ISO 604:2002

Overview

ISO 604:2002 - Plastics - Determination of compressive properties - defines a standardized method to measure the compressive behaviour of plastics under defined conditions. The standard specifies specimen shapes and preferred dimensions, test speeds, apparatus requirements and measurement techniques to determine key properties such as compressive strength, compressive modulus and the compressive stress/strain relationship. It applies mainly to rigid and semi-rigid thermoplastics, thermosets and thermotropic liquid‑crystal polymers, and to short-fibre compounds with fibre lengths ≤ 7.5 mm prior to processing.

Key topics and technical requirements

• Scope & applicability: Intended for moulded, machined or cut specimens from products (right prism, cylinder or tube). Not normally suitable for textile‑fibre reinforced materials, continuous-fibre composites, rigid cellular materials or sandwich structures.
• Specimen dimensions & buckling: Preferred specimen geometries are given; length may be adjusted to avoid buckling. Limits and small-specimen provisions are included (Annex A/B).
• Test speeds: A range of constant crosshead speeds is specified (examples include 1, 2, 5, 10, 20 mm/min) with tolerances; speed selection influences results and must be recorded.
• Apparatus: Requirements for compression plates (hardened steel, flat/parallel surfaces, axial alignment), load indicator accuracy (±1% recommended) and extensometer performance for strain measurement are defined.
• Measured quantities & definitions: Terms such as compressive stress at yield (σy), compressive strength (σM), compressive strain and compressive modulus Ec are formally defined. Modulus determination is based on specified strain intervals.
• Corrections & precision: Procedures for correcting initial curvature of the stress/strain curve and for machine compliance correction are provided (Annex C). Conditioning and test setup precision are emphasized to ensure comparable data.
• Test reporting: Conditioning, specimen preparation, test speed, dimensions and measurement method must be recorded for reproducibility.

Applications and users

• Useful for materials engineers, quality control labs, polymer formulators, test houses and product designers who need standardized compressive property data.
• Typical applications: comparing grades of thermoplastic or thermoset materials, evaluating short‑fibre compound performance, validating material data for structural or component design, and supporting product specifications and datasheets.
• Important where compressive behaviour (crushing, bearing loads, short‑column performance) influences design or regulatory compliance.

Related standards

• ISO 291 - Standard atmospheres for conditioning and testing
• ISO 3167 - Multipurpose test specimens (for specimen extraction)
• ISO 5893 - Test equipment specification (tensile/flexural/compression)
• ISO 10350-1 / ISO 10350-2 - Material data for short-fibre reinforced compounds

Keywords: ISO 604:2002, plastics compressive properties, compressive strength, compressive modulus, compression testing, specimen dimensions, buckling, test speeds, machine compliance.