Every Die-hard Die-cutting Die-cutting Process Application (2)

Ebb Tide, natural selection, survival of the fittest

In order to produce products with smooth and sharp edges, we must grasp the key points:

Die-cut design

Before the die-cut version is made, it must be carefully designed and calculated. Circular die-cutting and paper drawing must be considered comprehensively. For example, the cutting cylinder of a circular press die cutter wears, reduces the diameter of the drum, and thus changes the surface speed of the bottom drum, and ultimately results in inconsistent surface speed of the printing roller, the traveling speed of the cardboard, and the surface speed of the bottom roller. Normally, the last carton will cut shorter than the first carton. When designing, there are several principles that should be followed:

Corners should be rounded at the turn of the knife line to avoid vertical steel knife splicing. The junction of the two lines should prevent sharp corners. Avoid sharp lines that cut off from the middle of another straight line. This will make it difficult to secure the knife and loosen the steel knife.

Knife selection

The die cutter is divided into a soft knife and a hard knife. The soft knife is only quenched at the cutting edge of the knife to meet the hardness requirements. The software knife line can be bent out of a smaller arc and radius; the hardware knife is the overall hardening of the die cutter, and the blade body has a higher overall strength.

According to the shape of the cutting edge, there are standard and double-peak cutters. When the die-cut thickness is greater than 0,5mm, it is recommended to use the double-peak cutter. This cutter has two inclined cutters, which can effectively reduce the negative effect of the two convex surfaces. And the edge is extremely sharp and easy to cut into cardboard.

The standard knife specifications are 0.71 X 23.8mm, 7.07 X 23.8mm, 1.42 X 23.8mm, and the height specifications of the high knife are 30mm, 32mm, 40mm, and 50mm. It should be based on the specific product thickness and the thickness of the die plate.

Indentation line selection

The selection principle of the indentation line is: the thickness of the indentation line is greater than the thickness of the paper. The height of the indentation line is equal to the height of the die cutter minus the thickness of the paper minus 0.05 mm to 0.1 mm.

In order to prevent die-cutting cracking and bursting, a wider indentation line should be selected according to the product thickness.

The author's experience is that there is a crack problem in a C-carton that is produced. The measures taken are to use double-track indentation lines and cover the surface of the carton.

Open point

In die-cutting platemaking, the open joint is an indispensable process in the open side. The joint is a small mouth with a certain width at the edge of the die-cutting blade, so that the finished product and the waste edge are still partially connected during the die-cutting process. Place, so that the next step paper, paper delivery / is smooth.

Open the connection point should use special equipment: Knife line opener, grinding wheel to open the connection point, do not use a hammer and tweezers to open the connecting point, otherwise it will damage the knife line and angle, and easy to produce glitches in the connecting part. Do not open the connection point in this position because the die cutter crosses the bridge because it is floating. Widths are 0. 3mm, 0.4mm, 0.5mm, 0,6mm, 0.8mm, 1. Omm et al. use 0.8mm thick discs for corrugated board or corrugated board. Regardless of the size of the connecting point, it is usually used in hidden places that cannot be seen in the molded product. The smaller the connecting point should be, the better the appearance after molding, so as not to affect the appearance of the finished product box.

Die-cutting points are small, with few points. If the shape of the work is: if the crucible is complex or there are many work arrangements, and the die cuts are small and the joints are small, it is very easy to cause die-cutting. The solution is to increase the number of connected points appropriately. In addition, when making a plate, try to keep the length of the print in the same direction as the paper.

Sponge stick

When the sponge strip is used in die cutting, it will be compressed and deformed. If the sponge strip is too close to the knife line, it will cause the sponge strip to generate a lateral force when it is pressed, which will easily damage the joints of the paper or cause the paper to be die cut. Pulling hair, shadows, to the cutting effect; if the knife is too far away from the knife, it will not prevent cardboard sticking knife. The sponge strips are usually placed 1 mm away from the die cutter and 1.5 mm above the die cutter.

The reason why the cardboard sticking knife is cut during die cutting is that the stripping sponge sticked on the die cut plate has a low hardness. If the sponge is too soft, the paper cannot be smoothly removed from the die cutter or indentation line, resulting in a paste plate. The solution is to replace it with a sponge that is hard and elastic.

Indentation Mold

The most primitive method is to put thick cardboard on the cutting table. After the card is punched, the grooves are cut out according to the indentation. However, this method can easily cause the problem of indentation, line burst, or cracking after forming. Most of them are now using the indentation bottom template. The production is simple, quick and convenient, and has strong durability and low price. It is suitable for different needs of short, medium and long editions. Therefore, the development in recent years should be rapid.

Improper selection of indentation lines and indentation patterns can cause indentation lines to be unclear to form dark lines, and some even burst lines. “Dark line” refers to an indentation line that should not be present; “Fry line” refers to a breakage or partial breakage of the cardboard fibers due to the excessive pressure of the die-cut indentation that exceeds the tolerance of the cardboard fiber. To solve the above problems, in addition to matching the appropriate indentation lines and indentation molds, improve the paper quality or by increasing the ambient humidity, increase the moisture content of the paper, increase the paper toughness to solve.

Use equalizers to improve equipment capabilities

Roller die cutting is die cutting in motion. The roller die and the cardboard are in point-to-point contact during advancement. Therefore, it is difficult to ensure that the size of the carton is completely consistent with the die size. The market demand is getting higher and higher, and poorly-constrained cartons are difficult to pass through automated packaging lines. One of the major causes of dimensional inconsistency is the wear of the bottom roll, which reduces the diameter of the bottom roll, which changes the surface speed of the bottom roll and ultimately results in a shortened length of the carton. In general, the last carton will be cut shorter than the first one. Therefore, when designing a plate, the second edition is made longer, so that the sizes of products produced at the same time in multiple editions tend to be uniform. This method is only negatively compensated, but the best solution at present is the equalizer bottom pad system. No matter how the diameter of the bottom rubber pad changes, the bearing can slide freely on the bottom roller, so that the surface speed of the bottom rubber pad is completely controlled by the cutter die, so that the shape of the carton and the cutter die are exactly the same. In addition, different work environments can cause the cardboard fibers to be deformed or stretched, as well as inaccurate die-cut indentations.

Improve the quality of die-cutting products is a problem. Looking to the future of the die-cutting process, the word-etched etching technology (gas vaporization of the material irradiated by the laser) becomes a deterrent, and the development direction of ghosts. It is very simple, as long as a program; a very large size; accurate, the error in a few thousandths of a millimeter; production efficiency is extremely high. There have been bold predictions that laser etching will replace the traditional die-cutting process within 10 years. Although this is only a part of people's views, but in the future of technological development, with the continuous progress of science and technology, China's "God Five" has achieved great success, then the future development of die-cutting process may be unimaginable.

Author / Jing Bo: Shandong Iowa Packaging Printing Co., Ltd.

Source: Corrugated Box 2005, 9