ISO 8307:2018

Overview - ISO 8307:2018 (Ball rebound resilience test)

ISO 8307:2018 specifies a standardized method to determine the resilience by ball rebound of flexible cellular polymeric materials (foams). Commonly called the ball rebound test, the method measures how high a steel ball rebounds after being dropped from a fixed height onto a foam specimen, producing a repeatable percentage resilience value used for quality control, product specification and material comparison.

Key topics and requirements

• Test principle: a steel ball is released without rotation and dropped vertically onto a test piece; rebound height is measured and expressed as a percentage of the drop height.
• Apparatus:
  • Transparent vertical tube, inside diameter 30–65 mm.
  • Steel ball: diameter 16 mm ± 0.5 mm, mass 16.8 g ± 1.5 g.
  • Drop height: 500 mm ± 0.5 mm. Tube must be perfectly vertical and mounted on a rigid, horizontal baseplate.
  • Manual-reading tubes require graduated circles/marks to avoid parallax; automatic systems (electronic timing/light barrier) are permitted if demonstrated equivalent and accurate to ±1% of drop height (±5 mm).
• Test pieces:
  • Plane, parallel surfaces; minimum thickness 50 mm and area at least 100 mm × 100 mm. Thinner pieces may be plied (no adhesive) to reach 50 mm.
  • For moulded products remove top skin.
• Conditioning:
  • Standard: test not less than 72 h after manufacture (with measured exceptions at 16 or 48 h if criteria met).
  • Conditioning atmospheres per ISO 23529: 23 °C ± 2 °C, 50 % RH ± 5 % or 27 °C ± 2 °C, 65 % RH ± 5 %.
• Preflexing:
  • Required for open-cell materials: compress twice to 75–80% thickness at 0.4–6 mm/s and allow recovery 10 min ± 5 min.
• Procedure and results:
  • Test three specimens; take three successive rebounds per specimen (median used). If a value deviates >20% from median, perform two additional drops and use the median of five.
  • Report the median of the three specimen medians as the material’s rebound resilience.

Applications - who uses ISO 8307:2018

• Foam and flexible polymer manufacturers for product specification and R&D
• Third‑party test laboratories and quality‑control departments
• Procurement and specification writers requiring objective resilience data
• Designers evaluating comfort, impact absorption or elasticity of foam materials

Related standards

• ISO 23529 - procedures for preparing and conditioning test pieces (referenced by ISO 8307:2018)

ISO 8307:2018 provides a simple, reproducible foam resilience metric (ball rebound) widely used in materials testing, product development and quality assurance for flexible cellular polymeric materials.