Frequent die-cutting problems? These four methods must be mastered!

In the production process of self-adhesive labels, the quality of die-cutting will directly affect the production efficiency of the next process - the labeling process, and it is easy to cause label breakage during the high-speed labeling process, causing serious damage to label printing companies. It is a great trouble and loss, and it will also directly affect the aesthetics of the end product and the customer experience. There are many factors that affect the quality of die-cutting, and different label products have different requirements for die-cutting processes, methods, quality, efficiency, and cost control. For the above problems. The author of this article starts with the commonly used die-cutting methods, and sorts out the application status, advantages and disadvantages of various die-cutting methods in the current market for your reference.

Now, self-adhesive label die-cutting methods are roughly divided into four types: CNC cutting machine, flat die-cutting, circular die-cutting and laser die-cutting.

A. CNC cutting machine

From the perspective of cost saving, flat die cutting and CNC cutting machines are the most economical material costs, especially for CNC cutting machines. The cost of consumables is not only low, but also fast and convenient. There is no need to prepare a physical knife plate, an electronic knife layout, The cutting command can be executed through the computer or mobile APP, and one or more special cutter heads start working at the same time, and the cutting work is carried out along the line set by the knife map or the camera automatically finds the edge. The cutting depth of the cutter head is carried out according to the thickness of the material and the pre-set process requirements of the label. During the cutting process, the cutter head can be slightly adjusted according to the actual cutting marks.

In addition, the working area of the CNC cutting machine tool ranges from 300mm to 2000mm or more. The larger the cutting width, the lower the positioning accuracy and repeatability; More, the faster the paper feeding speed. Due to the low price of the CNC cutting machine, it is suitable for small label printing companies, printing agencies or proofing. However, the die-cutting efficiency and die-cutting accuracy of the CNC cutting machine are lower than those of the other three die-cutting methods, and are more suitable for manual labeling.

B. Flat die-cuttin

Compared with CNC cutting machines, the flat die-cutting method is the earliest and most popular die-cutting method used by label printing companies. The knife-making cost of flat die-cutting is low and the knife-making speed is fast (depending on the complexity of the graphics). The blades of flat die-cutting generally adopt manual arrangement or laser cutting, that is, CNC automatic machete and arrangement of blades are installed on medium-density wood boards, and finally the blades with arranged blades are installed on the die-cutting machine knife seat.

Compared with the die-cutting efficiency of CNC cutting machine, the die-cutting efficiency of flat-press die-cutting machine is much improved. The price ranges from 100,000 yuan, suitable for small orders, urgent orders, proofing, relatively narrow printing format, non-high-speed automatic labeling, and die-cutting orders that do not have strict requirements on the cutting marks of the backing paper.

C. Circular die-cutting

Rotary die-cutting, also known as circular knife die-cutting, was first used in the field of post-press processing, and was later widely used in daily chemical, electronics, and pharmaceutical industries. In recent years, with the rapid development of flexographic printing technology and the higher requirements of label printing companies for production efficiency, this die-cutting method has gradually been used as the main die-cutting method.

From the point of view of in-line mode, rotary die-cutting can be divided into in-line die-cutting and offline die-cutting. In-line die-cutting mainly occurs on the flexographic printing machine with its own circular knife die-cutting unit, which can simultaneously complete the die-cutting requirements while completing label printing. Among the customer groups served by the author, in-line die-cutting accounts for about two-thirds, and the speed of in-line die-cutting ranges from tens of m/min to 200m/min. In-line die-cutting can greatly improve production efficiency. Offline die-cutting, convenient for off-line die-cutting requirements after printing such as offset printing, gravure printing and flexo printing.

At present, circular die-cutting is the most efficient die-cutting method with the best die-cutting precision control (±0.0025mm, that is, the die-cutting knife must cut through the glue layer, but does not damage the silicone oil layer). It is suitable for high-speed automatic labeling. , Ultra-thin backing paper (glassine below 40g, PET below 0.030mm) requires no marks, special surface material knife angle control (40°~60°), special treatment of blades such as adding wear-resistant coating (5~10μm Dense chromium salt oxide), anti-stick coating, etc., circular die-cutting has very obvious advantages.

The tools used in circular die-cutting are divided into two types: engraving knife and flexible blade, and the circular die-cutting method of flexible blade is more and more replacing the die-cutting method of circular engraving knife and flat flattening .

