Overview
ISO 12192:2011 - Paper and board: Determination of compressive strength - Ring crush method specifies a laboratory method to measure the edgewise compressive strength (ring crush resistance) of paper and paperboard. The method is widely used for components of fibreboard shipping containers and applies to papers and boards with thicknesses from 100 µm to 580 µm. (Note: for specimens below 280 µm, results may include a combination of buckling and pure compression.)
Key topics and technical requirements
- Scope & limitations
- Applicable thickness range: 100 µm–580 µm; bending strain for >580 µm may affect results.
- Below 280 µm, buckling can influence measured values.
- Apparatus
- Cutting device (die cutter or equivalent) to produce clean, parallel edges.
- Test-piece holder with a cylindrical recess (inside diameter 49.30 mm ± 0.05 mm) and removable central disc (6.35 mm ± 0.25 mm thick); annular groove width must be 150–175% of specimen calliper.
- Motor-driven platen-type crush tester (calibrated per ISO 13820) with platen parallelism within 0.025 mm per 100 mm.
- Gloves to avoid contaminating specimens.
- Specimen preparation
- Test pieces typically 12.7 mm wide by 152.4 mm long, free from wrinkles or damage; cut in both machine and cross directions.
- Condition specimens to the standard atmosphere in ISO 187; determine grammage (ISO 536) and thickness (ISO 534) if required.
- Procedure
- Insert a narrow strip into the annular groove, alternating sides facing outward for replicate tests.
- Compress edgewise until onset of failure and record maximum force to the nearest newton.
- Calculations
- Ring crush resistance σ = F / l (kN/m).
- Ring-crush-resistance index X = σ / g (kN·m/g), where g is grammage in g/m².
- Reporting & precision
- Report mean, standard deviation, disc diameter, specimen orientation, conditioning atmosphere, and any deviations. Precision data and repeatability/reproducibility guidance are included.
Applications and users
- Practical for quality control and specification of corrugated board and fibreboard used in packaging and shipping.
- Used by paper and board manufacturers, packaging engineers, independent testing laboratories, and procurement/specification teams to assess in-plane crush resistance that affects container stacking and transit performance.
Related standards
- ISO 186 (sampling), ISO 187 (conditioning), ISO 534 (thickness), ISO 536 (grammage), ISO 13820 (compression-test equipment). These standards are referenced for sample handling, test atmosphere, dimensional measurements and equipment calibration.
Keywords: ISO 12192:2011, ring crush method, ring crush resistance, compressive strength, paper and board, ring-crush-resistance index, fibreboard shipping containers.
