Quality inspection and acceptance standards for knife plate spring pads

The quality of the die-cutting plate spring pad directly determines the stability of the die-cutting process and product quality. Establishing scientific quality inspection and acceptance standards is the key to ensuring the quality of the purchased spring pads and preventing substandard products from entering the production process. Quality inspection should cover core dimensions such as appearance, dimensional accuracy, material performance, and usage performance. The acceptance process should be standardized and rigorous to ensure that each batch of spring pads meets production requirements.

Visual inspection is a fundamental step in quality acceptance, mainly checking whether there are any defects on the surface of the spring pad. The surface of a qualified spring pad should be flat and smooth, free from defects such as cracking, damage, bubbles, depressions, and impurities. The edges should be neat, free of burrs and flash, with smooth cuts and no obvious skew. The color of the elastic pads should be uniform and consistent, without obvious color differences. During inspection, appearance defects can be checked by visual inspection and touch. For spring pads with impurities or slight burrs on the surface, cleaning and grinding treatment can be carried out. If there are serious defects such as cracking, damage or bubbles, they should be judged as unqualified products and prohibited from being put into storage for use.

Dimensional accuracy detection is the key to ensuring the compatibility of the spring pad with the knife plate and the equipment. The key dimensions such as the length, width, thickness and hole diameter (if any) of the spring pad need to be inspected, and the error should be controlled within the industry standard range: the dimensional error of the conventional spring pad is ≤±0.1mm, and that of the high-precision spring pad is ≤±0.05mm. The thickness uniformity error is ≤±0.03mm, ensuring that the spring pad fits precisely with the installation groove and avoiding installation offset. During the inspection, precision measuring tools such as calipers, micrometers and projectors can be selected. Random sampling and testing should be conducted on each batch of spring pads, with a sampling ratio of no less than 3%. If the sampling is not up to standard, the sampling range should be expanded until all products are inspected, and the non-conforming products should be eliminated.

Material performance testing is the core for evaluating the service life and compatibility of elastic pads, mainly testing indicators such as hardness, elastic recovery rate, wear resistance, and temperature resistance. Hardness testing is conducted using A Shore hardness tester. According to the requirements, the Shore A or Shore D scale should be selected. The test results should be consistent with the parameters provided by the supplier, with an error of no more than ±2 degrees. The elastic recovery rate test is carried out by squeezing the elastic pad under standard pressure, and then measuring the deformation recovery after standing still. The elastic recovery rate of qualified elastic pads should be ≥85% (≥90% for polyurethane elastic pads). The wear resistance test is conducted using a friction testing machine to simulate the friction scenarios in die-cutting operations. The wear amount should be ≤5mg per 1000 frictions. The temperature resistance test is based on the ambient temperature of use. After being left to stand for 24 hours in a high or low temperature environment, the spring pad should show no obvious cracking, hardening or deformation, and its performance should be stable.

The performance testing needs to simulate the actual die-cutting scenario to evaluate the uniformity of pressure transmission of the elastic pad, the auxiliary effect of waste removal, and the coordination with the knife plate, etc. Standard cutting plates and processing materials can be selected, and the spring pad to be inspected can be installed for trial cutting. Observe the quality of the cut edge and the clarity of the indentation of the die-cut product, and judge the pressure transmission effect of the spring pad. Check the shedding of waste materials after trial cutting and evaluate the waste removal auxiliary performance of the elastic pad. Observe the deformation and displacement of the spring pad during the trial cutting process to determine its stability and adaptability. During the trial cutting process, if problems such as incomplete die-cutting, blurred indentation, waste material adhesion, and spring pad displacement occur, it should be determined that the performance is substandard. The cause needs to be investigated. If it is due to the quality of the spring pad, acceptance should be refused.

In terms of the acceptance process, when suppliers deliver goods, they need to provide relevant materials such as product inspection reports and certificates of conformity. After the acceptance personnel verify that the materials are correct, they will conduct sampling inspections according to the above-mentioned inspection standards. Only after passing the inspection can the goods be stored in the warehouse. If the inspection is not qualified, communication with the supplier should be carried out in a timely manner, requesting a return or exchange, and the reasons for non-conformity should be recorded and included in the supplier evaluation system. In addition, an acceptance file should be established to record the procurement information, test results, usage conditions, etc. of each batch of spring pads, which is convenient for traceability and quality control. The procurement and acceptance process should be continuously optimized to ensure the stability of spring pad quality.