Application Adaptation: Selection and Matching Skills of indentation lines and knife plate spring pads

In the die-cutting production of printing and packaging, the reasonable selection and scientific coordination of creasing lines and knife plate spring pads are the keys to improving production efficiency and ensuring product quality. Different substrate materials, die-cutting equipment types and product specifications have different requirements for the performance parameters of the two. Only by achieving precise matching and standardized cooperation can their functional value be fully exerted and problems such as unclear indentation, rapid wear of the die-cutting plate and product size deviation be avoided.

The selection of creasing lines should be based on the characteristics of the substrate and product requirements as the core basis. From the perspective of the substrate material, for thin paper (80-150g/m²), a crease line with a low raised height (0.6-0.8mm) and high hardness should be selected to avoid the crease being too deep and causing the paper to break. For thick cardstock (200-400g/m²), an indentation line with a raised height of 1.0-1.2mm should be selected. At the same time, the toughness of the steel needs to be enhanced to ensure that the creases are full. For multi-layer materials such as corrugated paper, a dedicated corrugated creasing line with a raised height of 1.5-2.0mm is required. The raised part is usually designed as an arc-shaped structure to reduce damage to the corrugated shape. From the perspective of product requirements, for packaging that is frequently folded (such as gift boxes), smooth-surfaced chrome-plated creasing lines should be selected to reduce wear during the folding process. For disposable packaging, ordinary carbon steel creasing lines with higher cost performance can be selected.

The selection of the die-cutting knife plate spring pad should take into account both the specification of the die-cutting knife and the production speed. The height of the die-cutting knife directly determines the compression amount of the spring pad. Generally, the height of the spring pad should be 0.5 to 1.0mm lower than that of the die-cutting knife to ensure that the spring pad can be fully compressed during die-cutting and provide a stable buffering force. For instance, when using a die-cutting knife with a height of 23.8mm, a springpad with a height of 23.0mm should be selected. In terms of production speed, for high-speed die-cutting (with a speed exceeding 3,000 sheets per hour), polyurethane spring pads with fast elastic recovery speed should be selected to prevent the spring pads from not resetting in time, which may cause the knife plate to stick together. For low-speed die-cutting, natural rubber elastic pads can be selected to reduce production costs. In addition, in the irregular-shaped die-cutting scene, the spring pad needs to be cut into a shape that matches the die-cutting knife to ensure that each section of the knife plate can receive uniform buffering protection.

The installation of the indentation line and the spring pad of the knife plate must follow strict operating procedures. Before installation, the surface of the knife plate needs to be cleaned to remove oil stains and impurities, ensuring that the indentation line adheres closely to the knife plate. The indentation line can be fixed by using double-sided tape or rivets. The rivet spacing should be controlled at 50-80mm to prevent the indentation line from shifting during the die-cutting process. The spring pad of the die-cutting knife should be adhered closely to both sides of the die-cutting knife, and the distance from the cutting edge should be controlled at 1-2mm. If it is too close, the spring pad may be cut by the cutting edge; if it is too far, it will not be able to play a buffering role. After installation is completed, a trial die-cutting test should be conducted to check the clarity of the indentation, the dimensional accuracy of the product, and the reset condition of the knife plate. If the indentation is blurry, the height of the indentation line protrusion can be appropriately increased. If the knife plate does not reset smoothly, a more elastic spring pad needs to be replaced.