Testing the strength of corrugated cardboard packaging

Requirement

Over the weeks of the COVID-19 lockdown confinement there has been a surge of home deliveries, with even e-commerce giants struggling to fulfil demands and hiring fleets of new workers. Hearing the knock at the door to receive a package provides a small sense of normality and pleasure to many. And it is the humble cardboard box, which is neatly and safely enabling the widespread distribution of goods. Beyond household deliveries, cardboard is also an object serving on the frontline of public health services, enabling mass deliveries of vitally needed medical equipment.

现代生产和运输发生了巨大的变化，我们用来测量包装的力量的测试方法发生了相应的变化。这些天，大部分运费是在托盘上的盒子上完成的，从一个企业提供给另一个企业的商品（B2B）。测试一个盒子的边缘墙体以实现其堆叠强度是最明智的和可靠的衡量标准，盒子在运输过程中垂直重量在垂直重量下将其形式保持良好。

Solution

测试方法

多年来，Mullen Burst测试是瓦楞纸板包装评级的主要行业标准。它需要最小的电路板基础重量。然而，随着现在的再循环含量现在用于瓦楞纸板的制造中，被发现在Mullen突发测试中，相同重量的再循环板并不总是如此良好。尽管这些“再生的委员会的案件仍然具有非常好的压缩和损伤性抵抗品质，所以在边缘压碎测试（ECT）中证明。

The Mullen Burst Test measures the force required to puncture the face of corrugated board and is reported in pounds per square inch (psi) boards are thus rated accordingly e.g. #275. As such, this test was favoured by companies with heavy, awkward-shaped contents requiring protection where the linerboard must not burst outwards. However for companies who simply wish to know the maximum weight a box can withstand, then knowing the overall stacking strength is the primary concern – this is where the Edge Crush Test comes into its own and has become the more common test nowadays.

ECT is a measure of the edgewise compressive strength of corrugated board. It is measured by compressing a predefined section of board on its edge between two rigid platens. This compression is performed perpendicularly to the direction of the flutes until the board collapses and a peak load is reached. This load is reported as force per unit width (lb/in, kN/m etc.). When reported as an ECT value (e.g. 44 ECT), this relates to a minimum strength value and corresponds to pounds per inch width (lb/in). Since the edges and corners of a box are mostly responsible for bearing the load, it gives a good picture of material strength allowing cardboard manufacturers to perform quality control, and box manufacturers to select the most appropriate materials and processes to produce their protective packaging.

A proper ECT-rated corrugated board provides an equivalent level of strength to a Mullen Burst rated board, but typically uses less material. Fewer raw materials, meaning lower energy requirements and reduced pollution, are features associated with properly sized ECT-rated cartons incorporating increasing amounts of recycled content.

标准

There are a number of international standards from various standards authorities, which address the subject of measuring the crush force by the Edge Crush Test.

各种各样的方法都在世界的不同地区。这些可以分为三组，如下所示：

a）在没有任何特殊处理或修改的情况下测试仔细切割矩形试验片的那些（例如，ISO 3037“瓦楞纤维板 - 沿边缘挤压的测定 - 未谐波的边缘法”）。

b) Those in which the edges of the test piece to which the force is applied are waxed, to prevent the test result being influenced by “edge effects“ (e.g. ISO 13821 “Corrugated fibreboard — Determination of edgewise crush resistance — waxed edge method”).

c）测试件边缘未被打蜡但试验片的形状使得长度在加载边缘之间的点处基本上减小，以诱导失败离开这些边缘。（例如FEFCO 8，TAPPI T838和TAPPI T839）

Test equipment

Mecmesin has worked together with both producers and users of corrugated cardboard to supply cost-effective and easy-to-use ECT test systems.

软件控制的压缩测试仪，具有刚性装载柱和精密载荷电池，配有矩形平板。两个独立式导块用于支撑波纹测试样本，从而使其平行于拼盘。测试程序控制测试仪以恒定速度下降，直到达到设定负载，此时可以移除导向块。然后，测试仪进一步继续，直到波纹板塌陷并且软件自动计算所需测量单元（LB / IN，N / MM）中的边缘挤压电阻值。

Bench-top models of ECT Compression Testers are available in capacities of 2.5 kN – 10 kN depending on the range of board to be test