Case Strength

Case Strength

Case Strength

Choosing the right corrugated case can be a confusing task. There are varying thicknesses (single wall, double wall, triple wall), several different flute types (A, B, C, E, F, etc.), and a wide variety of papers that can be used in corrugated construction, including paper with post-consumer recycled content. In addition there is a choice of case styles and different manufacturing processes such as RSC or die-cut boxes. All of these details impact the strength and durability of the case.

 

Types of Flutes
Flutes come in several standard shapes or flute profiles (A, B, C, E, F, etc.). The most common are “B-flute” (used for die-cut boxes) and “C-flute” (used for RSC’s). B-flute is compressed and appears thinner. It is made with more paper to provide stronger side wall protection from blows and punctures. C-flute is taller, with more air space, but offers enhanced stacking strength. E-flute is excellent for graphic reproduction.

Determining Strength
There are currently two tests used throughout the corrugated industry
to determine strength. Historically the industry standard has been the Bursting (Mullen) Test, measuring the force required to rupture or puncture the face of corrugated board. This force is indirectly related to a carton’s ability to withstand forces to make it suitable to contain and protect a product during shipment. Bursting strength is reported in pounds (for example, 200# test).A new standard that has achieved acceptance is the Edge Crush Test (ECT). This is a performance test related to the stacking strength of a case. It is measured by compressing a small segment of board on edge between two rigid plates perpendicular to the direction of the
flutes until a peak load is established. This is measured in pounds
per inch of load bearing edge (lb/in), and reported as an ECT value.
(for example, 32 ECT).

Corrugated Board Strength Equivalencies: Single Wall Corrugated
Bursting Test Minimum Edge Crush Test Maximum Suggested Loading Limit
125# 23 ECT 20 lbs.
150# 26 ECT 35 lbs.
175# 29 ECT 50 lbs.
200# 32 ECT 65 lbs.
275# 44 ECT 95 lbs.
350# 55 ECT 120 lbs.
Corrugated Board Strength Equivalencies: Double Wall Corrugated
Bursting Test Minimum Edge Crush Test Maximum Suggested Loading Limit
200# 42 ECT 80 lbs.
275# 48 ECT 100 lbs.
350# 51 ECT 120 lbs.
400# 61 ECT 140 lbs.
500# 71 ECT 160 lbs.
600# 82 ECT 180 lbs.
Considering all the variables it is likely that you will consult a reliable corrugated supplier to determine the quality and strength most suitable for your needs.
Case Strength