Overview
EN ISO 3035:2025 (ISO 3035:2025) specifies a laboratory method to determine the flat crush resistance of corrugated fibreboard used for shipping containers. The standard applies to single-faced and single-wall (double-faced) corrugated fibreboard and excludes double-wall and microflute constructions because the collapse end-point is not clearly observable. Flat crush resistance is reported as the maximum crushing force per unit area (kPa).
Key topics and technical requirements
- Scope & definitions
- Defines flat crush, collapse, and flat crush resistance (force divided by test area).
- Intended for corrugated fibreboard used in container manufacture; not for double-wall or microflute.
- Apparatus
- Motor-driven, fixed-platen flat crush tester calibrated and described per ISO 13820:2021.
- Circular cutting instrument to produce clean, perpendicular test pieces.
- Test specimen sizes
- Common test areas: 5 000 mm² (≈79.8 mm diameter), 6 450 mm² (≈90.6 mm), 10 000 mm² (≈112.8 mm).
- For very high resistance, a smaller area such as 3 220 mm² (≈64.0 mm) may be used.
- Sampling & conditioning
- Sampling per ISO 186; condition specimens in the standard atmosphere per ISO 187.
- Avoid score lines, joints and closures; printed areas may be included but must be reported.
- Procedure
- Test at least 10 specimens in the same conditioned atmosphere.
- Platens approach at 12.5 mm/min ± 0.25 mm/min; record maximum force to the nearest 10 N.
- Flat crush resistance = maximum force / test area (expressed in kPa).
- Precision & reporting
- Clause on precision added in this edition; test report should state sample details, conditioning, sample area and any printed-area inclusion.
Applications and users
- Who uses it
- Packaging manufacturers, quality control laboratories, materials testing labs, packaging designers, procurement teams and standardization bodies.
- Practical uses
- Assessing resistance of corrugated flutes to compressive loading during manufacture, storage and transport.
- Validating material selection and box designs for stacking strength and damage prevention.
- Quality control for production batches and verifying supplier claims.
- Investigating effects of printing or processing damage on local flat crush performance.
Related standards
- ISO 13820:2021 - calibration and description of compression equipment
- ISO 186 - sampling to determine average quality
- ISO 187 - conditioning and standard atmosphere for testing
Keywords: ISO 3035:2025, flat crush resistance, corrugated fibreboard, corrugated board testing, shipping container strength, flat crush tester, packaging testing.
