ISO 7743:2017

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.