{"id":7344,"date":"2025-08-05T10:44:15","date_gmt":"2025-08-05T02:44:15","guid":{"rendered":"https:\/\/www.qualitester.com\/?p=7344"},"modified":"2025-08-05T10:50:08","modified_gmt":"2025-08-05T02:50:08","slug":"stiffness-tester","status":"publish","type":"post","link":"https:\/\/www.qualitester.com\/cs\/stiffness-tester\/","title":{"rendered":"Osvojen\u00ed si pou\u017e\u00edv\u00e1n\u00ed testeru tuhosti pro testov\u00e1n\u00ed pap\u00edru podle normy ISO 2493-1"},"content":{"rendered":"

Introduction: Understanding the Role of a Stiffness Tester<\/h2>\n

\"stiffness<\/a>A stiffness tester<\/strong> plays a crucial role in the quality control of paper, paperboard, and similar sheet materials. This instrument measures the bending resistance of a sample, providing insight into the paper\u2019s rigidity, handling performance, and suitability for end-use applications. Accurate stiffness evaluation is essential across packaging, printing, and manufacturing industries.<\/p>\n

In this article, we\u2019ll explore how to perform standardized testing using a stiffness tester in accordance with ISO 2493-1<\/strong>, and how it connects with the tensile strength test for paper<\/strong>, enabling manufacturers to ensure consistency and quality.<\/p>\n

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Why Bending Stiffness Matters in Paper Products<\/h2>\n

Bending stiffness is directly related to product performance. In folding cartons, brochures, or packaging liners, stiffness affects machinability, user experience, and protection ability. When paper is too soft or too rigid, it may fail to meet functional requirements.<\/p>\n

A stiffness tester<\/strong> quantifies this property by applying a defined force to bend a paper sample through a specific angle, then records the resistance. This process allows manufacturers to make informed decisions about raw materials, production processes, and finished goods.<\/p>\n

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Principles of ISO 2493-1<\/a> Testing Method<\/h2>\n

ISO 2493-1 specifies a precise method for measuring bending resistance. The stiffness tester<\/strong> performs this evaluation through controlled deflection under standard conditions. Here’s how the method works:<\/p>\n

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  • A sample is clamped vertically at one end.<\/li>\n
  • A knife edge<\/strong> applies force at a set distance (typically 50 mm or 10 mm).<\/li>\n
  • The clamp rotates through a bending angle of 15\u00b0 \u00b1 0.3\u00b0<\/strong>.<\/li>\n
  • The force required to reach this angle is recorded as the bending resistance<\/strong>.<\/li>\n<\/ul>\n

    This test provides reliable, repeatable results essential for inter-laboratory comparisons and compliance verification.<\/p>\n

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    Test Preparation: Conditioning and Sampling Guidelines<\/h2>\n

    Before using the stiffness tester, samples must be handled according to ISO recommendations:<\/p>\n

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    • Sampling<\/strong>: Follow ISO 186 to select representative samples.<\/li>\n
    • Kondice<\/strong>: Maintain standard temperature and humidity as per ISO 187.<\/li>\n
    • P\u0159\u00edprava vzork\u016f<\/strong>: Cut test pieces to (38.0 \u00b1 0.2) mm in width and at least 80 mm in length for 50 mm bending length.<\/li>\n<\/ul>\n

      Avoid defects like folds or creases, and ensure both machine direction and cross direction are tested for a comprehensive evaluation.<\/p>\n

      \n

      Step-by-Step Testing Procedure<\/h2>\n

      Perform the bending test under these conditions:<\/p>\n

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      1. Insert the sample<\/strong> in the clamp with precise protrusion length (57 \u00b1 3 mm for 50 mm bending).<\/li>\n
      2. Set the angle<\/strong> on the stiffness tester to 15\u00b0.<\/li>\n
      3. Ensure the knife edge<\/strong> contacts the sample without applying prior force.<\/li>\n
      4. Initiate rotation and record the force at the designated angle.<\/li>\n
      5. Discard any results from broken, kinked, or excessively deformed samples.<\/li>\n<\/ol>\n

        P\u0159inejmen\u0161\u00edm 10 valid readings<\/strong> per direction are required for accurate results.<\/p>\n