Bursting Strength Test (BST)
Tensile strength is the static breaking strength, measured in kilopascals (Kpa). Tensile strength can be measured by a tensile strength tester.
The bursting strength of kraft paper and cardboard materials meets relevant standards. The bursting strength of the corrugated board can be deduced from the materials used, calculated as the sum of the bursting strengths of each layer of box paperboard multiplied by a coefficient of 0.95, which is unrelated to the corrugation layer.
For example, the bursting strength of single-walled and double-walled corrugated paperboard is calculated as follows:
Single-wall corrugated cardboard (burst strength) BST = (Face Paper BST + Back Paper BST) × 0.95
Corrugated cardboard (bursting strength) BST = (Top paper BST + Flute BST + Liner BST) * 0.95
Because there are gaps between the layers of corrugated cardboard, the buffering ability increases, but it is also more susceptible to being broken layer by layer. Therefore, the result obtained by multiplying the sum of the bursting strength of the layers of box paper by the coefficient of 0.95 in the aforementioned formula aligns with the actual situation. The bursting strength is unrelated to the corrugated layers because: on one hand, the bursting strength of the corrugated layers is much lower than that of the box paperboard; on the other hand, since the bursting strength is a static resistance to rupture, the buffering of the corrugated layers is greater, thereby significantly reducing their bursting strength to the point of negligible consideration.
Edge Crush Test (ECT) and Ring Crush Test (RCT) of Corrugated Fiberboard. The Edge Crush Test measures the edge compression strength of corrugated fiberboard, measured in Newtons per meter (N/m). The Ring Crush Test (RCT) primarily refers to the lateral compression strength of boxboard and corrugated paper, also measured in Newtons per meter (N/m).
The edge crush strength of corrugated board and the ring crush strength of boxboard and corrugated paper are related to RCT, with the calculation formula as follows:
Single-walled cardboard edge compression strength ECT = Face Paper RCT + Back Paper RCT + Corrugated Paper RCT × Fluting Rate
Corrugated cardboard edge crush strength (ECT) = Face paper RCT + Back paper RCT + Flute paper RCT + *Flute paper RCT × respective flute rate + Second flute paper RCT × respective flute rate%
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The edge pressure strength of the corrugated paperboard can be expressed as follows:
A-Type single-wall corrugated cardboard edge crush strength ECT = 1.0 (Face Paper RCT + Back Paper RCT + Corrugated Paper RCT × Flute Rate)
B-flute corrugated cardboard edge crush strength ECT = 1.1 (CT + LT + Corrugated Paper CT × Flute Rate)
Corrugated C-flute edge crush strength ECT = 1.1 (Top Paper RCT + Inside Paper RCT + Flute Paper RCT × Flute Rate)
AB type double wall corrugated cardboard edge compression strength ECT = face paper RCT + 1.1 × liner paper RCT