Testing Quality of Corrugated Box

Bursting Strength

The combined tensile strength and stretch of a material as measured by the ability of the material to resist rupture when pressure is applied under specified conditions to one of its sides by an instrument used for testing the property. Testing for the bursting stength of paper is a very common procedure, although its value in determining the potential permanence or durability of paper is suspect.

Ring Crush Test

Ring Crush is a traditional test of linerboard and corrugating medium strength. Ring crush measures compression resistance, and this compression strength is considered to relate to the eventual compression strength of combined board made from the component. Linerboard called high strength or high performance linerboard is board that is able to achieve a specified minimum ring crush at basis weights that are lower than traditional basis weights.

Concora Crush Test

The Concora Crush Tester performs a series of tests to determine the rigidity and crush resistance of corrugated material. It is used in conjunction with the Concora Liner Tester. The first test measures the flat crushing resistance of a laboratory-fluted corrugated material. The second test determines the edgewise strength, parallel to the flutes, of a short column of single-, double-, or triple-wall corrugated board. The third test evaluates the ability of corrugated material to contribute to the compression strength of a corrugated box by measuring the edgewise compression strength of a laboratory-fluted strip of corrugated material in a direction parallel to the fluted tips.

Standard specifications of Kraft Liner board and Corrugating Medium are
shown in the tables below

Type of Paper Grade Basic Weight (gsm) Min Bursting Strength (kg/cm2) Min Ring Crush C.D.
(kg/6 in.) (kg/cm)
Kraft Linerboard KS 170 3.9 19.37 1.27
KA 125 3.5 13.26 0.87
150 4.2 18.35 1.20
185 5.1 22.43 1.47
230 6.4 28.55 1.87
KI 125 2.6 10.71 0.70
150 3.1 14.28 0.94
185 3.8 17.85 1.17
Type of Paper Grade Basic Weight (gsm) Min Bursting Strength (kg/cm2) Min Ring Crush C.D.
(kg/6 in.) (kg/cm)
Corrugating Medium CA 105 16.31 8.67 0.57
125 19.37 12.24 0.80

RemarkThe figures shown in the tables can be varied due to the raw materials of paper manufacturing and the paper quality of each supplier. According to the figures, we can notice that the strongest paper grade is KA, KS, and KI respectively. Moreover, the strength of paper is also counted on the basic weight.