ISO 3384-2:2019

Overview

ISO 3384-2:2019 specifies laboratory methods for measuring stress relaxation in compression of vulcanized or thermoplastic rubber when subjected to repeated temperature changes. The document defines two temperature-cycling test methods that measure the decrease in counterforce (sealing force) exerted by a rubber test piece held at constant deformation. Results are intended to assess ageing, sealing performance at low temperature and the effects of thermal stress.

Key topics and requirements

• Two test methods
  • Method A: Cycled at intervals between a high temperature (ageing) and a low temperature for checking sealing force at low temperature.
  • Method B: Continuous cycling between high and low temperature to introduce thermal stress during the test.
• Test pieces
  • Two shapes: cylindrical test pieces and ring test pieces.
  • Comparison of results is valid only for test pieces of similar size and shape.
  • Ring test pieces recommended for stress-relaxation testing in liquid environments.
• Apparatus and measurement
  • Compression device with two parallel, highly polished plates (chromium-plated steel, stainless steel or corrosion‑resistant material).
  • Plates must be rigid (bending ≤ 0.01 mm) and gap variation ≤ ±0.1 mm when assembled without a test piece.
  • Surface finish typically not worse than Ra 0.4 µm.
  • Plates for ring pieces require centre holes (≥ 2 mm) to allow fluid equalization.
  • Counterforce measured by a continuous-measurement system with accuracy of 1%.
  • Deformation must be maintained within ±0.01 mm during the test (mechanical or mathematical correction allowed).
• Other procedural aspects
  • Calibration, conditioning, test duration, temperature selection and immersion liquids are specified; follow related ISO references for ovens and calibration practice.

Applications and users

• Practical for assessing sealing force, durability and ageing of rubber seals, gaskets, hoses and vibration-isolation parts used in environments with temperature cycling (e.g., automotive, aerospace, industrial seals).
• Intended users: materials/test laboratories, rubber compound and component manufacturers, OEM quality and design engineers, certification bodies evaluating low-temperature sealing performance.
• Helps predict field performance where thermal contraction/crystallization at low temperature can reduce sealing effectiveness (examples cited include cycling between −40 °C and 150 °C).

Related standards

• ISO 3384-1 (series): related procedures for stress relaxation
• ISO 188: accelerated ageing and heat resistance (oven requirements)
• ISO 23529: test piece preparation and conditioning
• ISO 18899: guide to calibration of test equipment

Keywords: ISO 3384-2:2019, stress relaxation in compression, temperature cycling, vulcanized rubber, thermoplastic rubber, sealing force, continuous measurement, ring test pieces.