The Working Principle and Calibration Method of Electronic Paper Tensile Strength Tester

The electronic paper tensile strength tester is used to evaluate the mechanical properties of materials such as paper under tensile conditions. The specimen is clamped by fixtures and stretched at a constant speed by a servo motor, while sensors measure the tensile force and elongation data, automatically calculating tensile strength and elongation at break. To ensure accuracy, it is essential to regularly calibrate the instrument's force, displacement, and speed systems using tools such as standard force gauges and displacement blocks, with errors generally kept within ±1%. The recommended calibration interval is one year, and daily maintenance should include maintaining a stable environment and keeping the fixtures clean.

Overview

The electronic paper tensile strength tester is a key equipment used to determine the mechanical properties of paper, cardboard and related materials in the tensile state. By measuring the maximum tensile strength and elongation of the specimen under controlled tensile conditions, the tensile strength, elongation at break and other parameters are calculated in combination with the specimen size, which provides a scientific basis for evaluating the mechanical durability and applicability of the material. The instrument is widely used in papermaking, packaging, printing, and material research, and its test results are of great significance for quality control and product development.

How it works:

The instrument is based on electronic sensing and closed-loop control technology to achieve accurate measurements. When working, the fixture holds the specimen of standard size, the upper fixture is driven by a servo motor for uniform stretching, and the lower clamp is connected with a high-precision force value sensor and a displacement sensor. The force sensor detects the tension of the sample in real time, and the displacement sensor synchronously records the change of tensile length. The data acquisition system converts the analog signal into a digital signal and transmits it to the control unit for processing. When the specimen breaks, the system automatically records the maximum force value and the elongation at breakage, and calculates the performance index according to the preset formula.

The formula for calculating tensile strength is:

S=F/ (W×T)

Among them,SIndicates tensile strength (unit: kN/m),Frepresents the maximum tension resistance (unit: N),Wrepresents the width of the specimen (unit: mm),TIndicates the thickness of the specimen (unit: mm). The formula for calculating elongation at break is:

ε= (L-L₀) /L₀× 100%

Among them,εrepresents the elongation at break,Lrepresents the length at break,L₀Indicates the initial gauge length.

Calibration method

To ensure accurate and reliable test data, the instrument needs to be calibrated regularly. Calibration should be carried out according to relevant national or international standards, mainly covering force value system, displacement system and velocity system.

force value calibration

It is performed using a standard force gauge or a certified standard weight. The standard force gauge is installed between the fixtures, and the instrument applies an increasing and decreasing force value sequence to record the displayed value and the standard value of the instrument. The error of calculating the value error and repeatability should generally be controlled within ±1% of the nominal range. The calibration points should cover the common range of measurements, and it is recommended to have no less than 5 points.

Displacement calibration

Standard displacement block or laser displacement measurement device is used. The standard block is placed between the fixtures, and the instrument is driven to move a specific distance, comparing the displacement displayed by the instrument with the standard value. At the same time, check the accuracy of the gauge setting device to ensure that the initial length of the specimen meets the standard requirements. The displacement display error is usually required to be no more than ±0.1mm.

Speed calibration

Use a photoelectric timer or frequency meter to measure the speed at which the beam moves. Set multiple typical speed gears of the instrument, measure the time required to move a fixed distance, and calculate the actual speed. The deviation between the actual speed and the set speed should generally be within ±2%.

Calibration cycle

The recommended calibration interval is 12 months, or adjusted according to the frequency and importance of use. In daily use, attention should be paid to stable environmental conditions to avoid vibration and airflow interference. The fixture should be kept clean to prevent slipping or damaging the specimen. A quick spot check is performed before each test to verify instrument status using standard samples with known performance.

Parameters and requirements

Force value measurement range	Usually 0-500N
force value accuracy	Better than ±1%
Displacement resolution	Up to 0.01mm
Stretch speed range	1-500mm/min
Fixture spacing adjustment range	Usually 50-300mm
Data sampling frequency	Not less than 100Hz

References

GB/T 12914 Determination of tensile strength of paper and paperboard

ISO 1924-2 Determination of tensile strength of paper and paperboard Part 2: Constant speed tensile method

TAPPI T494 Tensile Properties Assay for Paper and Paperboard