Overview
ISO 1923:1981 is an international standard that specifies methods for the determination of linear dimensions of cellular plastics and rubbers, including both flexible and rigid materials. This standard outlines the selection and characteristics of measuring instruments and procedures for accurately measuring sheets, blocks, or test specimens made of cellular materials. The goal is to ensure consistent and precise measurement of linear dimensions such as thickness, length, and width, using instruments appropriate to the size and type of the material being tested.
Developed jointly by ISO Technical Committees ISO/TC 45 (Rubber and rubber products) and ISO/TC 61 (Plastics), ISO 1923 has been approved by multiple ISO member countries, ensuring wide international acceptance and reliability. This second edition from 1981 updates and replaces the original 1972 edition, refining technical details to enhance measurement accuracy and applicability.
Key Topics
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Scope and Application
The standard covers the measurement of linear dimensions in cellular plastics and rubbers, addressing both flexible and rigid materials. It applies to sheets, blocks, and test specimens, providing specifications tailored to the properties of cellular materials.
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Definition of Linear Dimension
Linear dimension is defined as the shortest distance measured between two distinct parallel surfaces or edges of a specimen, typically between two parallel lines or planes.
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Measuring Equipment and Accuracy Requirements
The selection of measuring instruments is determined by the precision required and the size of the dimensions:
- For precision up to 0.05 mm, a dial micrometer or thickness gauge (Palmer) is recommended, especially for rigid cellular materials.
- For precision up to 0.1 mm, a vernier caliper is suggested, usable for a wider range of materials including flexible specimens.
- For less stringent precision needs (0.5 mm), a metal ruler or tape measure can be employed.
The standard details specific conditions, such as surface area requirements of measuring tips and the pressure applied during measurement to avoid specimen deformation.
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Measurement Procedures
Proper handling and measurement technique are critical. The specimen must maintain its shape during measurement, especially when using rigid base plates. The standard stresses avoiding compression or damage to the cellular material. Multiple measurements at different points on the specimen are recommended to calculate an average dimension reliably.
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Documentation and Reporting
Detailed records must accompany measurement results, including:
- Reference to ISO 1923:1981
- Description of the cellular material
- Measuring instruments used
- Average measured dimensions rounded according to the instrument accuracy
- Any deviations from the standard procedure
Applications
ISO 1923:1981 is essential in industries where precise measurement of cellular plastics and rubber materials is critical for quality control, research, and product development. Typical applications include:
- Manufacturing Quality Assurance
Ensures dimensional conformity of foam sheets, blocks, or molded cellular rubber products.
- Material Testing Laboratories
Provides standardized procedures for material dimension verification in development and certification.
- Product Specification Compliance
Facilitates adherence to customer or regulatory specifications regarding dimension tolerances.
- Research and Development
Enables controlled measurement processes essential for developing new cellular materials and composites.
By applying this standard, stakeholders can improve measurement reliability, reduce errors caused by specimen deformation, and support inter-laboratory consistency.
Related Standards
- ISO 1794 – Previously recommended methods relating to plastics and rubbers, now technically revised and replaced by ISO 1923.
- ISO/TC 45 and ISO/TC 61 Standards – Related standards covering physical testing methods for elastomers and plastics, providing complementary measurement and evaluation techniques.
- ASTM and EN Equivalents – Various regional standards also govern the measurement of cellular materials in plastics and rubbers, often referencing or harmonized with ISO standards.
Keywords: ISO 1923, cellular plastics, cellular rubber, linear dimension measurement, foam material measurement, dial micrometer, vernier caliper, Palmer thickness gauge, cellular material testing, flexible cellular plastics, rigid cellular rubber, measurement standards, international measurement procedures.
