ISO 13821:2020

Overview

ISO 13821:2020 specifies a standardized test method for determining the edgewise crush resistance (ECT) of corrugated fibreboard using the waxed edge technique. This method measures the compressive strength of corrugated boards by applying force along the flute axis until structural failure occurs. It applies to single-wall, double-wall, and triple-wall corrugated fibreboard, as well as samples taken from converted packaging products such as corrugated shipping cases. The waxed edge method helps eliminate edge effects that can influence test results, providing reliable ECT values that correlate well with the compression strength of finished transport packages.

Key Topics

• Test Scope: The method is valid for various corrugated fibreboard types including single-wall (double-faced), double-wall, and triple-wall configurations. Applicable to both raw boards and finished packaging products.

• Test Principle: A rectangular specimen with flutes oriented perpendicularly to the compression platens is subjected to a compressive force until failure. The loading edges are reinforced with paraffin wax to prevent premature edge failure.

• Sample Preparation: Test pieces are cut with precision cutting equipment ensuring clean, straight, and parallel edges. The samples must be free from machine marks, damage, or distortions and sized according to flute type specifications.

• Waxing Procedure: The loading edges of each test piece are dipped in molten paraffin to a depth of 6 mm and then blotted on heated paper towels. This treatment mitigates edge crushing effects and ensures failure occurs away from edges, improving test consistency.

• Testing Apparatus: Motor-driven compression testing machines following ISO 13820 specifications, along with guide blocks to align and support samples during testing.

• Conditioning and Sampling: Samples must be conditioned in a standard atmosphere prior to testing as per ISO 187. Sampling procedures per ISO 186 are recommended to ensure representative test data from corrugated materials, avoiding damaged or unrepresentative areas.

• Test Execution: The specimen is positioned on waxed edges, compression is applied at a controlled rate, and maximum force sustained is recorded.

• Precision and Reporting: Test precision is supported by comparative data; detailed test reports including specimen size, conditioning, maximum load, and failure observations are required.

Applications

• Quality Control in Packaging: Ensures that corrugated fibreboard and finished shipping cases meet performance requirements during manufacturing and conversion processes.

• Material Specification: Provides manufacturers and end-users with reliable ECT values to specify corrugated grades suitable for intended load-bearing applications.

• Design Validation: Supports structural testing and validation for packaging engineers to optimize board design and strength for transport resilience.

• Standard Compliance: Facilitates compliance with international standards and harmonizes ECT testing methods to improve data comparability globally.

• Durability Assessments: Assists in evaluating the resistance of corrugated boards to compressive forces encountered during handling, storage, and shipping.

Related Standards

• ISO 186: Paper and board - Sampling to determine average quality. Defines how to select representative samples for accurate testing.

• ISO 187: Paper, board and pulps - Standard atmosphere for conditioning and testing. Specifies atmospheric conditions to standardize moisture content and other environmental factors affecting test results.

• ISO 13820: Paper, board and corrugated fibreboard - Description and calibration of compression-testing equipment. Details apparatus requirements for compression strength testing.

By adhering to ISO 13821:2020, manufacturers and testing laboratories ensure consistent, accurate measurement of edgewise crush resistance in corrugated fibreboard, enabling better quality control, reliable packaging design, and improved supply chain performance. The waxed edge method minimizes edge effects seen in alternative test methods, making it a preferred approach for assessing compression strength relevant to end-use packaging applications.