Method for Determining the Edgewise Crush Strength of Corrugated Fibreboard

This standard specifies the method for determining the edgewise compressive strength of corrugated fibreboard.

This standard applies to the determination of the edgewise compressive strength of single-wall (three-layer), double-wall (five-layer) and triple-wall (seven-layer) corrugated fibreboard.

2 Normative references

The provisions contained in the following standards constitute provisions of this standard through reference in this standard. At the time of publication of this standard, the versions shown were all valid. All standards are subject to revision, and parties using this standard should investigate the possibility of applying the new versions of the following standards.

GB 450-89 Sampling of paper and paperboard specimens

GB 10739-89 Standard atmosphere for conditioning and testing of pulp, paper and paperboard specimens

3 Test principle

A rectangular corrugated fibreboard specimen is placed between the two platens of a compression tester with the corrugation direction of the specimen perpendicular to the two platens, and pressure is then applied to the specimen until it collapses. The greatest pressure that each specimen can withstand is determined.

4 Test apparatus

4.1 Fixed-platen electronic compression tester

This compression tester is composed of one fixed platen and another directly rigidly driven platen, and the moving platen travels at a speed of (12.5±2.5) mm/min. The dimensions of the platens shall accommodate the selected specimen size so that the specimen does not extend beyond the platens. The platens shall also meet the following requirements:

a) the parallelism deviation of the platens is not greater than 1:1000;

b) lateral displacement does not exceed 0.05 mm.

4.2 Bending-beam compression tester

This compression tester operates on the principle of beam bending, and the requirements for its upper and lower platens are the same as those for the fixed-platen electronic compression tester. During testing, the reading at the moment of collapse shall fall within the range of 20%-80% of the deflection range the instrument is capable of measuring; when the platens begin to contact the specimen, the rate of increase of platen pressure shall be (67±13) N/s.

When this type of instrument is used for testing, it shall be noted in the report, and it shall not be used for arbitration testing.

4.3 Specimen cutting device

A band saw or a knife may be used, or a die may be used to prepare specimens, but the edges cut must be smooth, straight and perpendicular to the surface of the board.

4.4 Guide blocks

Two smoothly ground rectangular metal blocks with a cross-section of 20 mm×20 mm and a length of less than 100 mm; the guide blocks are used to support the specimen and keep it perpendicular to the platens.

5 Sampling and conditioning of specimens

5.1 Specimens shall be sampled in accordance with the provisions of GB 450.

5.2 Specimens shall be conditioned for temperature and humidity in accordance with the provisions of GB 10739.

6 Preparation of specimens

Rectangular specimens shall be cut with the corrugation direction along the short side, with dimensions of (25±0.5) mm×(100±0.5) mm. The specimens shall be free from indentations, printing marks and damage. Unless otherwise agreed by both parties, at least 10 specimens shall be cut.

7 Test procedure

Specimen cutting and testing shall be carried out under the atmospheric conditions specified in 5.2.

Place the specimen in the exact center of the lower platen so that the short side of the specimen is perpendicular to the two platens, then support the specimen with the guide blocks so that its end faces are perpendicular to the two platens, with the two guide blocks parallel to each other and perpendicular to the surface of the specimen.

Start the tester and apply pressure. When the pressure approaches 50 N, remove the guide blocks and continue until the specimen collapses. Record the greatest pressure the specimen can withstand, to 1 N.

Test the remaining specimens according to the above procedure.

8 Expression of results

The edgewise compressive strength shall be calculated according to formula (1) and expressed in N/m:

Where: R —— edgewise compressive strength, N/m;

F —— greatest pressure, N;

L —— dimension of the long side of the specimen, mm.

9 Test report

The test report shall include the following:

a) the number of this national standard;

b) the type and specification of the sample;

c) the standard used for the test;

d) the atmospheric conditions at the test site;

e) the model of the test instrument used and the loading rate;

f) the arithmetic mean of the test results;

g) other information helpful in explaining the test results.

——This article is reprinted from China Packaging Network (pack.cn), original link: http://news.pack.cn/show-362290.html