ISO 2493-2:2011 pdf free download – Paper and board – Determination of bending resistance一 Part 2: Taber-type tester.
5 Apparatus
5.1 Bending resistance tester (see Figure 1), consisting of the following components.
5.1.1 Pendulum, P, rotating around a centre-point, CP, on low-friction bearings, carrying a clamp, C, that has two screws for holding and centring the test piece, TP. At the high end, a centre-line, L, is engraved that coincides with the centre of the test piece. At the lower end of the pendulum is a stud, Si, to which weights may be attached and that loads the pendulum at a distance of 100,0 mm ± 0,1 mm from the centre-point. Without added weights, the loading is 10,000 g ± 0,001 g.
5.1.2 Vertical disc, VD, rotating around the centre-point, CP, and driven by a motor, carries two driving arm attachments, DAA, so located as to provide the test piece, TP, with a cantilevered loading length via two driving arms, DA. The bending length (3.4) is 50,0 mm ± 0,1 mm. The driving arms are adjustable by means of screws which enables testing of test pieces of different thicknesses. The ends of the driving arms have rollers as means of transmitting the force to the test piece. It is possible to adjust the length of the arms so that the distance between the test piece and each roller is 0,33 mm ± 0,03 mm.
On the edge of the upper part of the disc, a centre-line mark is engraved. Two reference lines are engraved on the periphery of the vertical disc, VD, at an angular distance of 7,50 and 150 on both sides of the centre-line mark.
A driving mechanism drives the vertical disc, VD, at a nominal constant rate which is allowed to vary between 170° and 210° per minute.
5.1.3 Fixed annular disc, FAD, located around the periphery of the vertical disc, VD. The fixed annular disc has a scale from 0 to 100 on both sides of a centre-line mark, zero. The scale shows the bending moment required to bend the test piece to the right or to the left. (For clarity, only the scale marks 0, 20 and 40 are shown in Figure 1.)
5.1.4 Stand, to support the pendulum, P, the vertical disc, VD, and the fixed annular disc, FAD, equipped with a means for levelling the instrument.
If the tests are being made to evaluate a lot, the sample shall be selected in accordance with ISO 186. If the tests are made on another type of sample, make sure that the test pieces taken are representative of the samples received.
8 Conditioning
Condition the samples of paper or board as specified in ISO 187. Keep them in the conditioning atmosphere throughout the test procedure.
9 Preparation of test pieces
Carry out the preparation of test pieces and the testing in the same conditioning atmosphere as that used to condition the samples.
If the bending resistance index (3.5) is required, determine the grammage in accordance with ISO 536
As required, cut a sufficient number of test pieces. 38,0 mm ± 0,2 mm wide by 70 mm ± 1 mm long, with the length parallel to the machine direction, to enable 5 valid tests to be performed in this direction: and/or cut another set of test pieces with the length parallel to the cross-direction to enable 5 valid tests to be performed in this direction.
Avoid folds, creases, visible cracks or other defects in the area to be tested. If watermarks are present, this shall be noted in the test report.
Highly twisted and curled test pieces may give unreliable results. It is not possible to straighten curled or twisted samples without damaging the material.
10 Procedure
Place a test piece in the clamp, C, with one end approximately level with its top edge and the other end between the rollers at the end of the driving arms, DA.
With the two clamping screws of the clamp, C, align the test piece with the centre-line. L, of the pendulum.
The pressure of the clamping screws may affect the test results. It should be firm enough to hold the test piece, but not so firm as to compress or deform it. The test piece should not be restrained at the free end except by the friction imposed on the surfaces of the free end of the test piece by the driving arms, DA.
Adjust the rollers at the end of the driving arms, DA, so that they are just in contact with the test piece.
Adjust the length of one of the driving arms, DA, so that the distance between the test piece and the roller is 0,33 mm ± 0,03 mm.
NOTE 1 It is not necessary for the pendulum to balance at zero with the undeflected test piece in place Curvature of the test piece will result in a difference between the readings for deflection in the two directions, Readings taken in the two directions are averaged to give the stiffness of the test piece.