ISO 6186:2023

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).