Definition
Paper tear strength meter is a special testing equipment used to determine the tear resistance of paper and cardboard. Its measurements are typically expressed in millineuters or Newtons, reflecting the force required for the material to resist tear propagation under pre-made incision conditions. This index is one of the key parameters to evaluate the durability and reliability of paper, and is widely used in the research fields of papermaking, packaging, printing and related materials.
How it works:
The instrument works on the pendulum energy conversion principle. Before testing, the specimen is clamped between the fixed fixture and the movable clamp, and a standard length cut is prefabricated at the edge of the specimen. After releasing the pendulum, its potential energy is converted into kinetic energy, which tears the remaining part of the specimen through a movable clamp. The instrument calculates the tear strength by measuring the remaining swing angle after the pendulum tears the specimen or by recording the maximum force value of the tearing process directly through the sensor. The calculation formula can be expressed as:
E = k * (cosβ - cosα)
where E is the tearing work, k is the instrument constant, α is the starting angle of the pendulum, and β is the maximum swing angle reached after the pendulum is torn.
Measurement method
Standard measurements follow the specifications of the International Organization for Standardization ISO 1974 and the national standard GB/T 455. The operation process includes: preparing specimens of specified sizes, usually multi-layer superposition tests; Hold the specimen symmetrically in the fixture to ensure that the incision is aligned; release the pendulum to complete the tear; Read the instrument values or calculate the final result by calibrating the curve. The test is performed under standard temperature and humidity conditions, and each set of specimens needs to be repeated multiple times to obtain an average value to ensure data representativeness.
Influencing factors
Measurement results are influenced by a variety of factors. The material includes fiber type, length and bonding strength, slurry pulping, filler and additive addition ratio, and paper uniformity and directionality. Process conditions such as drying temperature and pressure can also change the fiber bonding state. In terms of environment, changes in temperature and humidity can cause changes in the moisture content of the paper, which in turn affects the flexibility and bonding of the fibers. Under the test conditions, the specimen pretreatment time, clamping force, incision accuracy and pendulum release consistency all need to be strictly controlled.
Applications:
The instrument has important application value in a variety of industries. In the paper industry, it is used for quality control and product grading in the production process; In the field of packaging, it helps evaluate the resistance to breakage of packaging materials such as containerboard and corrugated paper; In the printing industry, assist in determining the resistance of paper in high-speed printing and subsequent processing; In scientific research institutions, it serves the research on the mechanical properties of new paper-based materials. In addition, relevant standards also use it for the performance evaluation of specialty paper, paper products and similar thin sheet materials.
Equipment selection
When selecting a model, it is necessary to comprehensively consider the measurement range, accuracy level and functional configuration. The measurement range should cover the expected strength value of the material to be measured with a certain margin. The accuracy must meet the requirements of relevant standards for laboratory instruments. In terms of functions, you can pay attention to the data output interface, automatic calibration capability, test mode diversity, and compliance with the latest standard version. User-friendly design, ease of maintenance, and supplier technical support and calibration services are also considerations for long-term use. It is recommended to choose based on actual testing needs, sample characteristics and overall laboratory planning.