Overview - ISO 20753:2023 (Plastics - Test specimens)
ISO 20753:2023 specifies dimensional requirements and designations for test specimens made from plastics intended for moulding or machined from sheets/shaped articles. The standard compiles commonly used specimen types (tensile, bar, small tensile, square and rectangular plates) so laboratories and manufacturers can acquire comparable test data. This third edition harmonises tolerances and clarifies reduced‑scale specimen dimensions, and replaces ISO 20753:2018.
Key technical topics and requirements
- Specified specimen types: Type A (tensile, multipurpose or reduced‑scale), Type B (bar), Type C (small tensile), Type D (square plate), Type F (rectangular plate). Note: absence of a type does not exclude its use.
- Dimensional definitions and symbols: overall length (l), central section length, shoulder radius (r), widths (b), thickness (h) - dimensions and tolerances are defined to ensure inter‑laboratory consistency.
- Preparation methods: requirements for injection moulding, compression moulding and machining of specimens; strict control of preparation conditions to ensure consistent specimen state.
- Surface and marking requirements: surfaces must be free of visible flaws; moulded specimens should have flash removed without damaging surfaces; multipurpose specimens must be suitably marked to identify moulding side or asymmetry.
- Machining rules: guidance on producing bar specimens (e.g., 10 mm bars from central sections), limits on machining tolerances, and precautions to avoid damage to moulded surfaces.
- Reporting and traceability: requirement to report specimen preparation details (see clause on report) to support reproducibility.
- Informative and normative annexes: includes recommended applications for multipurpose specimens and a designation system for specimen naming.
Practical applications and who uses ISO 20753:2023
- Materials test laboratories - for standardised specimen geometry and preparation to obtain reproducible mechanical data (tensile, flexural, anisotropy analysis).
- Plastics manufacturers and compounders - to produce representative test specimens from production materials.
- R&D and quality assurance teams - to compare material grades, process effects (injection vs compression moulding), and to validate formulations.
- Certification bodies and test method developers - to harmonise specimen definitions across test standards and ensure compatibility of results.
Related standards (normative references)
Commonly referenced ISO documents for specimen preparation and moulding:
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