BS ISO 13821:2020 pdf free.Corrugated fibreboard – Determination of edgewise crush resistance一Waxed edge method.
The specimens, taken in accordance with ISO 186, shall permit the preparation of test pieces free from converting machine marks. If the test specimens are to be taken from corrugated shipping containers, they should be taken from areas away from score lines, joints, and closures. Specimens should be representative of the materials being tested. For example, if roughly 25 % of a box is printed, roughly 25 % of the specimens should be collected from the printed areas. Specimens should not be taken from obviously damaged areas and/or areas not representative of the container as a whole.The tolerances apply to the mean height and width. These heights typically meet the Euler criteria for pure compression failure in a short column for their respective structures. However, for some thin double-wall board (e.g. EB or EF double-wall), different heights may be required to achieve a pure compression failure in the test specimens. The loading edges shall be cut cleanly and straight. The cleanliness of the cut is judged by inspection without magnification under normal laboratory lighting. Determine that the edges are not frayed and that no loose fibres are visible. The test piece shall be free from converting-machine marks and damage to edges, flutes and test area.Opposite edges shall be parallel and adjacent edges shall be at right angles. Straightness, parallelism and perpendicularity may be judged by the following procedure: Stand two test pieces on their cut edges on a plane surface with two of their faces almost touching. With perfectly flat board, the two adjacent faces should appear flat and parallel to each other over their whole surfaces. If the board is warped, this may not be so, but the test pieces are acceptable if they stand vertically on their bottom edges, if the top cut surfaces appear flat and parallel to each other and  at right angles to the linear surfaces close to the cut, and if the cut ends of the test pieces appear to be in the same plane. It should not be possible to see light under the cut edge of either test piece when a load of about 1 N (equivalent to light finger pressure) is applied to the top edge.BS ISO 13821 pdf download.