Overview
ISO 6186:2023 specifies laboratory methods for determining the pourability of plastics in powdered and granular form by measuring the flow time through a standard funnel under defined conditions. The standard defines two test methods - Method A (used to derive information about processability) and Method B (intended primarily for process control during manufacture). The methods measure the time a defined mass or volume takes to pass through a funnel and are not necessarily applicable to every powdered or granular plastic.
Key topics and technical requirements
- Principle: Measure flow time for a defined test portion through a funnel of specified geometry and surface finish.
- Funnel specifications:
- Metal funnel (e.g., stainless steel) with polished interior and surface roughness Ra ≈ 0.8 (ISO 21920-2).
- Standard outlet diameters: 10 mm, 15 mm, 25 mm (other diameters may be agreed and require height adjustment to keep the funnel angle).
- Funnel must be earthed to discharge electrostatic charges and fitted with an outlet closing device.
- Apparatus accuracy:
- Stopwatch or timing device accurate to 0.1 s.
- Balance accurate to 0.1 g.
- Conditioning: Test “as received” unless atmosphere affects results. If required, condition samples 24 h at 23 °C ±1 °C and 50 % ±5 % RH per ISO 291.
- Procedure:
- Start tests with d = 10 mm; if the material won’t flow, repeat with 15 mm or 25 mm.
- Method A: Pour 150 g ±1 g into funnel (avoid compaction), remove closing device and time until empty. Three determinations with fresh portions.
- Method B: Overfill funnel, level off, remove closing device and time until empty. Three determinations.
- If electrostatic charge prevents flow, repeat with an agreed antistatic agent and report its use.
- Results and reporting:
- Report mean flow time to the nearest whole second, with method and nozzle (e.g., t = 22 s A10 or B15).
- Describe flow behavior: flows too fast, flows uniformly, flows intermittently, or does not flow.
- Test report must include reference to ISO 6186:2023, material ID, moisture content (if relevant), antistatic agent details, method used, individual and mean results, deviations and test date.
Applications and users
ISO 6186:2023 is used for:
- Material suppliers and compounders to characterize powder/granule flow behavior and processability.
- Production quality control and process engineers for monitoring and controlling dosage, feeding, and handling of plastic powders/granules.
- R&D and testing laboratories troubleshooting flow problems, specifying feed system requirements, or comparing formulations (including masterbatches and recycled powders).
Keywords: ISO 6186:2023, pourability, plastics, powdered and granular, funnel flow test, method A, method B, process control, processability.
Related standards
- ISO 291 - Plastics: standard atmospheres for conditioning and testing.
- ISO 21920-2 - Surface texture: profile terms and parameters (used for funnel surface roughness).
