ISO 6502-2:2025

ISO 6502-2:2025 - Overview

ISO 6502-2:2025 specifies a laboratory method for determining selected vulcanization characteristics of rubber compounds using an oscillating disc curemeter. The standard defines the test principle, required apparatus (dies, biconical disc, torque-measuring system, heating and temperature control), calibration, test-piece preparation, procedural steps, data expression (torque vs time), and reporting requirements. It replaces the 2018 edition and aligns with the general guidance in ISO 6502-1:2025.

Key technical topics and requirements

• Test principle: A biconical disc embedded in a rubber test piece is oscillated; recorded torque as a function of time (M = f(t)) is used to derive vulcanization parameters (cure curve, scorch time, cure rate indices).
• Apparatus and materials:
  • Dies made from non-deforming tool steel, minimum 50 HRC.
  • Die cavity geometry defined in figures; grooves to minimize slippage; temperature sensor ports.
  • Die closure force: 11.0 kN ± 0.5 kN (pneumatic cylinder).
  • Biconical disc manufactured from tool steel (50 HRC), with specified diameters, radii and groove dimensions (see Table 1).
• Disc oscillation and torque:
  • Nominal oscillation frequency 1.7 Hz ± 0.1 Hz (alternative 0.05–2 Hz for specific cases).
  • Maximum angular displacement 1.00° ± 0.02° (about central position; total amplitude 2°) when empty.
  • Linear decrease in oscillation angle with torque: slope 0.05°/N·m ± 0.002°/N·m.
  • Instruments must provide devices to verify amplitude and torque–angle behavior.
• Calibration & accuracy:
  • Calibration schedule and temperature control requirements are specified; normative references include ISO 6502-1:2025 and ISO 18899:2013.
• Procedure and outputs:
  • Sections cover test-piece volume, vulcanization conditions, conditioning, loading, and autographic recording of torque vs time.
  • Output parameters: torque values, times to percentages of full cure, scorch time, cure rate index.

Practical applications and who uses this standard

• Quality control and acceptance testing in rubber manufacturing (tyres, seals, hoses, molded parts).
• R&D laboratories developing new elastomer formulations and vulcanization systems.
• Test and calibration laboratories verifying curemeter performance and compliance.
• Curemeter and test-equipment manufacturers using detailed mechanical and performance specifications for instrument design.
• Regulatory and procurement teams specifying reproducible test methods for contracts and standards compliance.

Related standards

• ISO 6502-1:2025 - Introduction and general principles for curemeters.
• ISO 18899:2013 - Guide to the calibration of test equipment.

Keywords: ISO 6502-2:2025, oscillating disc curemeter, vulcanization characteristics, rubber testing, cure curve, torque measurement, die dimensions, disc oscillation, cure rate index.