How to deal with burrs on die-pressed cartons?

Analysis of the Causes and Improvement Methods of burrs in carton Die-cutting

During the production process of carton packaging, the burrs generated by the die-cutting procedure not only affect the appearance of the product but also have a certain impact on the overall quality and performance of the packaging box. The occurrence of burrs in the die-cutting process is one of the more common phenomena in packaging processing.

I. Main Causes of burrs

The burrs in the die-cutting of cartons are usually influenced by multiple factors such as material properties, die state, pressure Settings and environmental conditions.

Characteristics of paper materials

Paper quality is one of the fundamental factors influencing the die-cutting effect. When the surface strength of the cardboard is insufficient and the bonding force between fibers is weak, it is prone to powder and fiber shedding during die-cutting, resulting in fine frayed edges.

Cardboard with poor strength has limited fiber toughness and strength, and the paper is relatively brittle, making it difficult to fully withstand the pressure during die-cutting, which may lead to edge cracking or fuzzing.

Die status and selection

The condition of die-cutting blades directly affects the cutting effect. Using a die-cutting knife with an insufficiently sharp edge or an uneven surface with burrs can easily cause burrs when die-cutting cardboard.

Blades made of steel with insufficient hardness and not sharp enough edges tend to break paper products by pressure rather than cut them neatly, which can lead to the formation of burrs and rough edges. When the embossing plate has been in use for a long time and there are many tool marks on its surface, it is also easy for the edges of the die-cut lines of the product to become rough.

Pressure parameters and elastic pad configuration

The setting of die-cutting pressure is quite important for product quality. Excessive pressure may cause the cutting edge of the steel blade to deform, resulting in rough edges of the die-cut line of the product. Insufficient pressure, however, will prevent the cardboard from being completely cut, causing pulling and fuzzing.

The selection and installation of die-cut elastic pads also require attention. If the elastic pad is too hard or too thick, it will exert a considerable squeezing force on the cutting edge of the steel blade during the closing process, which is likely to cause deformation of the cutting edge. If the elastic pad is too soft, it will not have sufficient hardness to press the paper tightly, resulting in the die-cutting knife not being able to cut the material smoothly.

Influence of environmental conditions

Environmental humidity has a direct impact on the moisture content of cardboard. When the environmental humidity is lower than the moisture content of the corrugated cardboard itself, the cardboard will dehumidify, resulting in a decrease in moisture content and making it brittle. In this case, when die-cutting is carried out, corrugated cardboard is prone to edge cracking, which can lead to fuzzing.

Ii. Reference to Practical Cases

Some enterprises encountered the problem of fuzzing at the edges of corrugated cardboard when processing packaging boxes for notebook computers. The technical team made attempts such as adjusting the environmental humidity, replacing the die-cutting steel knife, adjusting the die-cutting pressure and replacing the die-cutting spring pad according to the conventional thinking, but the improvement effect was limited.

Upon further observation, it was found that due to the hollow nature of corrugated cardboard itself, the surface paper undergoes significant deformation during die-cutting, resulting in shrinkage and tension between the two box types. When corrugated cardboard is cut simultaneously, the die-cutting steel knife will come into contact with the cardboard and cause tearing, resulting in burrs.

In response to this situation, the technical team selected die-cutting spring pads with greater hardness and simultaneously pasted double die-cutting spring pads on both sides of the die-cutting steel knife. This measure enhances the clamping force on corrugated cardboard, reducing deformation and tearing during die-cutting. After re-die-cutting, the problem of fuzzing at the edges of corrugated cardboard was improved.

Iii. Improvement Methods and Operational Suggestions

Material selection and pretreatment

When purchasing cardboard, you can inform the supplier that you need cardboard with better strength and toughness. High-quality cardboard has relatively longer fiber lengths and better strength performance, which can resist tearing during die-cutting.

For materials with relatively average paper quality that have been purchased, water and air pressure can be applied to the paper before printing. Under the pressure, some paper fibers and powder can be adsorbed onto the blanket, reducing the occurrence of paper fuzzing and powder shedding.

Selection and maintenance of die-cutting molds

Choosing a die-cutting knife of better quality helps maintain the die-cutting quality. The appropriate steel knife should be selected based on the characteristics of the printed matter to be die-cut. In the absence of special requirements, a steel knife with transverse texture treatment can be considered, as its cutting effect is relatively smooth.

Adjustment of process parameters

The adjustment of die-cutting pressure should be such that it can smoothly cut off the scraps. Excessive pressure will accelerate the wear of the blade, while too little pressure will prevent the cardboard from being completely cut.

It is quite important to make a reasonable selection and installation of die-cutting elastic pads. For hollow structure materials such as corrugated cardboard, die-cutting elastic pads with higher hardness can be selected, and double die-cutting elastic pads can be simultaneously pasted on both sides of the die-cutting steel knife to increase the clamping force.

Environmental control

The production environment should maintain an appropriate humidity level, generally controlled between 50% and 60%, to prevent the cardboard from being too dry or too damp. For paper that has been affected by the environment, it can be hung and dried by a paper drying machine to make the moisture content on the paper surface uniform and consistent, and maintain a relative balance with the workshop environment.

Iv. Systematic Improvement Ideas

The problem of burrs in die-cutting of cartons requires systematic consideration. From material selection to process parameter adjustment, every link deserves attention.

Establishing a record of die-cutting process parameters and summarizing information such as pressure and elastic pad configuration under different paper types and environmental conditions is conducive to accumulating experience.

Regularly inspect the condition of the die-cutting die, arrange a reasonable maintenance cycle based on the production situation, and at the same time pay attention to checking the flatness of the die-cutting platform to avoid uneven pressure caused by platform wear.

By systematically analyzing factors such as materials, die-cutting molds, pressure and the environment, and taking corresponding improvement measures, the problem of burrs in carton die-cutting can be well controlled, supporting the stability of production quality.

Contact information for Shenhua Printing Materials: Mr. Ji, 19924506937