ISO 4646:2022

Overview

ISO 4646:2022 - Rubber- or plastics-coated fabrics - Low-temperature impact test - specifies a standardized procedure to determine the lowest temperature at which rubber- or plastics-coated fabrics do not exhibit fractures or coating cracks when subjected to a defined impact. The method is intended to predict coated-fabric behaviour at low temperatures only where the deformation and impact conditions match those of the standard. This third edition updates apparatus and heat-transfer medium guidance (e.g., methylcyclohexane for very low temperatures) and replaces the 1989 edition.

Key topics and technical requirements

• Scope and purpose: Determine the lowest non-failing temperature under specified impact conditions for coated fabrics used in low-temperature flexing with or without impact.
• Apparatus: Two common types of impact testers are described. Key components include cantilever-style clamps, a striking arm with a 1.6 mm ± 0.1 mm radius, and dimensional clearances related to specimen thickness. Striker motion must be normal to the specimen surface and positively driven.
• Striker speed: Impact velocity must be between 1.8 m/s and 2.1 m/s during impact and for at least 6 mm of travel after impact; Annex A covers speed calibration for solenoid-actuated testers.
• Heat-transfer medium & temperature control: Use a liquid or gaseous medium that remains fluid and does not affect the material. Recommended media include silicone fluids (down to −60 °C), ethanol (down to −73 °C), and methylcyclohexane cooled with liquid nitrogen (down to −120 °C). Temperature control within ±0.5 °C and thorough circulation are required.
• Test pieces & preparation: Die-punched specimens, typically 6.4 mm ± 0.5 mm wide and with specified clamp lengths (25 mm ± 5 mm free length), thickness measured per ISO 2286‑3. Immerse specimens for 3.0 min ± 0.5 min at test temperature.
• Failure criterion: Any fracture or coating crack visible under a ×5 magnifier after bending the specimen 180° around a 6 mm mandrel.
• Timing and conditioning: Minimum interval after manufacture is 16 hours; conditioning per ISO 2231 (method 1). Maximum and recommended intervals for product/non-product testing are specified.
• Reporting: The test report must reference ISO 4646:2022 and include specimen ID, test temperature, apparatus type, conditioner details, immersion time, number of specimens, striker speed, individual results, thickness, face tested, heat-transfer medium, and test date.

Applications and who uses it

ISO 4646:2022 is used by:

• Coated-fabric manufacturers for R&D and quality control
• Independent test laboratories and conformity assessment bodies
• Procurement and specification writers who require low-temperature performance data
• Designers and engineers selecting coated fabrics for cold‑climate applications where impact and flexing occur

Typical uses include verification of material suitability, comparative material selection, and creating material performance records for low-temperature service conditions.

Related standards

• ISO 2231 - Standard atmospheres for conditioning and testing (referenced for specimen conditioning)
• ISO 2286‑3 - Determination of thickness for rubber- or plastics-coated fabrics (referenced for thickness measurement)

Keywords: ISO 4646:2022, low-temperature impact test, rubber- or plastics-coated fabrics, impact tester, striker speed, heat-transfer medium, test pieces, conditioning, failure criteria.