Die cutting is a key process in the manufacture of self-adhesive labels. It involves cutting labels into specific shapes and sizes that allow them to be easily applied to various surfaces. However, the die-cutting process can encounter some challenges that affect the quality and efficiency of label production. The main factors affecting the die-cutting of self-adhesive labels can be summarized into three main aspects: label surface materials, self-adhesive materials, and the equipment itself. In this article, we explore these aspects and discuss potential solutions to the challenges.
1. Label surface material:
The surface material of the self-adhesive label plays a vital role in the die-cutting process. Different materials have different properties that affect the cutting process. There are three main factors: the type of surface material, the strength of the surface material, and the thickness of the surface material.
a) Surface material type:
The types of surface materials used in self-adhesive labels vary widely, and each material has unique characteristics that affect die-cutting, mainly including paper and film.
Paper Labels: Paper labels are commonly used and come in a variety of weights and finishes. However, they are more prone to tearing or folding during the die-cutting process, especially if the paper is thin or fragile. When we analyze samples, we often see that some labels have burrs, which is caused by natural fracture due to the thick fibers of the material itself. Therefore, it is important to choose the proper paper thickness and quality for the intended application to ensure smooth die-cutting. Based on the die-cutting principle of paper materials, and considering the wear of the blade, the angle of the paper flattening blade is usually relatively large. Because the angle is large, the extrusion deformation of the material during die cutting is large, and the separation force in the horizontal direction facilitates the separation of materials.
Film labels: Films place higher demands on the die-cutting process than paper materials. Commonly used film self-adhesive surface materials mainly include: PE, PP, PE, polyolefin, PVC, PS, etc., with durability, moisture resistance and chemical resistance. These materials are generally more flexible and less prone to tearing, making them suitable for intricate die-cut designs. However, film labels are difficult to cut accurately due to their inherent elasticity or memory properties. For this reason, the blade of the die-cutting film material should have a sharp edge, a high hardness, and a small angle, usually 37° to 75°. The smaller the angle, the sharper the blade and the easier it is to die cut. If you use a die-cutter with a large angle, not only is it difficult to die-cut, but if the blade is not sharp, the surface material will not be cut through and the bottom paper will break first, and the edge of the finished label will be flanged. Cause glue seepage.
In short, the precision of die-cut film is greater than that of paper materials, so die-cut film materials have certain requirements for equipment precision, die-cut plate precision and backing paper.
b) Strength of surface material:
The strength of the label facestock is another important aspect affecting die cutting. It refers to the ability of the material to withstand the cutting force applied by the die-cutting equipment. Here are some considerations:
Tear resistance: Labels that require high tear resistance, such as those for industrial or outdoor applications, need to be made of materials with sufficient strength. Materials such as synthetic films or reinforced papers can provide the necessary tear resistance to ensure clean, precise cuts during die cutting.
Shear Strength: Shear strength refers to the resistance of a material to cutting forces parallel to its surface. Labels with high shear strength are less likely to warp or tear during the die-cutting process. Selecting a material with the proper shear strength will ensure accurate and consistent die cutting results.
c) Thickness of surface material:
Consistency in thickness is critical to ensure uniform depth of cut and prevent problems such as incomplete cuts or excessive cutting force. Labels with inconsistent material thickness can cause variations in the depth of cut, affecting the quality and appearance of the die-cut label. In addition, the thickness of the material directly affects the depth of die-cutting. The thicker the material, the easier it is to die-cut, and vice versa, the thinner the die-cutting is, the more difficult it is.
Different die cutting equipment may have limitations on the maximum thickness of material they can handle. It is important to consider equipment specifications and select label materials within the recommended thickness range to ensure optimal die-cutting performance.
2. Self-adhesive material
There are two commonly used adhesives in self-adhesive materials: water latex and hot melt adhesive.
Water latex is composed of polymer particles dispersed in water, and the cohesive force is relatively easy to separate from the film. The hot melt adhesive is composed of rubber-like substances with high cohesion, and it is difficult to separate the adhesive films. Due to the strong fluidity of the hot-melt adhesive, if small text is printed on the surface of the adhesive layer, the adhesive will flow once the label has a small displacement during the subsequent compounding and die-cutting process, resulting in printing on it. The text on the screen is slightly shifted, distorted, or blurred. In addition, hot melt adhesives are easily affected by temperature. Generally, when the workshop temperature is lower than 15°C, the release force of the hot melt adhesive material will decrease rapidly. Therefore, in winter, hot melt adhesive materials are particularly prone to the problem of die-cut flying marks.
Therefore, it is recommended that label printing companies try not to choose hot-melt adhesive materials with strong fluidity, but choose water-sol materials with relatively weak fluidity. At the same time, even if you choose a hydrosol material, you must also pay attention to the coating thickness of the adhesive layer. Because whether it is hot melt adhesive or hydrosol material, if the adhesive coating is too thick, it may cause the adhesive to flow slightly, causing the small text printed on it to be deformed.
3. The equipment itself
The precision and alignment of a die cutter is critical to achieving precise and consistent cuts. The machine should be properly calibrated and aligned to ensure proper positioning of the cutting tool and label stock. Misalignment issues can result in incomplete cuts, irregular shapes, or misaligned labels, which can affect the overall quality of the finished label. Regular maintenance and adjustment of the machine and adherence to the manufacturer’s recommendations are necessary to maintain optimum accuracy and alignment.
Also, the cut pressure and speed settings on the die cutter need to be adjusted appropriately for the specific label stock and adhesive being used. Insufficient cutting pressure may result in an incomplete cut or difficulty separating the label from the liner. Excessive cutting pressure can deform, tear or damage labels. Likewise, cutting speed needs to be optimized to ensure clean cuts without compromising accuracy. Proper calibration of cutting pressure and speed parameters based on label material and adhesive properties is critical to achieving consistent and high-quality die-cutting results.
The quality and condition of the cutting tools used in a die-cutter has a major impact on the die-cutting process. Dull or damaged cutting blades can result in poor cut quality, increased cutting force requirements, or damage to label material. Regular inspection and maintenance of cutting tools, including changing blades when necessary, is essential to ensure optimal cutting performance. Using a quality blade and considering the specific blade design for the label material being used can also improve overall die-cutting efficiency and accuracy.
By considering these aspects and implementing suggested solutions, manufacturers can overcome die-cutting challenges and achieve consistent, precise and high-quality self-adhesive labels. Collaboration with material suppliers, adhesive manufacturers, mold designers and equipment experts can also provide valuable insight and support for optimizing the die-cutting process. Through attention to detail and continuous improvement, manufacturers can ensure efficient production and meet the needs of a variety of labeling applications.
