Adhesive materials tearing during waste discharge? These reasons should not be ignored!

It is relatively common for the waste edge of self-adhesive materials to break during die-cutting. Once a break occurs, operators have to stop the machine to reorganize the waste edge, which in turn leads to reduced production efficiency and increased raw material waste. So, what are the causes of waste-edge breakage in self-adhesive material die-cutting, and how should one deal with it?



01 Low tensile strength of the material itself causing waste-edge breakage



Some materials, such as coated paper (also known as glossy coated paper), have shorter paper fibers and are relatively fragile. During the die-cutting waste removal process, the tensile strength of the waste edge is lower than the tension imposed by the equipment, making it easy to break.

In such cases, it is necessary to minimize the equipment's waste removal tension as much as possible. If the equipment's waste removal tension has already been set to the lowest level but the problem persists, then during the preliminary process design stage, the waste edge should be designed wider to ensure that waste-edge breakage does not occur frequently during die-cutting.



02 Unreasonable process design / overly narrow waste edge causing breakage



Many labels used for variable information printing on the market come with easy-tear dotted cut lines. Some self-adhesive label processing companies, due to equipment limitations, have to place the dotted cut and border cut on the same die-cutting station. Additionally, due to cost and pricing factors, the waste edge is designed very narrow, usually only 1 mm wide. This die-cutting process demands a lot from the label material, and a small mistake can easily cause waste-edge breakage, thereby affecting production efficiency.

It is suggested that self-adhesive label processing companies, whenever conditions allow, separate the easy-tear dotted cut line from the label border during die-cutting. This not only reduces the frequency of waste-edge breakage but can also significantly increase die-cutting speed. Companies without this condition can address the problem by adjusting the proportion of the dotted cut or removing the part of the dotted cut that extends beyond the label border.



03 Raw material defects causing waste-edge breakage



Breaks in the self-adhesive material can also easily cause waste-edge breakage. This problem is relatively easy to identify and will not be elaborated here. It should be noted that some self-adhesive materials have very small edge defects that are not easily noticeable and require careful observation. For such cases, the defective material should be removed before die-cutting.



04 Excessive adhesive flow or over-application causing waste-edge breakage



The amount of adhesive applied in self-adhesive materials significantly affects their die-cutting performance. Generally, on die-cutting equipment, the self-adhesive material is not removed immediately after die-cutting but is transported forward a certain distance, and only then does waste removal occur. If the adhesive is applied too thickly, during the transport from the die-cutting station to the waste removal station, the adhesive may flow back, causing the already cut self-adhesive face material to stick together, which leads to the waste edge breaking when pulled due to adhesion.

Typically, the coating amount for water-based acrylic adhesives should be between 18 and 22 grams per square meter, while hot melt adhesives should be between 15 and 18 grams per square meter. Exceeding this range greatly increases the chance of waste-edge breakage. Some adhesives, even if not applied in large quantities, can still cause waste adhesion due to their high flowability.

When encountering such problems, you can first observe whether there is a relatively severe stringing phenomenon between the waste edge and the label. If the stringing is relatively severe, it indicates that the adhesive amount is large or its fluidity is strong. This issue can be resolved by applying some silicone oil additive to the die or by heating with an electric heating rod. Silicone oil additive can effectively slow down the backflow of the adhesive, while heating the self-adhesive material can quickly soften the adhesive, thereby reducing the degree of stringing.

05 Die tool defects leading to waste edge breakage

Defective die tools can also easily cause waste edge breakage. For example, small notches on the blade edge can prevent the adhesive face material from being completely cut through. The uncut portion experiences more concentrated force compared to other parts, making it more prone to breakage. This phenomenon is relatively easy to determine because the location of the break is fixed. In such cases, the damaged die should first be repaired before being used for die-cutting.