ISO 6502-2:2018

Overview

ISO 6502-2:2018 specifies a laboratory method for determining selected vulcanization characteristics of rubber compounds using an oscillating disc curemeter. The standard defines the measurement principle-embedding a biconical disc in a rubber test piece, oscillating it through a small rotary amplitude, and recording the torque as a function of time to produce a torque‑time (M = f(t)) vulcanization curve. ISO 6502-2 is part of the ISO 6502 series; introductory material on curemeters appears in ISO 6502‑1.

Key topics and technical requirements

• Principle: Shear strain is applied by an oscillating biconical disc; torque required to oscillate the disc reflects rubber stiffness (shear modulus) during cure.
• Apparatus components:
  • Biconical disc and shaft manufactured from tool steel, minimum 50 HRC hardness.
  • Dies machined from non‑deforming tool steel with specified cavity geometry and grooves to minimize slippage.
  • Die closure using a pneumatic cylinder with force 11.0 kN ± 0.5 kN.
  • Temperature‑controlled aluminium platens with calibrated sensors.
• Disc oscillation:
  • Standard frequency 1.7 Hz ± 0.1 Hz (range 0.05–2 Hz for special purposes).
  • Standard angular displacement 1.00° ± 0.02° about central position (total amplitude 2°); other amplitudes allowed for specific tests.
• Torque measurement and recording:
  • Torque transducer producing signal proportional to torque.
  • Recorder response time ≤ 1 s; accuracy ±1% of torque range.
  • Specified torque ranges: 0–2.5 N·m, 0–5 N·m, 0–10 N·m.
• Temperature control:
  • Die temperature measurement accuracy ±0.1 °C (100–200 °C).
  • Platen control to ±0.3 °C at steady state; die temperature should recover within 3 min after loading.
• Calibration and quality:
  • Apparatus calibration per Annex A and ISO 18899 guidance.
  • Verification of recorder and torque transducer (electronic checks or simulated torque).
• Results and reporting:
  • Extracted parameters include torque values, times to specified cure percentages, scorch time and cure rate index; reporting requirements are specified.

Applications

• Production quality control and acceptance testing of rubber compounds.
• R&D and formulation development to compare cure kinetics and final stiffness.
• Supplier verification, batch-to-batch consistency checks, and troubleshooting vulcanization processes.
• Useful for testing labs, rubber product manufacturers, OEMs, and materials certification bodies needing reproducible curemeter data.

Related standards

• ISO 6502-1:2018 - Introduction to the use of curemeters
• ISO 18899:2013 - Guide to calibration of test equipment

Keywords: ISO 6502-2:2018, oscillating disc curemeter, vulcanization characteristics, curemeter testing, rubber testing, torque‑time curve, cure rate index, scorch time, calibration.