introduction
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ISO 2493-2-1920 – Determination of the bending resistance of paper and paperboard – Part 2: Taber type tester

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This document has been prepared by Technical Committee ISO/TC 6, Paper, Board and Pulp, Sub-Committee SC 2, Test Methods and Quality Specifications for Paper and board.

The second edition cancels and replaces the technically revised first edition (ISO 2493-2:2011). The main changes from the previous edition are as follows:

– Other data reported in Article 12;

– Several editorial updates.

ISO 2493-2-1920 – Determination of the bending resistance of paper and paperboard – Part 2: Taber type tester

A list of all the components in the ISO 2493 series can be found on the ISO website.

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1 Range
This document specifies the steps for measuring the bending resistance of paper and paperboard using the Taber type tester.

This document is used to determine the bending moment required to deflector the free end of a 38 mm wide vertically clampdown specimen by 15° when a load is applied at a 50 mm bending length. For a circuit board that bends 15° and tends to permanently deform, you can use a semi-bending Angle, that is, 7,5 °. The bending resistance is expressed as the bending moment and parameters set by the manufacturer of the Taber tester.

This method is mainly used for paper with high gram weight.

Note that this document does not cover a lower range version of the Taber type instrument with a 10 mm bending length (see References [5]).

ISO 2493-2-1920 – Determination of the bending resistance of paper and paperboard – Part 2: Taber type tester

2 Normative references
The following files are referenced in text in a manner that constitutes part or all of the requirements of this document. For dated references, only the cited version applies. For undated references, a new version of the reference (including any revisions) applies.

ISO 186, Paper and board – sampling to determine average quality

ISO 187, Paper, board and pulp – Standard atmospheres for conditioning and testing and procedures for monitoring sample atmospheres and conditioning

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.1 Bending moment M

The torque required to bend a rectangular specimen clipped at one end is measured under the conditions specified in this document

Note 1: The bending moment is expressed in millinewtonian meters (mN·m).

3.2 Flexural resistance B

The average bending moment (3.1) required to bend a rectangular specimen fixed to one end of the fixture is measured under the conditions specified in this document

Note 1: Flexural resistance is expressed in millinewtonian meters (mN·m).

ISO 2493-2-1920 – Determination of the bending resistance of paper and paperboard – Part 2: Taber type tester

3.3 Bending Angle α

The Angle at which the fixture rotates when it moves from its initial position to the position where the bending resistance (3.2) is measured

Note 1: The bending Angle is 15° or 7.5° (see Article 10).

3.4 Bending Length

The radial distance between the fixture and the position where the force is applied on the sample under test is constant

3.5 Flexural index

Flexural resistance (3.2) divided by gram weight to the third power

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