Overview
EN ISO 20482:2013 - "Metallic materials - Sheet and strip - Erichsen cupping test (ISO 20482:2013)" is a CEN-endorsed international test method for assessing the stretch-forming ductility of metallic sheets and strips. The standard defines how to perform the Erichsen cupping test, determining the depth of indentation at the onset of a through crack (the Erichsen cupping index, IE). It applies to sheets and strips with thicknesses from 0.1 mm to 2 mm and widths of 90 mm or greater, with alternate tool dimensions provided for thicker materials or narrower specimens.
Key topics and technical requirements
- Test principle: A spherical punch presses a clamped test piece into a die until a through crack appears; the penetration depth h is recorded.
- Specimen range: Standard thickness 0.1–2 mm, width ≥90 mm. Subscripted tool sizes specified for thicker or narrower specimens.
- Equipment: Die, punch and blank holder with defined dimensions and tolerances (see Table 1 of the standard). Alternatives such as hardened steel balls are permitted.
- Surface & hardness: Working surfaces must be rigid; Vickers hardness ≥ 750 HV30. Punch surface roughness Ra ≤ 0.4 µm.
- Alignment & holding: Punch axis concentricity within 0.1 mm; blank holder force approximately 10 kN.
- Measurement & resolution: Punch movement measured from first contact; gauge division 0.1 mm; thickness measured to 0.01 mm.
- Test conditions: General temperature range 10 °C to 35 °C; controlled tests at (23 ± 5) °C. Punch speed 5–20 mm/min (standard) or 5–10 mm/min for narrow specimens.
- Procedure & reporting: Minimum of three tests; IE is the average of at least three h readings. Test report must reference ISO 20482 and include specimen identity, thickness, lubricant, appearance after rupture (if required), and IE values.
- Lubrication: Graphite grease recommended (calcium soap, refined mineral oil, flake graphite; non-corrosive) - see Annex A.
Applications and users
- Manufacturers and quality engineers in automotive, appliance, aerospace, and general metal forming industries use EN ISO 20482 to:
- Evaluate sheet/strip formability and ductility for stretch-forming processes.
- Compare material lots, coatings or process changes that affect punch/stretch behavior.
- Verify supplier claims for sheet metal used in deep drawing or embossing applications.
- Test laboratories, material inspectors, and standards compliance teams use this standard for consistent, repeatable Erichsen cupping measurements.
Related standards
- ISO 4287 (surface texture/profile method) is referenced for surface roughness definitions.
- Developed under ISO/TC 164 (Mechanical testing of metals), Subcommittee SC 2 (Ductility testing).
Keywords: EN ISO 20482:2013, Erichsen cupping test, metallic materials, sheet and strip, Erichsen cupping index, stretch forming, ductility testing, formability test.