Overview
EN ISO 3995:2023 / ISO 3995:2023 - published by CEN/ISO - specifies a standardized test method for determining the green strength of metallic powders. The procedure measures the transverse rupture strength of rectangular compacts (simple beam bending) produced from metal powder to assess green (unsintered) strength either at a specified density or after compaction at a defined pressure. This third edition updates the 1985 edition and supersedes EN 23995:1993.
Key Topics and Technical Requirements
- Scope: Measurement of transverse rupture strength (green strength) of rectangular cross‑section compacts.
- Apparatus: Die (cemented carbide or tool steel), punches, press (up to ~300 kN with ±2% accuracy), balance (±0.01 g), micrometer (±0.01 mm), and a test fixture with hardened support and load cylinders (3.0 mm ±0.1 mm diameter, centres 25.0 mm ±0.2 mm or 25.4 mm ±0.2 mm).
- Sample dimensions: Produce three test pieces 10–13 mm wide, ≥30 mm long, and 5.5–6.5 mm thick; thickness uniformity ±0.1 mm between supports.
- Loading methods: Breaking force measured by a compression testing machine (±2 N) or a loading beam device (lever arrangement) calculated to ±2 N.
- Compacting & lubrication: Procedures for die wall lubrication and powder lubrication (solid lubricants such as zinc stearate or synthetic wax); reporting of lubrication technique and details is mandatory.
- Procedure elements: Cleaning, powder testing conditions (with or without lubricant), compaction (manual or automated sequences allowed), density determination, fracture testing, and expression/reporting of results.
- Tolerances and accuracy: Specific dimensional, force and mounting tolerances defined to ensure reproducible green strength data.
Applications
- Quality control and incoming inspection of metallic powders used in powder metallurgy.
- R&D for powder formulations, pressing/lubrication strategies, and green strength optimization.
- Comparative testing for powder suppliers and component manufacturers to predict handling, ejection, and handling performance before sintering.
- Process validation for compacting tooling and press settings.
Who Uses This Standard
- Powder metallurgy laboratories and testing facilities
- Powder producers and material suppliers
- Component manufacturers (automotive, aerospace, tooling)
- R&D engineers and quality assurance teams involved in compaction and sintering processes
Related Standards and Notes
- Prepared by ISO/TC 119 (Powder metallurgy) in collaboration with CEN; this edition cancels and replaces ISO 3995:1985 and EN 23995:1993.
- The document notes potential patent considerations and follows ISO/CEN adoption procedures.
Keywords: EN ISO 3995:2023, ISO 3995, green strength, metallic powders, transverse rupture, rectangular compacts, powder metallurgy, compaction testing, lubrication, material testing.