Definition
Cardboard puncture strength tester is a special testing equipment used to determine the ability of cardboard materials to resist the impact penetration of sharp objects. The instrument quantitatively evaluates the puncture resistance of materials by simulating sudden puncture behavior that may be encountered during transportation, warehousing, or use. Its measurement results are usually expressed in energy units, which is one of the key indicators for the evaluation of mechanical properties of packaging materials.
How it works:
The core working principle of the instrument is based on the law of energy conversion and conservation. During the test, a swing arm fitted with a specific shape of a poke head was lifted to a fixed height to store a certain amount of potential energy. When released, the swing arm falls freely, and the potential energy is converted into kinetic energy, which pierces the head vertically and penetrates the specimen fixed to the fixture. The instrument calculates the energy consumed during the penetration process by measuring the height of the remaining swing after the piercing head penetrates the specimen, which is the puncture intensity. Its basic energy relationship can be expressed as:
E = m * g * (h1 - h2)
where E represents the puncture strength, m is the mass of the swing arm, g is the acceleration of gravity, h1is the initial height of the swing arm, h2The height raised by the swing arm after penetration.
Measurement method
The measurement process is subject to standardized operating procedures. First, the specimen is clamped flat in the instrument's clamping device to ensure that it is in a tight and wrinkle-free state. Subsequently, according to the estimated strength of the specimen, the appropriate pendulum weight and measurement range are selected. The swing arm is raised and locked in the initial position, and the release mechanism allows the piercing head to fall freely, completing the impact penetration of the specimen. The pointer or sensor records the maximum height at which the swing arm swings after penetrating the specimen, and the puncture strength value is read out or calculated directly via a dial or digital display system. Usually, the same specimen needs to be tested multiple times at different parts, with the arithmetic average as the final result.
Influencing factors
The accuracy of test results is influenced by multiple factors. In terms of specimens, the quantification, thickness, fiber structure and orientation, moisture content and pretreatment environment (temperature and humidity) of the material will significantly change its puncture resistance. In terms of instruments, the geometry and sharpness of the puncture head, the frictional resistance of the swing arm, the sensitivity of the release mechanism, and the clamping force of the fixture on the specimen are key to ensuring test repeatability. In terms of operation, whether the specimen is clamped flat, whether there is no initial thrust on the release of the swing arm, and whether the instrument is placed horizontally are all operational variables that need to be controlled.
Applications:
This instrument is widely used in the quality assessment of packaging products based on cardboard. In the production and use of corrugated boxes, heavy paper bags, paper corner guards and other transportation packaging, puncture strength is an important basis to measure its ability to protect the contents from accidental puncture damage. In addition, the test can also provide valuable mechanical reference data in quality control in areas such as cardboard for special industries and plates for construction. Relevant test methods are an important part of packaging material standards in many countries and regions.
Equipment selection considerations
When selecting equipment, it is necessary to comprehensively consider the testing needs and technical parameters. First of all, the standard system to be followed (such as ISO, GB, TAPPI, etc.) should be clarified, and different standards have specific regulations on the size of the puncture head and the energy range of the swing arm. Secondly, according to the strength range of the material to be measured, select instruments with corresponding range and index values to ensure measurement accuracy. The structural rigidity of the instrument, the low friction characteristics of the pendulum bearing, and the durability and convenience of the fixture are the basis for ensuring long-term stable operation. In addition, the data reading method (pointer type or digital type) and whether it has data output function can be selected according to the needs of laboratory information management. Calibration ease of equipment and after-sales technical support are also considerations for sustainable use.