Overview
EN ISO 293:2023 - Plastics: Compression moulding of test specimens of thermoplastic materials (ISO 293:2023) specifies general principles and procedures for preparing compression‑moulded test specimens and sheets from thermoplastic materials. It standardizes the main steps (preparation, moulding, cooling and inspection) to obtain reproducible, homogeneous and isotropic specimens for laboratory testing. The document is not applicable to reinforced thermoplastics.
Key topics and technical requirements
- Scope and purpose: Guidance for preparing specimens by compression moulding so test results are reproducible; material‑specific moulding temperature and cooling method are taken from the relevant material standard or agreed between parties.
- Apparatus: Requirements for the moulding press and moulds, including:
- Clamping/pressure: Press must provide a pressure corresponding to at least 12 MPa (clamping force to mould cavity area) and maintain pressure within ±10% during the cycle.
- Platens: Heating capability to at least 320 °C and controlled cooling as defined in the standard; surface temperature uniformity within ±2 °C during heating and ±4 °C during cooling.
- Heating/cooling methods: steam, heat‑conducting fluids, electric elements; cooling normally by fluid channels (e.g., water).
- For quench cooling, use of two presses (one for heating, one for cooling) is specified.
- Material preparation: Drying of granules (including vacuum oven conditions where applicable), preparation of preforms, and preheating times to reach the specified moulding temperature.
- Process timing and temperatures: Definitions and control of moulding temperature, demoulding temperature, preheating time, and moulding time.
- Cooling control: Clarifies average cooling rate and controlled (linear) cooling rate, and standardizes eight different cooling methods (choice depends on polymer type and its crystallization behavior).
- Inspection & reporting: Requirements for inspecting mouldings and recording a specimen preparation report.
Applications and users
- Test laboratories performing mechanical, thermal or rheological testing of thermoplastics.
- Material manufacturers and compounders needing standardized specimen production for quality control and comparability.
- R&D groups validating formulations or processing conditions.
- Standards bodies and conformity assessment organizations coordinating test methods that depend on specimen preparation.
Related standards
- Material‑specific International Standards that specify the required moulding temperature and cooling method for particular thermoplastics.
- Developed by ISO/TC 61 (Plastics) in collaboration with CEN/TC 249; supersedes EN ISO 293:2005.
Keywords: EN ISO 293:2023, ISO 293:2023, compression moulding, thermoplastic materials, test specimens, moulding temperature, cooling rate, moulding press.