How Is Edge Crush Strength Determined for Corrugated Fibreboard? Standard Method, Instruments and Procedure

This standard sets out the test method for edgewise crush strength in corrugated fibreboard.

It covers single-wall (three-layer), double-wall (five-layer) and triple-wall (seven-layer) corrugated fibreboard for edgewise crush strength measurement.

2 Normative references

When the following documents are cited in this standard, their clauses become part of this standard. The editions listed were valid when the standard was published. Since standards are revised over time, users should examine whether the newest editions below may be used.

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 sample is placed between the two platens of a compression tester. Its flute direction must be perpendicular to the platens. Pressure is applied until the sample collapses, and the maximum pressure it can bear is measured.

4 Test apparatus

4.1 Fixed-platen electronic compression tester

This unit has one fixed platen and one platen that is directly and rigidly driven. The moving platen speed is (12.5±2.5) mm/min. Platen dimensions must match the selected sample size so the sample does not extend past the platens. The platens must also meet these conditions:

a) parallelism error of the platens: no more than 1:1000;

b) lateral movement: no more than 0.05 mm.

4.2 Bending-beam compression tester

This tester uses the beam-bending principle. Its upper and lower platens must satisfy the same requirements as the fixed-platen electronic compression tester. At the moment of collapse, the reading must be within 20%-80% of the instrument's measurable deflection range. Once the platens touch the sample, pressure should rise at (67±13) N/s.

When this instrument is used, the report must state that fact, and the results must not be used for arbitration testing.

4.3 Sample cutting device

Samples may be prepared with a band saw, knife or die, but the cut edges must be smooth, straight and perpendicular to the board surface.

4.4 Guide blocks

Two polished rectangular metal blocks, each 20 mm×20 mm in cross-section and under 100 mm long, hold the sample in place and keep it perpendicular to the platens.

5 Sampling and conditioning of samples

5.1 Sample collection must follow GB 450.

5.2 Samples must be conditioned for temperature and humidity as specified in GB 10739.

6 Sample preparation

Cut rectangular samples so that the flute direction lies along the short side; dimensions are (25±0.5) mm×(100±0.5) mm. Samples must have no indentations, printing marks or damage. At least 10 samples must be cut unless both sides agree otherwise.

7 Test procedure

Cutting and testing must take place under the atmospheric conditions given in 5.2.

Position the sample in the centre of the lower platen so its short side is perpendicular to both platens. Use guide blocks to support it, keeping its end faces perpendicular to the platens; the two guide blocks must be parallel to each other and perpendicular to the sample surface.

Switch on the tester and apply pressure. When pressure nears 50 N, take away the guide blocks and keep loading until the sample collapses. Record the maximum pressure the sample can withstand, rounded to 1 N.

Test the remaining samples in the same way.

8 Expression of results

Edgewise compressive strength is calculated with formula (1) and reported in N/m:

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

F —— maximum pressure, N;

L —— long-side dimension of the sample, mm.

9 Test report

A test report needs to cover the following:

a) the number of this national standard;

b) sample type and specification;

c) the standard applied in the test;

d) atmospheric conditions at the test site;

e) tester model and loading speed;

f) arithmetic mean of the test results;

g) other data that helps clarify the test results.

Source: China Packaging Network (pack.cn), original link: http://news.pack.cn/show-362290.html