Overview
EN ISO 3923-1:2018 - "Metallic powders - Determination of apparent density - Part 1: Funnel method" - specifies a standardized funnel procedure to determine the apparent density (bulk density in a loose condition) of metallic powders used in powder metallurgy. The method is intended for powders that flow freely through a 2.5 mm orifice and can be adapted for powders that need a 5.0 mm orifice. It defines required apparatus, sampling, test procedure, result calculation and reporting under controlled conditions.
Key topics and technical requirements
- Scope: Apparent density measurement by the funnel method for metallic powders; powders that do not flow through a 5 mm orifice are covered by ISO 3923‑2.
- Accepted funnels:
- Hall funnel: 2.5 mm orifice, 60° cone (ISO 4490).
- Gustavsson funnel: 2.5 mm orifice, 30° cone (ISO 13517).
- Carney funnel: 5.0 mm orifice, 60° cone (Annex A; ASTM B417 dimensions).
- Cup and stand:
- Cylindrical cup volume: 25 cm³ ± 0.03 cm³; internal diameter preferably 28 mm ± 0.5 mm (30 mm ±1 mm acceptable).
- Funnel orifice mounted 25 mm ± 0.5 mm above cup on a vibration‑free stand, coaxial alignment required.
- Apparatus material: Non‑magnetic, corrosion‑resistant metal with polished inner surfaces to avoid distortion and adhesion.
- Balance accuracy: ±0.01 g.
- Sample: Minimum sample volume 100 cm³ to permit three test portions.
- Procedure highlights:
- Fill cup by pouring powder through funnel until overflowing, level with a non‑magnetic straight‑edge without compression.
- If necessary, use 5 mm funnel or initiate flow with a single poke using a 1 mm wire (wire must not enter the cup).
- Tap cup lightly to settle powder for transport and weigh the powder mass.
- Perform three determinations.
- Result expression: Apparent density = mass / 25 cm³; report mean to nearest 0.01 g/cm³ and include range if scatter >1% of mean.
- Precision:
- Repeatability suspect if duplicate tests differ by >0.03 g/cm³ (95% confidence).
- Reproducibility suspect if different labs differ by >0.05 g/cm³ (95% confidence).
- Drying: Powder generally tested as‑received; drying permitted in vacuum or inert gas if oxidation is a concern; do not dry if volatiles present.
Applications and users
- Practical for quality control, incoming inspection and process monitoring in powder metallurgy, metal additive manufacturing, MIM (metal injection molding) and component sintering processes.
- Used by laboratories, manufacturers, material engineers, and procurement teams to assess powder flowability, packing behavior and to specify materials for forming, filling and sintering operations.
Related standards
- ISO 3923-2 - Scott volumeter method for powders that do not flow through a 5 mm orifice.
- ISO 4490 - Hall flowmeter (calibrated funnel) method.
- ISO 13517 - Gustavsson flowmeter method.
- ASTM B417 - Carney funnel dimensions (referenced for Annex A).
