Overview
EN ISO 4492:2017 (ISO 4492:2017) defines a standardized test method for comparing dimensional changes that occur during the compacting and sintering of metallic powders (excluding powders for hardmetals). The method compares a test powder with a reference powder processed under the same conditions and quantifies three types of dimensional change: spring back, sintered dimensional change, and total dimensional change. The standard is intended for use in powder metallurgy quality control, material development and specification.
Key topics and technical requirements
- Purpose: Measure and report dimensional changes associated with compacting and sintering of metallic powders and compare them to a reference powder.
- Three dimensional-change types:
- Spring back (die → green): expansion after ejection from the die.
- Sintered dimensional change (green → sintered): change due to sintering (can be positive or negative).
- Total dimensional change (die → sintered): overall change from die cavity to final sintered part.
- Test pieces and tooling: Standard tooling can produce cylindrical, rectangular or tensile test pieces (tensile tooling per ISO 2740). Tool geometry and tolerances are specified to ensure repeatability.
- Apparatus & measurement:
- Press capable of required compacting pressure/density.
- Sintering furnace reproducing production time–temperature and atmosphere.
- Scale (readable to 0.001 g) and micrometer (readable to 0.005 mm).
- Procedure highlights:
- Use at least three compacts from both test and reference powders processed under identical conditions.
- Measure die, green compact and sintered compact dimensions to 0.005 mm.
- Express dimensional changes as percentages calculated from the measurements; report average of at least three determinations, rounded to 0.01%.
- Reference powder: Selected by agreement between supplier and user, closely matching composition and properties of the test powder.
- Test report: Must include identification of test and reference powders, tooling and part dimensions, green density or compacting pressure, sintering conditions and results.
Applications and users
- Who uses it: powder metallurgy laboratories, material suppliers, component manufacturers, quality control engineers, R&D teams developing sintered components.
- Practical uses:
- Specifying acceptable dimensional behaviour for new powder lots.
- Validating production sintering cycles and tooling designs.
- Comparing candidate powders for dimensional stability in sintered parts.
- Supporting supplier–user agreements on dimensional tolerances and process control.
Related standards
- ISO 2740 - referenced for tensile test-piece tooling (sintered metal materials, excluding hardmetals).
- Other powder metallurgy and sintering standards may be relevant when defining material properties, mechanical testing and sampling procedures.
Keywords: metallic powders, powder metallurgy, compacting, sintering, dimensional changes, spring back, ISO 4492, EN ISO 4492, green compact, sintered dimensional change, total dimensional change.