From Problem to Solution: A Review of Typical Cases of Indentation Strips and Knife Plate Spring Pads

Theoretical knowledge and selection skills can only truly exert their value when they are ultimately applied in actual production. The following reviews the application logic of indentation strips and knife plate spring pads in solving practical problems through two typical production cases, providing practical experience for enterprises to refer to.

Case One: During the production of express delivery cartons by a certain carton factory, problems such as crease cracking (thread bursting) occurred frequently, with a scrap rate as high as 20%. This not only increased the cost of raw materials but also led to delays in order delivery. After investigation, it was found that in order to increase production speed, the factory selected high-hardness (80 Shore) indentation strips and did not adjust the parameters according to the corrugation type of the corrugated board. The three-layer corrugated cardboard used in express delivery cartons has a B-flute type, which is relatively brittle. When the high-hardness crease strips are used to press creases, the excessive compressive stress on the cardboard causes the fibers to break and result in burst lines. Meanwhile, the density of the accompanying knife plate spring pad is too low (0.3g/cm³), and the elastic recovery is insufficient during high-speed die-cutting, resulting in the cardboard not separating from the blade in time and further aggravating the damage at the crease.

Solution: In light of the characteristics of B-flute corrugated board, the creasing matrix is replaced with medium-hardness polyurethane material with a Shore scale of 65. This hardness not only ensures clear crease but also reduces damage to the board fibers. At the same time, a high-elastic knife plate pad with a density of 0.6g/cm³ is selected to enhance the buffering and resetting capabilities, ensuring that the cardboard can quickly separate from the blade. In addition, guide the workers to adjust the creasing pressure according to the moisture content of the cardboard - when the environmental humidity is lower than 40%, appropriately reduce the creasing pressure by 10% to prevent the cardboard from becoming brittle due to dryness and causing the lines to burst. After the adjustment, the factory's scrap rate of express delivery cartons dropped below 3%, saving over 80,000 yuan in raw material costs each month and shortening the order delivery cycle by one day.

Case Two: When a certain gift packaging factory received orders for high-end cosmetic gift boxes, problems such as the gold foil layer at the creasing area peeling off and the edges and corners of the packaging boxes getting burrs occurred. The customer returned the goods multiple times, causing a direct economic loss of 150,000 yuan. After analysis, the root cause of the problem lies in the mismatch between the selected accessories and the material of the special paper: the order uses art paper with gilding on the surface, which is soft in texture and has weak adhesion of the gilding layer. However, the ordinary rubber creasing strip used by the factory has a relatively high hardness (55 Shore), which causes friction and compression on the gilding layer during creasing, leading to its detachment. The spring pad of the knife plate is made of high-hardness material. When cutting the corners of the gift box, the squeezing of the paper causes burrs.

Solution: Customize 40 Shore degree flexible silicone creasing strips. This material has soft elasticity and adheres evenly to the paper surface during creasing, avoiding excessive local pressure that could damage the gilding layer. The use of low-hardness and high-toughness knife plate spring pads in conjunction reduces the compression on the paper during cutting and simultaneously enhances the smoothness of the cutting edge. In addition, adjust the die-cutting process parameters, reducing the die-cutting speed from 400 times per minute to 250 times per minute to ensure that the accessories and materials have sufficient working time. After the improvement, the gold foil layer peeling rate of the cosmetic gift box was zero, and the burr problem was completely solved. Not only were customer orders retrieved, but also long-term cooperation opportunities were obtained with high-quality products.

These two cases fully demonstrate that the application of indentation strips and ejection rubber is not merely a matter of "installation and use", but rather requires precise matching in combination with material properties and process requirements. When problems arise in production, starting from aspects such as accessory selection and parameter adjustment can often lead to efficient solutions, achieving a dual improvement in product quality and production efficiency.