This International Standard specifies a method for determining the flat crush resistance of corrugated board used in the manufacture of shipping containers. It is applicable to single-faced corrugated board and single-wall corrugated board (double-faced). It is not applicable to double-wall corrugated board (double-double-faced) or micro-fluted corrugated board, as the endpoint of the test is not clearly defined or observable.
The corrugated board samples are conditioned according to ISO 187 and sampled according to ISO 186.
For the measurement of flat crush resistance, the corrugated board samples are placed between the platens of the compression force measuring apparatus. Compression is applied at a constant rate, and the compressive force required to cause permanent deformation is measured.
This International Standard is based on the principle that the flat crush resistance of corrugated board is a measure of its structural integrity. The corrugated board samples are subjected to flat compression at a constant rate, and the compressive force required to cause permanent deformation is measured.
The results are expressed in newtons per meter length (N/m). They shall be accompanied by a statement of precision to give an indication of the reliability of the obtained results.
In accordance with ISO 13820, the apparatus used shall include a compression force measuring device capable of measuring forces up to 5000 N with an accuracy of ± 1%. It shall also include parallel and planar compression platens with a minimum hardness of 60 Shore D.
The following referenced documents are indispensable for the application of this document:
- ISO 186, Paper and board - Sampling to determine average quality
- ISO 187, Paper, board, and pulps - Standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples
- ISO 13820, Paper, board, and corrugated board - Description and calibration of apparatus for compression testing.