The circular engraving knife is a kind of blade that is directly milled out the tip (knife line) by computer-controlled three-axis or multi-axis (CNC) on the 45# steel roller, and then processed by other treatments such as the hardness of the tip. The round engraving knife is integrated with the blade roller body. The flatness is controlled by the precision of CNC. The flatness is high and the operation is simple. Just put the knife roller into the chute and pressurize it. The disadvantage is that the price is more expensive and it is inconvenient to replace. After the tip of the knife is worn out, it needs to be sent back to the supplier for grinding. The cycle used ensures continuous production.

Because label printing companies use different brands of engraving knives, the wear resistance of the knife tip is uneven, and the wear resistance of the knife tip with poor wear resistance is very fast. One problem will be ignored, that is, the deformation rate and hardness of the shoulder iron position of the bottom roller under the die-cutting unit, how much pressure the bottom roller bearing or backup roller bearing can withstand without being damaged, after the shoulder iron position is damaged or the bearing is damaged, It is difficult for the bottom roller to ensure concentric rotation, which brings certain difficulties to precision die-cutting. The author suggests that the pressure should be operated according to the technical guide of the die-cut seat.

The round-pressed round flexible blade is generally selected from European high-quality, high-hardness spring steel, and is engraved by computer program-controlled equipment (CNC) after a strictly controlled chemical etching process. The accuracy of the round-pressed round flexible blade can be controlled within the range of ±2.5μm~±5μm from the same design height to ensure the uniformity of die-cutting, and the higher the accuracy and life of the blade, the higher the price, and the price is determined by the combination Process, knife line length composition, label printing enterprises need to customize different process requirements according to the needs of actual products.

Compared with the round-pressed round engraving knife, the dimensional accuracy between the blade and the blade of the round-pressed round flexible blade is more accurate, and various process requirements can be customized, especially when the wear-resistant coating of the blade is only 5 μm to 10 μm. The hardness can reach 73°～75°, which can not only meet the life requirement, but also protect the equipment well, and reduce the damage caused by heavy pressure. In addition, the delivery time of round-pressed round flexible blades is relatively short, and can be completed within 4 to 5 days. The cost is relatively low, and replacement and backup are more convenient. However, it is necessary to purchase a high-precision magnetic roller for round-pressing flexible blades. When attaching the blade, it is necessary to clean the surface of the magnetic roller and the blade bonding surface to prevent dust and other debris from adhering between the blade and the magnetic roller, which will damage the flatness of the blade. , There is a phenomenon of uneven cutting marks on the bottom paper.

D. Laser die-cutting

Laser die-cutting is a die-cutting method that uses the beam emitted by the laser to focus on the printed material according to the designed knife line shape, and cuts evenly, and the cut marks can reach the micron level.

Laser die-cutting does not need to make a physical knife plate, and can realize fast switching of different order graphics. The cutting graphic design, various graphics and material parameter settings can be completed on the computer, and the depth of the required cutting marks can be automatically generated. At the same time, it can be processed repeatedly. Computer By recalling the previously processed and edited cutting program, the production can be started immediately, which saves the time of die replacement and adjustment in traditional die cutting.

At present, the speed of laser die-cutting is slower than that of traditional die-cutting machines, and the price is high. There is burning phenomenon on the cutting edge, and there is a problem of the minimum line width of the cutting line. It is more suitable for invitations, greeting cards, candy boxes, cake boxes, paper carvings Artwork, paper-cut, gift box, etc., self-adhesive labels are less used.

In short, considering cost control, if the unit quantity is small, you can choose CNC cutting machine and low-speed flattening die-cutting; the product structure tends to be low-speed automatic labeling, manual labeling, and the unit quantity is large, you can choose high-speed flattening and low-speed flattening Rotary die-cutting; the order is large, the product process and materials are changeable, and the requirements for cutting marks are strict, and most of them are high-speed automatic labeling order structures. It is recommended to choose circular die-cutting, which is cost-effective; The field is still a die-cutting method that everyone uses more cautiously. You can choose a suitable die-cutting method according to the product structure. The above only represents personal views, and I hope it will be helpful to everyone.

Thank you for your attention.

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Attn:Hans He

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Email：sales07@dtpapergroup.com

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