Overview - ISO 7743:2017 (Rubber - Compression stress‑strain properties)
ISO 7743:2017 specifies standardized laboratory methods for determining the compression stress‑strain properties of vulcanized or thermoplastic rubber. The standard covers testing with a standard test piece, a finished product or part of a product and defines four procedures (Methods A–D) to measure compression behavior under controlled conditions. Tests are not suitable for materials that exhibit high set.
Key topics and technical requirements
- Four test procedures
- Method A: Standard test piece A, metal plates lubricated (slip conditions).
- Method B: Standard test piece A, metal plates bonded to the rubber (no slip).
- Method C: Standard test piece B (geometry that minimizes dependence on lubrication/shape).
- Method D: Product or part of a product, plates lubricated (comparative product testing).
- Standard test piece dimensions
- Test piece A: cylinder Ø (29 ± 0.5) mm × height (12.5 ± 0.5) mm.
- Test piece B: cylinder Ø (17.8 ± 0.15) mm × height (25 ± 0.25) mm.
- Apparatus and calibration
- Compression-testing machine per ISO 5893, speed (10 ± 2) mm/min.
- Displacement accuracy requirements (e.g., ±0.02 mm for standard pieces).
- Flat metal plates with a highly polished surface (suggested Ra ≤ 0.4 µm) for lubricated tests; plate preparation varies by method.
- Calibration schedule and procedures specified (see Annex C of the standard).
- Measured properties
- Compression stress, compression strain, compression (secant) modulus and stiffness at 25% compression.
- Test conditions and limits
- Conditioning, temperature control and timing between vulcanization and testing are defined.
- Methods differ in sensitivity to test‑piece shape and lubrication; Annex A explains geometry effects and Annex B gives guidance on extrapolating to non‑standard pieces.
Practical applications and intended users
ISO 7743:2017 is used for:
- Design and qualification of components such as bridge bearings, anti‑vibration mountings, O‑rings and pipe sealing rings.
- Quality control and batch testing in rubber product manufacturing, especially for small parts where hardness testing is impractical.
- Material characterization by R&D laboratories and independent testing labs to obtain compression modulus and stiffness values.
Typical users:
- Materials engineers, test laboratory personnel, OEMs in automotive, aerospace and civil engineering, and rubber product manufacturers.
Related standards
- ISO 5893 - Compression test machine specification.
- ISO 18899:2013 - Guide to calibration of test equipment.
- ISO 23529 - Preparation and conditioning of rubber test pieces.
Keywords: ISO 7743:2017, compression stress‑strain, rubber testing, vulcanized rubber, thermoplastic rubber, compression modulus, stiffness at 25% compression, test piece A, test piece B, method A B C D.
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