Overview
ISO 7808:1992 defines a practical method to determine the transfer flow of thermosetting moulding materials during a controlled disc-moulding operation. The procedure quantifies the percentage mass of material that is forced through two apertures in the punch of a disc mould under specified conditions. The method is intended for production control and process monitoring, not as a mandatory material specification.
Key Topics
- Scope and principle: The method measures the mass fraction transferred through punch apertures during a single moulding cycle to assess material flow behaviour under defined moulding conditions.
- Test portion: A 50 g ± 0.5 g sample is specified for each test, ensuring repeatable charge mass for comparative production checks.
- Apparatus requirements: Typical equipment includes a balance (0.1 g resolution), a hydraulic press (≥125 kN) with controlled closure time and pressure control, and a disc mould/punch assembly with defined cavity and recess geometry.
- Procedure essentials: The mould temperature is adjusted to the tabled value for the material under test; moulding pressure is preset (examples include 7, 12 or 19 MPa) chosen so measured transfer flow falls within a practical range; the sample is moulded, cured, cooled and weighed to calculate transfer flow.
- Result expression: Transfer flow is reported as the percentage mass transferred through the punch using the standard formula and the mean of two valid determinations.
- Test report: Required details include reference to ISO 7808, material identification, mould temperature and pressure, flow time and the reported transfer flow percentage.
Applications
This standard is useful for:
- Production control and batch monitoring: Detect changes in processing behaviour between batches or over time.
- Process optimization: Selecting moulding pressure and closure speed to maintain consistent flow without powder displacement.
- Quality assurance: Verifying that material flow remains within expected operating windows before full production runs.
Practical benefits include faster identification of out-of-spec batches, improved reproducibility of moulding operations, and better control of flow-sensitive thermosetting formulations.
Related Standards
- ISO test methods and guidance produced by ISO/TC 61 (Plastics) and relevant subcommittees for thermosetting materials.
- Other ISO standards covering plastics test methods and material property assessment for production and quality control.
For implementation, use ISO 7808:1992 as a production-control tool alongside your company’s internal quality procedures and material data sheets to ensure reliable, repeatable moulding performance.
