ISO 3927:2017 PDF

Overview

ISO 3927:2017 - "Metallic powders, excluding powders for hardmetals - Determination of compressibility in uniaxial compression" - specifies a laboratory method to measure how metallic powders compact under uniaxial compressive loading in a confining die. The standard applies to most metallic powders used in powder metallurgy but excludes powders for hardmetals. Results are used either at a single specified compacting pressure or across a series of pressures to produce a compressibility curve (density versus compacting pressure).

Key topics and technical requirements

• Principle: Double‑action uniaxial pressing in a confining die; density determined after ejection.
• Test specimens and tooling:
  • Cylindrical compacts: diameter 20–26 mm, height/diameter ratio 0.8–1.0 (example tooling provided).
  • Rectangular compacts: 30 × 12 mm, thickness 5–7 mm (example tooling provided).
  • Mating parts must be fitted and lapped; dies preferably cemented carbide or tool steel.
• Apparatus:
  • Press capable up to ~500 kN, accuracy ±1%, force increase ≤50 kN/s.
  • Scale readable to 0.001 g; micrometer readable to 0.005 mm (dimensions measured to 0.01 mm, mass to 0.01 g).
• Lubrication options:
  • Die wall lubrication (example: zinc stearate solution in acetone).
  • Powder lubrication by admixing solid lubricant (typically 0.5–1.5 % zinc stearate or synthetic wax).
  • Powders with/without lubricant can be tested in dry or lubricated dies per clauses 8.2–8.3.
• Compacting pressures:
  • Recommended series for compressibility curves: 200, 400, 500, 600 and 800 N/mm² (or agreement between parties for single-pressure tests).
• Results and expression:
  • Density ρ = m / V (report to 0.01 g/cm³).
  • Report compressibility as average of three density determinations (to 0.01 g/cm³).
• Precision:
  • Repeatability r = 0.025 g/cm³; reproducibility R = 0.07 g/cm³ (from referenced ASTM data).
• Test report must reference ISO 3927 and include sample ID, test piece type, lubricant details, pressures, results and any deviations.

Applications and users

• Typical users: powder metallurgists, materials engineers, QC laboratories, R&D teams, and manufacturers of pressed metal components.
• Practical uses:
  • Characterizing powder compaction behaviour for process design (pressing parameters, tooling selection).
  • Comparing powder formulations or lubricant blends.
  • Quality control on incoming powders to predict green density and dimensional control.
  • Generating compressibility curves to model sintered part density and performance.

Related standards

• ASTM B331-95 is cited for precision data and offers complementary methodology.
• Prepared by ISO/TC 119 (Powder metallurgy) - useful for locating related powder metallurgy test standards.

Keywords: ISO 3927:2017, metallic powders, compressibility, uniaxial compression, powder metallurgy, compaction, compressibility curve, green density, die lubrication, test method.