Overview
ISO 294-2:2018 - Plastics - Injection moulding of test specimens of thermoplastic materials - Part 2: Small tensile bars defines a dedicated four‑cavity (type C) ISO mould and related molding practice for producing small tensile bars (type CW11). The standard specifies the mould layout, critical cavity dimensions, machine considerations and reporting requirements for injection moulding specimens that measure ≥ 60 mm × 10 mm × 3 mm with a thickness tolerance of 3.0 mm ± 0.2 mm.
Key topics and technical requirements
- Mould design: A four‑cavity ISO type C mould with a secondary “double‑T” runner system is specified to produce small tensile bars with the CW11 geometry from ISO 20753. Critical cavity dimensions include a central section width of 3.0–3.1 mm and fillet radius 15–16 mm; cavity depth must produce specimen thickness of 3.0–3.2 mm.
- Injection machine / clamping force: The standard references ISO 294‑1 for machine requirements and gives a recommended minimum clamping force relation tied to maximum injection pressure - for example, a maximum injection pressure of 80 MPa corresponds to a clamping force of 440 kN as stated in the document.
- Injection speed and filling: For the type C mould the recommended injection practice is to select injection speed so that the injection time is comparable to that used with the ISO type A mould. Because the type C critical cross‑sectional area is much smaller (noted in the standard), the effective injection velocity for type C is approximately double that of type A to achieve comparable injection durations.
- Material conditioning and procedure: Material conditioning, moulding steps and reporting follow ISO 294‑1:2017 guidance, with specific additions for the type C mould. Reports must reference ISO 294‑2:2018 and include the data items listed in ISO 294‑1.
Applications
- Producing reproducible small tensile specimens for mechanical testing of thermoplastics.
- Preparing specimens used as “revealing” samples in studies of environmental effects (chemical exposure, heat ageing, weathering) per ISO 11403‑3.
- Quality control, R&D and comparative testing where space- and material‑efficient specimens are required.
Who should use this standard
- Plastics testing laboratories and QA departments
- Injection mould designers and toolmakers producing standardized test moulds
- Polymer R&D teams evaluating mechanical and environmental performance
- Certification bodies and standards engineers specifying test specimen preparation
Related standards
Keywords: ISO 294-2:2018, small tensile bars, injection moulding, thermoplastic materials, type C ISO mould, CW11, ISO 20753, clamping force, injection speed.
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