EN ISO 7808:1998

Overview

EN ISO 7808:1998 / ISO 7808:1992 specifies a standardized test for measuring the transfer flow of thermosetting moulding materials during a defined moulding process. The method determines the percentage mass of material that is forced through two apertures in the punch of a disc mould under controlled conditions. It is intended for production control and process monitoring, not as a mandatory material specification.

Key topics and technical requirements

• Test portion: 50 g ± 0.5 g sample of the moulding material.
• Apparatus
  • Balance accurate to ±0.1 g.
  • Hydraulic press capacity ≥ 125 kN with controlled variable pressure-reducing valve.
  • Disc moulding tool: cavity diameter 90 mm, depth 25 mm ± 5 mm (depth may be increased for bulky materials).
  • Punch recesses: two diametrically opposite recesses, specified depth and profile (dimension tolerance given in the standard).
  • Mould hard-plated (chromium) with tight male/female clearance (≤ 0.05 mm).
• Moulding temperatures: Material-specific nominal temperatures are given in the standard (examples shown for phenolic, polyester, epoxy and diallyl phthalate around the same nominal value in the published table).
• Moulding pressures: Preset options (e.g., 7 MPa ±0.2, 12 MPa ±0.5, 19 MPa ±0.5); choose pressure so measured transfer flow is within 15%–85%.
• Process control:
  • Press closing time (from loading to first gauge pressure) should not exceed 10 s.
  • Closure speed must avoid displacement of powder in the mould.
  • Allow cure, cool, remove extrudate and weigh to nearest 0.1 g.
• Result expression and repeatability:
  • Transfer flow is reported as the percentage mass transferred through the punch (calculated per the formula in the standard).
  • Repeat tests until two consecutive determinations differ by no more than 10% of their mean; report the mean of two valid determinations.
• Test report content: reference to the standard, material identification, mould temperature, pressure, flow time, and transfer flow percentage.

Applications and users

This standard is practical for:

• Quality control and production engineers in thermoset moulding operations.
• Materials technologists and laboratory staff monitoring batch consistency.
• Tooling and process engineers optimizing mould design, moulding pressure and temperature settings.
• Suppliers and processors troubleshooting poor flow, flash or incomplete filling.

Common uses:

• Process control and trend monitoring of transfer flow during production.
• Verifying process changes or raw material lot-to-lot variation.
• Supporting process documentation and internal quality records.

Related standards

• ISO 7808:1992 is the original International Standard; EN ISO 7808:1998 is the European adoption (SIST EN ISO 7808:2000 aligns text in Slovenian publication).
• ICS classification: 83.080.10 (Thermosetting materials).

Keywords: plastics, thermosetting moulding materials, transfer flow, EN ISO 7808, ISO 7808, moulding process, production control, moulding temperature, moulding pressure.