【Die-cutting Quality Problem Solutions】 How to Improve Die-cutting Precision and Solve Quality Issues during the Die-cutting Process

Die-cutting is a crucial process in various industries, and ensuring high-quality output is essential. Here are some solutions to tackle die-cutting quality issues:

1. Regular Maintenance: Implement a maintenance schedule to keep die-cutting machines in optimal condition. Regularly inspect and clean the blades, ensuring their sharpness and proper alignment.

2. Precision Calibration: Regularly calibrate the die-cutting machine to ensure precise cutting accuracy. This includes checking and adjusting the pressure, speed, and positioning systems.

3. Material Selection: Choose appropriate materials that are compatible with the die-cutting process. Consider factors like material thickness, flexibility, and durability to prevent issues during cutting.

4. Test Cuts: Before mass production, conduct test cuts on sample materials to evaluate the die-cutting quality. This allows for adjustments and optimizations to be made before full-scale production.

5. Operator Training: Provide thorough training to operators on proper machine operation techniques, including loading materials, adjusting settings, and troubleshooting common die-cutting issues.

6. Quality Control: Implement a comprehensive quality control process to detect and rectify any die-cutting defects. This may involve visual inspection, dimensional measurements, and verification of finished product specifications.

7. Continuous Improvement: Regularly review and analyze die-cutting processes to identify areas for improvement. Encourage feedback from operators and seek innovative solutions to enhance quality and productivity.

By implementing these solutions, companies can enhance die-cutting quality, minimize defects, and achieve consistent and high-quality output in their production processes.

This article analyzes die-cutting and provides solutions to six quality problems that may occur during the die-cutting process, including low precision, micro deformations caused by habitual cutting, improper positioning or insufficient penetration of crease lines, and other related issues. 

1. Low Die-cutting Precision

The reasons for low precision lie in the die-cutting die itself as well as the printed materials. Hand-made dies may have larger errors, and the difference in working environment between die-cutting and printing can cause paper deformations, resulting in inaccurate crease positions. This problem becomes more severe when dealing with varnished or laminated paper, affecting the die-cutting precision.

Solution: Choose advanced die-making techniques to improve die-cutting accuracy. Try to ensure that die-cutting and printing are conducted in the same working environment or maintain consistency in environmental factors such as temperature and humidity. Apply special treatments for varnished and laminated papers to reduce their impact on die-cutting precision.

2. Smoke Lines and Burrs Produced by Die-cutting

"Bursting" refers to situations where the die-cutting pressure exceeds the limit that paperboard fibers can withstand, causing fiber breakage or partial separation. "Shadow lines" refer to unwanted crease lines. Generally, these issues arise from inappropriate choice of die-cutting plates, improper adjustment of die-cutting pressure, poor paper quality, inconsistent fiber direction of the paper with the blade direction, or low paper moisture content, resulting in decreased paper flexibility.

Solution: Choose suitable die-cutting plates; adjust the die-cutting machine pressure properly; allow the paper to rest in the workshop for a certain period before die-cutting; improve workshop conditions.

Additionally, a special situation occurs when die-cutting hard cigarette boxes with closely spaced crease lines. If the height of the crease lines is configured normally, excessive tension is normally applied to the paper during die-cutting, leading to bursting. To minimize the tension applied to the paper, two methods can be employed: reducing the height of the crease lines or reducing the thickness of the bottom die. However, these two methods should not be used simultaneously as they may diminish the desired effect. The most effective approach is to lower the height of the crease lines by around 0.1-0.2mm, depending on the paper thickness. For paper above 350gsm, a decrease of 0.2mm is recommended, while a decrease of 0.1mm is suitable for paper below 350gsm.

3. Insufficient Crease Penetration and Inadequate Bottom Fill

Inadequate crease penetration can occur due to the dynamic forces acting on weak crease lines during die-cutting. Insufficient die-cutting pressure can also lead to incomplete bottom fill. To address these issues, replacing the die-cutting plate or increasing the die-cutting pressure can be effective.

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4. Raised Fibers and Dust during Die-Cutting

During the die-cutting process, it is common to encounter issues such as rough cut edges and raised fibers on the die-cut products. This is especially noticeable in areas near the crease lines. The reason for this is that during the die-cutting and creasing process, the rubber strip and crease lines on the die cutting plate exert tension on the paper, which results in the formation of raised fibers when the paper is not completely cut through.

To solve this problem, the first thing is to select different types of die-cutting blades based on the paper. There are two types of die-cutting blades: straight blades and cross blades, and the blades also vary in height. The height and shape of the blade directly affect the die-cutting quality and the lifespan of the die-cutting blade for different types of paper.

In terms of avoiding paper fuzz, straight blades are better than cross blades. In terms of lifespan, shorter blades are better than taller ones. When die-cutting laminated paper, it is advisable to use straight and high-quality blades. The blades should be ground, and it is best not to use a one-time embossing process, as excessive pressure may significantly affect the die-cutting result. However, when working with standard paper, it is recommended to use a cross-cut blade and determine the blade specifications based on the paper's fiber quality.

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5. Die-cutting "Foot version"

Die-cutting "gluing rice" refers to the paper sticking to the die-cutting plate. The reasons for this failure include: the density of the sponge around the die-cutting knife is too small or the hardness is too small, insufficient rebound force, dull cutting edge of the die-cutting knife, and thick paper, causing the knife to stick during clamping or die-cutting. According to the distribution of the die-cutting knives, different hardness sponge strips can be used to replace the die-cutting knives reasonably.

6. Die-cutting "Scattered plate"

The failure of scattered plate in die-cutting is mainly related to the plate making process and sponge adhesive strips. If the shape of the die-cutting job is complex or there are many arranged jobs on the die-cutting plate, but there are few connecting points on the rice, it is easy to cause scattered plate during die-cutting. In this case, the number of connecting points should be appropriately increased. In addition, when making the die-cutting plate, try to keep the length direction of the printed matter consistent with the paper feeding force direction. The hardness of the sponge adhesive strip pasted on the die-cutting plate is too small or too soft, which cannot smoothly separate the paper from the die-cutting knife or leave clear indent lines, which will also cause failures. The solution is to replace it with high-quality sponge adhesive strips with a larger hardness and good elasticity.