Missing or distorted digital hot-stamping patterns? Die-cutting misalignment? These hot tips are not to be missed!!

In recent years, digital printing has been widely applied in the field of self-adhesive label printing, and many industry professionals believe that digital printing is the future main trend for self-adhesive labeling. Against this backdrop, digital post-printing processes that complement digital printing have gradually developed. In this article, the author will introduce several currently popular digital post-printing processes. 01 ONEDigital Cold Foil01Introduction to Digital Cold FoilDigital cold foil refers to a process in which UV glue is sprayed onto the surface of the substrate using a nozzle and then combined with a foil to create a gold-stamped pattern. One characteristic of this process is the ability to foil variable information. Since the UV glue is applied by a nozzle controlled by computer programming, digital cold foil can achieve random pattern changes just like a digital printer, making each label's foil pattern unique. In principle, any pattern within the nozzle's precision range is possible. Another feature is that the foiled patterns have a raised effect, which can completely replace traditional embossing techniques. This is because the amount of glue sprayed can be controlled by the computer, and if the glue quantity is sufficient, the foil patterns will be raised. The raised effect of cold foil patterns is more pronounced and three-dimensional, offering a better effect than traditional embossing.It is important to note that unlike traditional cold foil processes, digital cold foil requires two UV curing steps. Since the amount of glue sprayed is large, it cannot be left to flow on the substrate's surface, as this would affect the foil result. Therefore, after spraying, the glue is immediately passed under a low-power UV lamp for preliminary curing. The purpose is to maintain the glue's shape without fully curing it. After preliminary curing, the glue is combined with the foil and then undergoes a second UV curing, which fully solidifies the glue and bonds it tightly with the foil, ultimately forming the foil pattern.Currently, digital cold foil also has certain limitations. On one hand, the equipment is relatively expensive, with market prices ranging from several hundred thousand to one million yuan. On the other hand, most digital cold foil equipment currently operates at a speed of only 5–20 meters per minute, making large-scale high-efficiency production difficult. Entry-level digital cold foil equipment is more suitable for small batches or personalized orders with variable information.

02Analysis of Common Issues in Digital Cold Foil Stamping(1) Fine text and graphics becoming thick or blurredDigital cold foil stamping works by spraying glue onto the surface of the substrate, and the glue has a certain thickness. During this process, the glue may flow, causing slight distortion of the pattern, and even making fine patterns become thick or blurred. Therefore, special attention must be paid during the pre-print design stage to ensure that the designed pattern matches the post-printing process; otherwise, problems may arise during production which would be difficult to rectify later.Additionally, during production, it is important to control the equipment speed to match the amount of ink sprayed. Once the optimal speed has been determined, it should not be changed arbitrarily, as a mismatch between speed and ink volume can cause the graphics to thicken or blur.(2) Deformation of foil patternsSometimes, foil patterns may deform. This is often due to issues during the pre-curing stage. If the UV lamp power is insufficient, the UV glue does not achieve proper pre-curing and continues to flow on the substrate surface, causing pattern deformation. In such cases, the power of the pre-curing UV lamp should be checked, and it should be verified whether the sprayed glue achieves the desired effect after pre-curing. If it does not, the UV lamp power should be increased.Furthermore, excessive ink volume can also lead to pattern deformation, especially after cleaning the nozzle during production. After cleaning, the increased ink output can easily cause the pattern to deform.(3) Missing foil patternsMissing foil patterns are mainly caused by nozzle clogging. As a rule, nozzles should be cleaned after machine stoppages or after continuous production periods using a dedicated cleaning agent to prevent clogging. If a nozzle is already clogged, it should be immediately unclogged with a specialized cleaning solution.02 TWODigital Die-Cutting01Introduction to Digital Die-CuttingDigital die-cutting refers to a process in which a computer program controls a robotic arm equipped with a craft blade to cut the desired patterns on the substrate material. The advantage of this die-cutting method is its high flexibility, and being a cold die-cutting technique, it does not cause edge shrinkage, darkening, or yellowing, making it suitable for producing small-batch, variable pattern orders in conjunction with digital printing machines. The tools used are relatively inexpensive, resulting in low die-cutting costs, and the market price of the equipment ranges from 100,000 to 250,000 RMB, making the investment relatively small. For some small and medium-sized label manufacturers, this die-cutting equipment is a good choice.Currently, the operating speed of digital die-cutting equipment is only 5~8 m/min, making it more suitable for small-batch orders. It cannot die-cut highly complex patterns and is mainly used for prototyping. Therefore, digital die-cutting has certain limitations.02Analysis of Common Issues in Digital Die-Cutting(1) Die-cutting misalignmentDigital die-cutting equipment uses visual markers to determine the cutting position. If the marker size is incorrect or the color contrast is insufficient during printing, the die-cutting machine's sensor may misread, resulting in misalignment. When printing, attention must be paid to the size and placement of markers. Generally, the marker should be 5 mm x 5 mm, with a minimum size of 3 mm x 3 mm. No other graphics should be printed around the marker to ensure accurate positioning of the die-cutting machine.(2) Incomplete die-cuttingDigital die-cutting primarily uses craft blades to cut the substrate. The blade's lifespan varies depending on the material hardness. If the blade becomes dull, it should be replaced in time; otherwise, incomplete die-cutting may occur. Operators should monitor the blade condition and replace it promptly to prevent incomplete cuts.

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Laser Die-Cutting01Introduction to Laser Die-Cutting ProcessLaser die-cutting is a method in which a laser head, controlled by a computer program, burns the desired pattern on the surface of the substrate material. Each label pattern cut using laser die-cutting can be variable, and very complex patterns can be cut, such as cutting out a world map. Additionally, laser die-cutting equipment operates at a high speed; for regular patterns, it can reach speeds of up to approximately 120 m/min.One significant drawback of laser die-cutting is that the laser generates heat. When cutting softer and thinner film materials, the edges of the labels may shrink or yellow. Moreover, laser die-cutting equipment is expensive, generally ranging from several hundred thousand to one million yuan, and some high-end devices are even more costly. Therefore, for some small and medium-sized label companies, investing in such equipment can be quite challenging.02Common Problems in Laser Die-Cutting and Analysis(1) Cutting Through or Insufficient CuttingThe power of the laser head is set before cutting. If the laser power is too low, it will not cut through the material; if the power is too high, it may cut through or even completely cut the material. Therefore, it is essential to test and determine the suitable cutting power before die-cutting. The cutting power must also match the speed. After setting the power, if the speed of the equipment increases, the power may need slight adjustment, generally increasing slightly. Conversely, if the speed decreases, slightly reducing the power may be necessary. Specific adjustments should be based on actual conditions, and if the impact is negligible, adjustments may not be needed.(2) Lines Too Thick or Too ThinIf the lines of the pattern are too thick or too thin during die-cutting, this is often due to incorrect focus adjustment. In such cases, stop the machine and adjust the focus so that the lines meet the design requirements before continuing with the cutting.(3) Distorted PatternsIf the patterns cut by the laser are distorted, first check whether there is an issue with the computer program. After ruling out computer program issues, if the problem persists, check the mechanical components for looseness or excessive vibration. Generally, computer program issues are more likely and can be resolved by restarting the computer or checking if there are strong sources of interference near it.