Creasing lines and knife plate spring pads: Core consumables in the die-cutting process of printing and packaging

In the die-cutting and creasing process of the printing and packaging industry, creasing lines and knife plate spring pads are two indispensable core consumables. They work in coordination and directly determine the forming quality and precision of packaging products. The crease line plays a crucial role in forming precise creases on the surface of the substrate, while the spring pad of the die-cutting plate ensures the stable operation of the die-cutting knife through elastic buffering. Together, they form the "precision guarantee system" of the die-cutting process, and their performance has a direct impact on production efficiency and product qualification rate.

Creasing matrix, as special consumables for forming creases, have distinct functional characteristics in structure and material. A typical indentation line consists of two parts: the base and the arc-shaped raised surface. The base is used to fix and adhere to the knife plate, while the arc-shaped raised surface directly contacts the substrate to form an indentation. Depending on the thickness difference of the substrate, the raised height of the creasing line is usually divided into multiple specifications such as 0.8mm, 1.0mm, 1.2mm, etc. For example, when processing 200g/m² cardboard, a creasing line with a raised height of 1.0mm should be selected, while for 5-layer corrugated paper, a product with a raised height of 1.5mm or more should be matched. In terms of material, high-quality indentation lines are mostly made of high-carbon steel or stainless steel. After quenching treatment, the surface hardness can reach above HRC55, which not only ensures clear indentation but also avoids wear and deformation after long-term use.

The core value of the knife plate spring pad lies in its elastic buffering and resetting functions. Its appearance is mostly in the form of long strips or sheets, and the materials are mainly natural rubber, nitrile rubber or polyurethane. The performance of elastic pads made of different materials varies significantly: natural rubber elastic pads have a high elastic recovery rate and are suitable for die-cutting scenarios in ordinary paper packaging. Nitrile rubber elastic pads have strong oil resistance and can be used in processes that come into contact with chemical substances such as ink. Polyurethane spring pads have both wear resistance and aging resistance. Their service life is 2 to 3 times that of traditional rubber spring pads and they are suitable for high-speed continuous die-cutting production. The hardness of the spring pad also needs to be adjusted according to the specifications of the die-cutting knife. Generally, products with a Shore hardness of 30 to 50 degrees are selected. If the hardness is too high, it will cause the knife plate to reset poorly; if it is too low, it cannot provide sufficient buffer protection.

In actual production, the fit between the creasing matrix and the spring pad of the knife plate has a very strong correlation. The installation position of the crease line must precisely correspond to the arrangement of the die-cutting knife to ensure that the dimensional error between the crease and the cutting edge is controlled within 0.1mm. The spring pads of the die-cutting knife need to be installed closely on both sides of the die-cutting knife. When the die-cutting knife moves down for cutting, the spring pads are compressed to store elastic potential energy. After the cutting is completed, the spring pads release energy to push the die-cutting knife to quickly return to its original position, preventing the die-cutting knife from adhering to the substrate. At the same time, it reduces the rigid impact between the die-cutting knife and the equipment, thereby extending the service life of the die-cutting knife. The synergistic effect of the two is the foundation for achieving efficient and precise operation of the die-cutting and creasing process.