Overview
ISO 3035:2011, "Corrugated fibreboard - Determination of flat crush resistance", specifies a laboratory method to measure the flat crush resistance of corrugated fibreboard used in shipping containers. The standard applies to single-faced and single-wall (double-faced) corrugated board and defines how to prepare, condition and test specimens so results are comparable across laboratories and production lots. It is widely used for quality control, material specification and performance evaluation of corrugated packaging.
Key topics and technical requirements
- Scope and applicability
- Applies to single-faced and single-wall corrugated fibreboard.
- Not applicable to double-wall (double-double-faced) or microflute board (end-point not clearly defined).
- Sampling and conditioning
- Sampling per ISO 186 and conditioning per ISO 187 to standard atmosphere before testing.
- Apparatus
- Motor-driven platen-type flat crush tester calibrated in accordance with ISO 13820.
- Cutting tool with circularly guided knife to produce clean, perpendicular test pieces.
- Test specimen sizes
- Common circular test areas: ~5 000 mm² (≈79.8 mm diameter), 6 450 mm² (≈90.6 mm), 10 000 mm² (≈112.8 mm); smaller areas (≈3 220 mm², 64.0 mm dia.) may be used when needed.
- Procedure
- Test at least ten valid specimens in the conditioned atmosphere.
- Platens approach at 12.5 mm/min ± 0.25 mm/min; record maximum force to nearest 10 N.
- Reject and retest specimens showing flute leaning; if all lean, report average with a note.
- Result expression
- Compute mean crushing force (F, in kN) and convert to flat crush resistance X (kPa) using X = F × 10^6 / A (A in mm²).
- Report mean and standard deviation of flat crush resistance to the nearest kPa.
- Precision
- Annex A gives repeatability and reproducibility data from interlaboratory programs (TAPPI-CTS, CEPI-CTS), allowing interpretation of expected variability.
Applications and users
- Packaging engineers and designers assessing stacking strength and resistance to flute collapse.
- Quality control and testing laboratories validating corrugated board batches and supplier claims.
- Corrugated board manufacturers for process control and specification compliance.
- Procurement and R&D teams comparing materials, flutes and liners for shipping containers.
- Failure analysis where flat crush contributes to container compression or transit damage.
Related standards
- ISO 13820 - calibration and description of compression-testing equipment.
- ISO 186 - sampling for paper and board.
- ISO 187 - standard atmosphere for conditioning and testing.
Keywords: ISO 3035:2011, flat crush resistance, corrugated fibreboard, flat crush tester, compression testing, shipping containers, stacking strength, corrugated board testing.
