Overview
ISO 11093-8:2017 specifies a standardized method for determining the flexural modulus of cylindrical paper and board cores by measuring their natural frequency in the free-free mode of transverse vibration using experimental modal analysis. This test applies to cores with internal diameters ranging from 50 mm to 350 mm, a minimum wall thickness of either 2.0 mm or 0.02 times the internal diameter, and a minimum length eight times the internal diameter. The standard ensures that manufacturers, laboratories, and quality professionals have consistent and accurate techniques to assess the mechanical properties of paper and board cores, essential for product design, quality control, and end-use performance.
Key Topics
- Natural Frequency Measurement: The standard describes how to experimentally measure the first natural frequency of a core suspended in a free-free boundary condition using appropriate equipment.
- Flexural Modulus Calculation: Flexural modulus is determined from the measured frequency, core dimensions, and material properties, which characterize the core’s resistance to bending.
- Core Dimensional Requirements: Specifies permissible size ranges and tolerances for core length, diameter, and wall thickness for accurate testing.
- Sampling and Conditioning: Outlines procedures for sample selection, conditioning based on ISO 11093-2, and moisture assessment per ISO 11093-3.
- Apparatus and Test Setup: Describes the arrangement for supporting and impacting the test piece and the use of a signal analyzer and accelerometer.
- Test Reporting: Requires detailed documentation of test conditions, results, core specifications, and any deviations from the standard.
Applications
The methodology described in ISO 11093-8:2017 has practical applications in:
- Quality Control: Manufacturers of paper and board cores rely on this standard to ensure that their products meet required flexural performance specifications, reducing failure rates during processing and use.
- Product Development: R&D teams use flexural modulus data to design and optimize core structures for specific industrial needs, such as winding, transport, and storage of paper, films, and foils.
- Supplier Evaluation: Consistent testing allows buyers and converters to compare core products from different manufacturers based on reliable performance metrics.
- Certification and Compliance: Laboratories can demonstrate compliance with international standards when certifying product properties for the global market.
- Performance Prediction: The calculation of the rotational speed factor facilitates prediction of resonant behavior, which is critical in high-speed winding operations.
Related Standards
- ISO 11093-1: Sampling methods for paper and board cores.
- ISO 11093-2: Procedures for conditioning test samples.
- ISO 11093-3: Determination of moisture content using the oven drying method.
- ISO 11093-7: Testing of cores - Determination of flexural modulus by the three-point method (alternative to the modal analysis method).
- ISO 11093 Series: Comprehensive suite for testing and evaluating paper and board cores, covering additional mechanical and physical characteristics.
ISO 11093-8:2017 plays a vital role in the paper core testing, quality assurance, and product standardization sectors, supporting efficient, safe, and high-performance use of cylindrical paper and board cores in various industrial applications.
For further details and updates, visit the official ISO website.
Open preview (PDF)Paper and board — Testing of cores — Part 8: Determination of natural frequency and flexural modulus by experimental modal analysis