die-cutting accuracy; uneven pressure between the grippers may cause the paper to die during die-cutting. skew in the process. At this time, the movable tooth should be replaced. In addition, the horizontal height of the fixed teeth should also be the same, otherwise, the paper may collide with the paper or wrinkle after the paper is grasped, which will affect the die-cutting accuracy.

(7) During the operation, the cardboard is deformed or stretched, resulting in inaccurate "overprinting", thus affecting the die-cutting accuracy. Appropriate paper should be selected to reduce the influence of the defects of the material itself on the die-cutting accuracy.

(8) Insufficient precision caused by operator error, or the die-cutting precision cannot meet the requirements due to the low precision of the die-cutting version itself. At this time, professional training for operators should be carried out, production management requirements should be improved, or die-cutting plates should be remade.

3. Explosion line at the indentation (exploding color)

The burst line refers to the cracking of the paper at the indentation when the product is die-cutting or the finished product is folded. This is a recurring problem in die cutting, especially in dry weather. It should be analyzed on a case-by-case basis:

(1) The paper is brittle and has low water content, especially the paper polished at high temperature, which is easy to explode when die-cutting. At this time, the paper should be moistened before die-cutting, and the back of the paper can be watered with a water filter to increase its water content to make the grade slightly more flexible, and then put on the die-cutting machine. After die-cutting, if the wire burst when the box is pasted, you can wipe water at the crease to relieve the burst wire.

(2) There are large areas of dark colors such as blue or black on the surface of the printed matter, which are prone to burst colors and lines after die-cutting. When printing, no or less ink additives are added to the dark ink to enhance the adhesion of the ink on the paper and reduce the phenomenon of burst color and line burst.

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

(4) There is an explosive line after the paper is placed under the steel plate, and the paper should be thinned at this time.

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

(6) The indentation die or bottom touch paper is too thick, the indentation is narrow, and the line is explosive. The indentation die of appropriate thickness should be selected, and the indentation width should be moderate.

(7) The paper powder dropped by the incision accumulates in the groove, which is an explosive line. The operator should remove clean paper dust and foreign objects in time.