Quality control: The core guarantee for the production of indentation lines and knife plate spring pads

The quality stability of the creasing matrix and the spring pad of the knife plate is directly related to the final quality of the printed packaging products. Therefore, the quality control system in the production process is particularly crucial. From raw material selection to finished product inspection, the strict control of each link is the core guarantee to ensure that consumables meet the strict requirements of die-cutting processes. Among them, the precise selection of raw materials, the meticulous operation of production processes, and the comprehensive inspection of finished products constitute the three core links of quality control.

The scientific screening of raw materials is the foundation of quality control. For the indentation line, the purity of the raw material steel is a key indicator. The carbon content of high-quality steel should be controlled between 0.6% and 0.8%, while the content of impurities such as phosphorus and sulfur should be less than 0.03% to prevent the indentation line from breaking due to insufficient toughness of the steel. In the steel procurement process, spectral analysis must be conducted on each batch of raw materials to ensure that their composition meets the standards. For the raw material rubber of the knife plate spring pad, attention should be paid to its degree of polymerization and crosslinking density. The degree of polymerization of natural rubber should be greater than 1000, and the acrylonitrile content of nitrile rubber should be adjusted between 18% and 40% according to the oil resistance requirements. When purchasing, the processing performance of the rubber should be judged through Mooney viscosity test to ensure the stability of subsequent production.

The refined operation of the production process is the core of quality control. The production of indentation lines involves three key processes: rolling, quenching and forming. During the rolling process, the rolling speed should be controlled at 5-8m/min to ensure uniform steel thickness with an error not exceeding 0.02mm. Quenching treatment is carried out by medium-frequency induction heating, with the temperature precisely controlled at 850-900℃, held for 15-20 seconds, and then rapidly cooled to below 200℃ to enhance the hardness of the steel. The forming process uses precision molds to press the steel into a specific raised shape, ensuring that the roundness error of the raised part is less than 0.05mm. The production of the knife plate spring pad focuses on controlling the mixing and vulcanization processes: During the mixing process, rubber is mixed in proportion with carbon black, vulcanizing agents and other additives. The mixing temperature is controlled at 120-140℃, and the time is 8-10 minutes to ensure the uniform dispersion of the additives. During the vulcanization process, the temperature is maintained at 150-160℃ and the pressure at 3-5MPa. The vulcanization time is adjusted according to the thickness of the elastic pad. Generally, for elastic pads with a thickness of 3-5mm, the vulcanization time is 15-20 minutes to ensure the stability of the elastic pad's elasticity.

Finished product inspection is the last line of defense in quality control, and a full-project inspection system needs to be established. The inspection items of the creasing matrix include dimensional accuracy, surface hardness, bending performance, etc. The height of the protrusion and the width of the base are inspected with a vernier caliper, and the error should be controlled within ±0.03mm. The surface hardness is tested by a Rockwell hardness tester to ensure it meets the design requirements. Through repeated bending tests, it is required that the indentation line has no cracks after being bent 180° for 50 times. The inspection of the knife plate spring pad covers indicators such as elastic recovery rate, hardness, and wear resistance: when the spring pad is compressed to 50% of its original height and released, the elastic recovery rate should be greater than 95%. The hardness is tested using a Shore hardness tester, with an error not exceeding ±2 degrees. The wear amount should be less than 0.5mm after 100,000 frictions as tested by the wear resistance testing machine. For products that fail the inspection, it is necessary to trace back to the production stage for process adjustment to form a closed-loop control.