Analysis of Common Problems in Die-Cut Indentation Production

With the development of the society and the continuous improvement of people’s living standards, consumers, in addition to demanding the inherent quality of goods, have also put forward higher requirements for the packaging of goods when they purchase goods. This includes both the requirements for the design of packaging and decorating of goods and the requirements for the quality of post-press packaging processing. It is called indentation to compact the parts of the printed material to produce traces that give it a certain degree of concavity and convexity in space.

The indentation processing technology was originally used only for the molding of paper packaging boxes, and was gradually applied to the surface processing of various types of printed materials, especially the surface finishing of cartons, cartons, trademarks, and artwork. Now, indentation technology is one of the most important means for achieving packaging design. It not only plays an important role in the final quality and effectiveness of the packaging, but also greatly enhances the artistic effect of printed materials and gives new functions to printed products. An important means for value-added and promotional prints. Therefore, the indentation technology is more and more valued by the industry, and the scope of use is also becoming wider and wider. However, in the die-cutting indentation process, a series of problems often occur, affecting the smooth progress of production. For this reason, the horizontal flat platen die-cutting machine is used to analyze the common problems in die-cutting and indentation production as an example. , I hope to help the actual production.

First, the common indentation problem

Fully automatic horizontal flat die cutting machine, the principle of paper feeding and delivery is similar to that of offset printing press. The faults are not analyzed here. The following is only the analysis of common problems in the die cutting section.

Uneven pressure

We know that indentations are line marks caused by folding, squeezing, or wrinkling. The entire process of indentation is: design - proofing - typesetting - loading - pad version - boot - finishing - finished product. During the manufacture of the folding carton, the line mark is a controlled deformation on the cardboard. The indentation principle is that the cardboard is pressed between the two fixed surfaces (male and punch) and the inner fiber structure of the paper is destroyed, causing the paper to be partially delaminated and the outer surface to form concave and convex line marks. When the indentation of the cardboard is folded at either ninety or one hundred and eighty degrees, the internal fiber bonding (cohesion) of the paper is completely separated.

The pressure in the indentation process is not uniform and there are generally two cases: one is a slight unevenness. If the pressure is slightly uneven, it may be due to the uneven distribution of die cutters, wires (steel cutters, steel wires), which causes the force of the movable platform to be skewed during die cutting. At this time, it should be installed on the die cutting board. Balance the knife line to make the platform even. It may also be affected by the direction of the paper fibers. When the paper is perpendicular to the knife line, the impression is better. The other is serious unevenness. If there are serious uneven pressures at the four corners of the platform, it is mainly caused by the inconsistent heights of the four connecting rods that support the movable platform. At this time, the shield of the die-cut base should be opened to check whether the pendulum is worn or not. If the wear is serious, it needs to be replaced. Otherwise, it is necessary to adjust the four pressure adjustment inclined iron until the pressure is the same.

Explosion (explosion)

When the indentation mold (punch) wire is pressed into the groove, the paperboard is subjected to three forces: pressure, tension, and surface tension. In addition to the permanent deformation of the paperboard, these three forces also reduce the cohesion between the fibers of the various layers of the paperboard. When folded, the surface of the paper is subjected to tension while the inner layer is subjected to pressure. If the pressure exceeds the cohesion between the fibers of the paper, the fibers in the interior of the paperboard are broken, and the paper becomes soft and pliable at the fold. However, the pressure should not be too great. When the tension exceeds the cardboard tension, the stranger will break (the cigarette box bursts). The surface tension of the cardboard during die-cutting increases with the number of indentations applied to the paperboard. Burst refers to cracking of the paper at the indentation when the product is die-cut or when the product is folded. This is a problem that often occurs in indentations, especially when the weather is dry. Specific analysis should be based on specific circumstances:

1, paper crisp, low moisture content, especially after high-temperature polished paper, die-cutting explosive line. At this time, before the die cutting, the paper is first wetted, and the back surface of the paper can be used as a water dispenser to increase the water content of the paper to make it slightly flexible, and then it is put on a die cutting machine. After the die-cutting, if the box is burst, it can be wiped at the crease to relieve the bursting condition.

2. The printed surface has a large area of ​​blue or black and other deep-colored fields, which can be explosively colored and burst after die-cutting. When printing, no ink additive is added or reduced in the dark ink to enhance the adhesion of the ink on the paper and reduce the explosion color and popping phenomenon.

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

4, the steel plate after the paper easily lead to burst, this time should be thin pad paper.

5, die-cutting machine pressure is too easy to lead to burst, this time should reduce the pressure, so that the waste edge just separated.

6, indentation mold or bottom touch paper is too thick, narrow indentation, easily lead to burst. Should use the appropriate thickness of the indentation die, the indentation width should be moderate.

7. Accumulation of paper powder in the cuts in the cuts can easily lead to bursts. Operators should promptly remove clean paper and foreign materials.

Indentation lines are irregular (not clean)

An indentation line is a groove mark that allows a bend to be made using a process of imprinting a mark on a substrate with a steel wire. The reason that the indentation line is irregular is mainly because the indentation groove on the steel wire pad paper is too wide, and the position of the cardboard is not fixed when the mark is indented; the thickness of the steel wire pad paper is insufficient, the groove angle is not standardized, and excess fillet appears ; row knife, solid knife tightness is inappropriate, steel is too tight, the bottom can not achieve the ideal contact with the platen plane, indentation prone to twisting; steel money is too loose, indentation is easy to move around. Exclusion method is to replace the steel wire pad, the width of the creasing groove is appropriate; increase the thickness of the steel wire pad, trim groove angle; adjust the position of the template; row cutter knife hand multiple times feel the tightness is suitable.

