BS ISO 13821:2020 Corrugated fibreboard – Determination of edgewise crush resistance一Waxed edge method

BS ISO 13821:2020 Corrugated fibreboard – Determination of edgewise crush resistance一Waxed edge method. The following alternative procedure for impregnating the loading edges of test pieces with paraffin is permissible. Place the loading edge on a paraffin-saturated pad, such as paper towelling, heated on a hot plate maintained at 77 °C to 82 °C until the paraffin impregnates the test piece to the desired 6 mm depth. Generally, this method is slower than the dipping method and therefore permits better control of the depth of the paraffin penetration for test pieces in which paraffin migration is rapid. Recondition the test pieces in the standard atmosphere specified in Clause 7. for 2 h to reach equilibrium. 9 Procedure Conduct the tests in the standard atmosphere specified in Clause 7. With the platens of the compression tester conveniently separated, place the test piece on one of its waxed loading edges centrally on the lower platen. Place the two guide blocks (53) on the lower platen, one on each side of the test piece, largest face up, so that the offset ends are in contact with the unwaxed portion of the surface of the test piece. In so doing, the test piece is held perpendicular to the platen surface. Zero the measuring device with these guide blocks in position. Apply a compression force to the test piece using the prescribed loading rate. When the load on the test piece has reached about 50 N, and without altering the platen movement rate, carefully move the guide blocks away from the test piece but do not remove them from the platen. Continue to operate the tester until the test piece fails. Alternatively, the zero may be set before the guide blocks are placed in position on the lower platen. In this case, the guide blocks should be removed from the platen as soon as the test piece becomes securely held. NOTE In using load-measuring devices equipped with a force sensor on the upper plate, the above alternative procedure alleviates the complications associated with zero-setting. Record the maximum load, in newtons, to the nearest 1 N. If the force is calculated from a measured deflection, read the deflection to the nearest 0,01 mm. If either liner does not fail in the unwaxed area of the test piece, the test is not considered valid. Repeat the test on the remaining test pieces until at least 10 valid test...