Definition
A paper cardboard thickness gauge is a laboratory testing instrument specifically designed to measure the thickness of paper, cardboard, and its related materials. It mechanically or electronically applies a contact force to the surface of the material under specified pressure conditions and accurately reads the vertical distance between two parallel measuring surfaces. This instrument is one of the basic equipment for evaluating product physical properties and quality control in the fields of papermaking, packaging, printing and material research.
Principle
The core working principle of the thickness gauge is based on contact displacement measurement. The instrument is usually equipped with two parallel and smooth circular measuring surfaces, with the lower measuring surface fixed and the upper measuring surface movable vertically. To measure, the sample is placed between two measuring surfaces, with the upper measuring surface slowly descending at standard pressure until it comes into contact with the sample. At this point, the displacement of the upper measuring surface is converted into a thickness reading by means of a mechanical gauge, electronic sensor or grating system. The standard pressure value is set according to international standards such as ISO 534, GB/T 451.3, etc., and is commonly set at 100 kPa to ensure the comparability and repeatability of measurement results.
Measurement method
The measurement process follows standardized steps to ensure data accuracy. First, the instrument is placed on a stable, vibration-free water surface and calibrated to zero point. When sampling, avoid edges, creases, or areas with obvious defects in the paper sample, and the sample size should be larger than the diameter of the measuring surface. Place the sample flat into the measurement area, slowly lower the upper measuring head, and record the value after the reading stabilizes. Typically, a single sample needs to be measured multiple times at different locations, with the average value taken as the final result. For thicker materials such as cardboard, it is necessary to pay attention to whether the measurement pressure is within the standard range to avoid measurement deviations caused by excessive compression.
Factors that affect measurement
The accuracy of the measurement results is influenced by several factors. The nature of the sample itself, such as surface flatness, elasticity, looseness, and humidity, can cause readings to fluctuate. In environmental conditions, changes in temperature and humidity can cause small changes in material size, so it is recommended to operate under constant temperature and humidity conditions. In terms of instruments, the parallelism and cleanliness of the measuring surface, the accuracy and stability of the applied pressure, and the calibration status of the instrument all directly affect the measured values. The operator's techniques, such as the speed at which the sample is placed and the timing of readings, also need to be controlled through standardized training.
Applications
This instrument is widely used in production, quality inspection and R&D related to paper and cardboard. In the paper industry, it is used to monitor paper uniformity and specification consistency. In the packaging manufacturing industry, thickness is a critical parameter for evaluating the strength, cushioning properties, and printing adaptability of cardboard boxes. The printing industry relies on thickness data to adjust printing pressure and ink transfer effects. In addition, thickness measurement is also one of the basic test items in materials science research, product quality certification, and import and export commodity inspection, providing support for material performance analysis.
Selection considerations
When selecting a model, it is necessary to comprehensively consider the measurement requirements and technical parameters. The measurement range should cover the thickness range of the material to be measured, for example, the required range of thin paper and thick cardboard is different. The resolution and accuracy must meet the requirements of relevant standards for the number of significant bits of data. The measured pressure should comply with the applicable standards, and some instruments support multiple pressure switching to suit different materials. The display mode can be divided into mechanical pointer and digital display, the latter often has a data output function for easy recording. The structural durability, ease of calibration, and compliance with national or international standards are also important aspects of evaluation. Users should choose a model that matches the functions according to the actual application scenario and budget.