Overview - EN ISO 3927:2017 (Metallic powders, compressibility in uniaxial compression)
EN ISO 3927:2017 (ISO 3927:2017) defines a standardized laboratory method to measure the compressibility of metallic powders (excluding powders for hardmetals) when compacted by uniaxial compression in a confining die. The document specifies the principle, required apparatus, sampling, test procedure (cleaning, lubrication, compaction and ejection), and expression of results so that density as a function of compacting pressure - the compressibility curve - can be determined reproducibly.
Key topics and technical requirements
- Scope limitation: Not applicable to powders for hardmetals.
- Principle: Double‑action uniaxial pressing in a confining die; density of ejected compacts gives compressibility.
- Tooling and test pieces:
- Cylindrical compacts: diameter 20–26 mm, height/diameter ratio 0.8–1.
- Rectangular compacts: 30 × 12 mm, thickness 5–7 mm. Tooling examples and punch tolerances are included.
- Apparatus accuracy: Press capable up to ≈500 kN with ±1% accuracy; force increase rate ≤ 50 kN/s.
- Measurement precision: Balance readable to 0.001 g; micrometer readable to 0.005 mm.
- Lubrication options: die wall lubrication (e.g., lubricant solution) or powder lubrication (0.5–1.5% solid lubricant); also testing in dry die depending on powder/lubricant content.
- Compacting pressures (recommended): 200, 400, 500, 600 and 800 N/mm² for producing a compressibility curve. Single-pressure testing permitted by agreement.
- Results expression: Compressibility symbol ρ and notation for pressure-specific values (e.g., ρp(400)).
- Procedure details: cleaning with volatile solvent, uniform filling, preliminary force, controlled final force, ejection and measurement of mass and dimensions.
Applications and users
- Quality control and acceptance testing in powder metallurgy manufacturing.
- Materials development and R&D for metal powders (sintering feedstocks, MIM, PM components).
- Suppliers characterizing powder flow/compression behavior for product datasheets.
- Laboratories performing inter-lab comparisons and material certification where standardized compressibility data are required.
Related standards and status
- International standard prepared by ISO/TC 119 (Powder metallurgy), Subcommittee SC 2.
- This edition (2017) supersedes EN ISO 3927:2011 and is published as EN ISO 3927:2017 by CEN.
Keywords: EN ISO 3927:2017, ISO 3927:2017, metallic powders, compressibility, uniaxial compression, powder metallurgy, compressibility curve, die and punches, compacting pressures.