The role of the burst strength tester in the testing of cardboard packaging materials.

Rationale

The breakage resistance meter is a special equipment used to determine the breaking strength of packaging materials such as cardboard and corrugated cardboard. The working principle is based on a hydraulic or pneumatic method, where the specimen is clamped between the annular chucks and an increasing pressure is applied at a uniform rate through an elastic diaphragm until the specimen breaks. The maximum pressure value recorded by the instrument is the breakage resistance, usually expressed in kilopascals (kPa) or pound-force per square inch (psi). This process simulates the mechanical behavior of packaging materials under local extrusion and impact during transportation and stacking, which provides a quantitative basis for evaluating the resistance of materials to breakage.

The main function of the breakage resistance meter is to directly evaluate the static rupture resistance of cardboard packaging materials. This index is closely related to the fiber structure, lamination process and raw material quality of cardboard, and can effectively reflect the bearing limit of the material when subjected to uniform external force. Through breakage testing, manufacturers can monitor the stability of the production process, and users can determine whether the material meets specific packaging needs, thereby preventing damage to goods due to packaging breakage. In addition, the breakage resistance data is often combined with edge compression strength, puncture strength and other indicators to form a comprehensive evaluation of the comprehensive performance of packaging materials.

Test methodology

The breakage resistance test follows a number of international and domestic standards to ensure the comparability and accuracy of the test results. Common standards include ISO 2758 (paper), ISO 2759 (paperboard), and GB/T 1539 (determination of breakage resistance of paperboard). These standards detail instrument calibration, specimen preparation, ambient temperature and humidity conditions (typically 23°C, 50% RH), test speed, and method of representing results. During the test, the specimen should be clamped flat to avoid wrinkles or pre-damage, and a sufficient number of specimens should be used for each test to obtain statistically valid data. The consistency of standard methods allows for reliable comparison of data between different laboratories.

Influencing factors

The performance of a breakage meter depends on its accuracy, range, and stability of the control system. Key parameters include pressure resolution, gripping force uniformity, and pressurization rate accuracy. The test results are influenced by a number of factors: the material itself factors such as fiber length, slurry type, humidity content; process factors such as calendering degree and interlayer bonding strength; environmental factors such as temperature and humidity treatment conditions. For example, increased humidity of cardboard usually leads to a decrease in breakage resistance, and the relationship can be approximated by empirical formulas:P = P₀ · e^−kΔm, among themPis the measured breaking resistance,P₀is the breakage resistance under the reference humidity,kis the material coefficient, Δmis the amount of humidity change. Controlling these variables is a prerequisite for ensuring test reproducibility.

Applications:

The breakage resistance meter is widely used in the quality inspection of packaging materials such as corrugated boxes, cardboard, and cardboard, covering the packaging supply chain of various industries such as food, electronics, and consumer goods. The test data is not only used for incoming inspection and production process control, but also provides a basis for packaging design. For example, the safety factor of the packaging can be calculated based on the weight of the contents, the number of stacking layers and the transportation conditions. The following are the reference ranges for breakage resistance of common cardboard types:

It should be noted that in practical application, the qualification judgment should be made according to the requirements of specific product standards, and the above table is only a general reference.

Maintenance and calibration points

In order to ensure the long-term stable operation of the breakage meter, regular maintenance and calibration are required. Routine maintenance includes cleaning the clamping surface, checking diaphragm integrity, and confirming that the hydraulic system is free of leaks. Calibration should be done according to standard procedures, using standard weights or traceable calibrators, and checking the linearity of the time-pressure curve. It is recommended that the calibration interval be no more than 12 months, or immediately after the instrument is moved and served. Standardized maintenance not only extends the life of the instrument, but also ensures that the test data is accurate and meets the requirements of the quality management system.

Epilogue

As a key equipment for the basic performance detection of cardboard packaging materials, the test results of the breakage resistance meter are directly related to the reliability and safety of the packaging. Through standardized testing methods, full awareness of influencing factors, and proper maintenance of instruments, the industry can obtain reliable material performance data to optimize packaging design, control production costs, and improve logistics protection. As the packaging industry's demand for lightweight and sustainability grows, breakage testing will continue to play an important role in material development and quality control.

References

ISO 2759:2014, Board — Determination of bursting strength.

GB/T 1539-2007, Determination of breakage resistance of paperboard.

TAPPI T403 om-15, Bursting strength of paper.

Packaging Engineering Handbook (3rd Edition), China Light Industry Press.