8.4.2 Flexing test
8.4.2.1 Apparatus
8.4.2.1.1 Testing device, as illustrated in Figure 45. The test piece shall be guided in such a way that on one side it can be bent at an angle of 90° about a mandrel with a radius of 15 mm.
8.4.2.1.2 Cutting tool, as defined in Figure C.2 of ISO 5423:1992.
8.4.2.1.3 Measuring magnifier, with an accuracy of 0,1 mm.
8.4.2.2 Preparation of the test piece
Take the bottom of the footwear with the insole, separated from the upper, as the test piece.
Define the flexing line in accordance with 8.4.1.2.
Mark a point, for the later insertion of a cut, as follows:
Find the centre of the line AC, and then identify two adjacent cleats that are as close as possible to the centre of the line AC. Mark the sole midway between these cleats (see Figure 46).
8.4.2.3 Procedure
Ensure that the testing device (8.4.2.1.1) is at the neutral flex position (see Figure 45) and clamp the test piece into the device in such a way that the flexing line AC is parallel with the central roller and the cut position marked 8.4.2.2 is directly above the centre roller. If the sole unit is naturally curved, the clamping procedure shall be carried out so that the sole comes close to the centre roller under no load. Manipulate the machine until the test piece is in the maximum flexed, extended or stretched state. Make a single incision at the point marked in 8.4.2.2 with the blade of the cutting tool (8.4.2.1.2) parallel to the flexing line AC. The cutting device shall pass through the full thickness of the outsole and into the insole or equivalent layer. If the product contains a penetration resistant insert, only cut until contact with this is made.
If there are several materials constituting the sole, another incision shall be made, but it is necessary to avoid the cut in a region of 15 mm from the edge of the sole.
Measure the initial length of the cut at the surface of the test piece using the measuring magnifier (8.4.2.1.3).
Carry out 30 000 cycles starting from the maximum flexed, extended or stretched state, with the test piece
undergoing deformation at a constant rate value between 135 cycles/min and 150 cycles/min.
At completion of the 30 000 cycles, the testing device should not be left in the fully flexed position.
After 30 000 cycles, measure the final length of the cut at the surface of the test piece using the measuring magnifier (8.4.2.1.3). The number and dimensions of spontaneous cracks shall be recorded if present.
Cut growth = (final cut length) – (initial cut length).
Flexing Tester for Outsole of Shoes
