ISO 1268-4:2005

Overview

ISO 1268-4:2005 - Fibre-reinforced plastics - Methods of producing test plates - Part 4: Moulding of prepregs - specifies a reproducible method to prepare test plates from preimpregnated unidirectional fibres or fabrics (prepregs). The standard covers stacking, compaction, consolidation and curing of prepreg laminates in equipment such as autoclaves, bladder presses, hydraulic presses, pressclaves or vacuum-bag setups. Prepared plates are intended to be machined into test specimens used for material evaluation or quality verification of composite components.

Key Topics and Requirements

• Scope and materials: Applies to all reinforcements and resins, including partially cured thermosetting and thermoplastic prepregs.
• Conditioning: Materials must be conditioned in standard atmospheres (see ISO 291) before lay-up; thermoset prepregs should be cured within 6 hours after conditioning unless otherwise specified.
• Lay-up and stacking: Cut and stack plies to the required sequence and orientation; Annex A provides a stacking designation system. Insert a thermocouple into the stack for temperature control.
• Equipment and tooling: Defines acceptable apparatus - presses, mould plates (flatness within 0.05 mm), autoclaves, ventilated ovens, vacuum pumps (capable of 0.08 MPa vacuum or better), and compressed-air supply (approx. 0.7 MPa ± 2%).
• Auxiliary materials: Release film, perforated release film, pressure blanket, breather and absorbent layers, rubber seals and metal edge strips are specified to control resin bleed and surface finish.
• Process control: Temperature control with a minimum heat-up rate of 3 °C/min; curing temperature must be held within specified limits and surface variation kept within ±2 °C of the control thermocouple. Pressure and force-time profiles must be accurate to ±5%.
• Post-process handling and measurement: Cool without distortion, mark fibre orientation, trim at least 10 mm from plate edges, and perform dimensional/weight checks (ruler accuracy 0.5 mm, micrometer 0.01 mm, balance 0.01 g) as part of plate quality determination.
• Documentation: Record curing cycle, stack sequence, equipment, measurements and other data in a test plate preparation report.

Applications and Users

• Composite materials laboratories producing standardized test specimens for mechanical, thermal or chemical testing.
• R&D teams developing prepreg systems, lay-ups and cure cycles.
• Aerospace, automotive and sporting-goods manufacturers implementing quality control for prepreg laminates.
• Certification bodies and test houses verifying material conformance and production consistency.

ISO 1268-4:2005 supports reproducible prepreg moulding practices and helps ensure that test plates accurately reflect material properties for reliable testing and quality assurance.

Related standards

• ISO 1268-1 (General conditions)
• ISO 291 (Standard atmospheres for conditioning and testing)
• ISO 2818 (Preparation of test specimens by machining)
• ISO 1172, ISO 1183, ISO 7822 (referenced test and measurement methods)