We know that a good box should have a six-pronged appearance after indentation molding, with straight and straight corners and tight seams. In the production of a large number of ultra-high-volume packaging carton, the drum-type indentation technology is more accurate and the production efficiency is relatively high. The speed ranges from tens of meters to several hundred meters per minute.

Second, the embossing printing and indentation once completed the process

In some parts printing and decorating printing processes, it is often necessary to add some indentation effects, such as sticky notes, memos, book covers, invitation products, and some decorating and printing products (with creases), which are produced according to traditional printing techniques. The printing process is completed and the indentation process is performed. This printing of its production efficiency and product overprint quality, are not satisfactory. The team of the author carried out technological innovations and improvements on the prints containing the indentation process through production practices and explorations, so that the products that originally required two processes to be completed could realize the production process of light and dark one-time printing. This greatly improved the production process. Printing ergonomics and product quality. The process is roughly as follows:

1, improve the lining process. In order to quickly and easily realize the process of printing and indentation at one time, the conventional embossed liner lining process must be improved, ie, the inner liner should be thinned to 0.7 mm, and the amount of dunnage within the interliner layer should be reduced by a moderate amount. Outside the corresponding increase. After the thickness of the outer liner is increased by 0.7mm, the local increase or decrease can be performed very flexibly, which facilitates the rapid realization of the transition of the light and dark one-time printing process. Therefore, the increase and decrease in the adjustment of the outsourced liner material is a requirement that conforms to the characteristics of the embossing and printing one-off printing process and is an important measure to improve the printing efficiency and quality.

2. The selection and correct adjustment of the ink roller. Set printing, creasing in one machine at the same time to complete the imprint, the main principle is to adjust the printing plate surface and the dark line layout and lining surface into a slight difference, so that the printing plate surface is evenly brushed ink and printing pressure, dark marks Or the point-knife plate surface is not covered with ink because it is lower than the printing plate surface, which is the basic requirement for realizing light and dark simultaneous imprinting to ensure the quality of the printed product. To meet the above printing conditions, the precision of the equipment and the quality of the ink roller play a decisive role. In order to make the printing plate surface obtain a more even brushing ink, it will not cause the dark traces to be stained with the slightest ink; the inking roller holes on the printing machine should maintain the center of the circle, so as to prevent the ink roller from rolling unevenly and affect the uniformity of the ink. For shaft misalignment and enlargement caused by wear, it is necessary to promptly repair and make car circle treatment so as to eliminate the phenomenon of rubber dispensing and slippage and ensure normal inking.

In addition, the colloid and shaft head of the ink roller should also maintain a good center of gravity to prevent normal ink and uniform ink from being affected due to eccentricity. At the same time, it is required that the hardness of the rubber roller should be suitable, and the rubber and the cloth will not be even when it is too hard; if it is too soft, it will easily deform due to the thermal friction caused by the rotating friction, so that the dark plate layout will be stained with ink and affect the product quality.

3, layout height adjustment. For printed note products, as long as the letter layout more than 0.7mm pad height, so that it can form a difference with the dark mark layout, easy to make the Mingyin plate receiving ink, and dark printing plate due to lower than the printing plate can not touch the ink . As the bright printing plate surface is increased, the corresponding outer liner must be reduced accordingly. To do this, the outer lining should be made of a 70g kraft paper. However, on the back of this kraft paper, there should be a piece of white paper with a modest web size and a thickness of 0.7 mm, corresponding to the dark mark layout. Bright and dark layout pressure, ensure print quality. If it is a product that needs to be creased, such as a book cover, a book spine, etc., as long as the bottom of the indentation steel blade is grinded down to about 0.7 mm below the surface of the clear printing plate by a grinder, then the indentation knife is directly merged with the printed plate. Group printing, so that when the printing is due to the steel blade slightly lower than the Mingyin layout without ink. However, a hard padding material with a proper amount of padding is applied to the padding part, such as a white paper stick, so as to satisfy the indentation condition so as to realize a one-time printing process with light and dark.

In summary, the use of a single press indentation process not only greatly improves the printing efficiency, but also significantly increases the overprint quality of the product. At the same time, it also reduces the loss of raw materials and improves economic efficiency. Over the years, the author in the production of the machine, the use of dark marks on the products, using a processing process, so that the original need to make two processes to complete the product, one can be better completed. The effect of this process has also been well evaluated by peers and customers, and it is a technological improvement that has value in promotion and use.

Third, the latest development of indentation process

1. The indentation process is more widely used. Thicker paper folding, invitations, tickets, greeting cards, color laser prints, thick media inkjet prints, coupons, tickets, receipts, and other traditional applications more in-depth, while in the wine box, advertising, new business cards, and other new areas Widely involved.

2. Bumps and indentations tend to be completed at one time. The die-cutting indentation process also plays a very important role in the packaging and forming of the cigarette label, because it directly relates to the packaging quality of the tobacco label and whether it can meet the requirements of the cigarette maker cigarette packaging machine. The production of ultra-large-volume packaging boxes such as cigarette labels is often a large-scale, repetitive production. Under the premise of ensuring product quality, the combination of concave and convex and die-cutting indentation processes completes the production of cigarette labels at one time, which not only saves the company's equipment. Investment can also greatly increase production efficiency.

3, indentation accuracy is higher. Some products require a large area of ​​indentation, and the process requirements become embossed. Some products are printed after the indentation, some are printed after the indentation; some are printed in the film and then indentation, various ways tend to be diverse.

In short, the improvement of living standards requires that the quality of our packaging carton is not only technically qualified in terms of hardness, pressure, etc., but also aesthetically beautiful on the viewing level, and requires our indentation technology to continue to surpass the people. Provide more and better products.