Definition
A grinding fineness plate, also known as a fineness meter or scraper fineness meter, is a physical measurement tool used to assess the degree of particle dispersion in a liquid or slurry material. It determines the grinding fineness of the sample or the distribution range of particle size by scraping the sample flat in a specific trench and observing the scale position of the particles. This instrument plays an important role in quality control in many industrial fields such as coatings, inks, ceramics, cosmetics, and more.
Principle
The measurement of the grinding fineness plate is based on the principle of optical contrast and geometric depth. The main body of the instrument is a metal plate with a precision-machined groove that decreases linearly or stepwise along the length and is marked with a corresponding depth scale. To measure, the sample to be tested is placed at the deeper end of the trench and the sample is scraped through the entire length of the trench at a constant speed and pressure using a matching scraper. As the trench depth gradually becomes shallower, when the particle size is greater than the local trench depth, the particles will be visible there. Observe the scale where the particles begin to appear densely, where the depth value represents the grinding fineness of the sample, usually expressed in microns.
Measurement method
The standard measurement process includes preparation, application, scraping, and interpretation steps. First, make sure that the grinding fineness plate and scraper are clean and dry, stir the sample thoroughly, and place an appropriate amount at the beginning of the groove. The squeegee remains vertical and scrapes the sample towards the shallower trench at a steady speed, creating a uniform film. Within three seconds after scraping, observe the groove area at a certain angle under a standard light source, and read the scale value corresponding to the starting position of the continuous band where the particles are aggregated. To improve accuracy, multiple parallel measurements can be performed to take averages. Operations should follow relevant industry standards, such as ASTM D1210 or GB/T 1724, to ensure comparable results.
Influencing factors
Measurement results are influenced by a variety of factors. In terms of instruments, the machining accuracy of the groove, the calibration status of the scale, and the wear of the scraper will introduce system errors. Sample characteristics such as viscosity and rheological behavior affect the uniformity of scraping and filming. The shape and hardness of the particles may interfere with the appearance of scratch marks. In the operation process, the scraping speed, applied pressure, and the lighting conditions and viewing angles during observation are all key human factors. Ambient temperature and humidity can also indirectly affect readings by changing the sample state. Therefore, standardized operation and regular calibration of instruments are very important to ensure the consistency of measurements.
Application:
Grinding fineness plates are widely used in industrial fields where particle fineness needs to be controlled. In the coatings and inks industry, it is used to evaluate the dispersion quality of pigments and fillers, which directly affects the gloss, color and durability of coatings. Ceramic slurries can be optimized for process parameters with fineness measurements. The cosmetics industry uses it to control the fineness of particles in lotions or foundations. In addition, in the R&D and production of dyes, plastics, abrasives, and other products, this tool is also commonly used to quickly evaluate the dispersion process effect and product quality stability.
Selection
When selecting a grinding fineness plate, consider the measurement range, accuracy requirements, and applicable standards. Common models have a scale range of 0 to 25 microns, 0 to 50 microns, 0 to 100 microns and wider ranges, and the appropriate range should be selected according to the expected fineness of the sample to be tested, usually choosing a model that makes the reading fall in the middle region of the scale to improve resolution. Trench types are available in single-slot and multi-slot designs, and multi-slot plates can be tested simultaneously with multiple samples or parallel tests. In terms of material, quenched stainless steel plate has wear-resistant and anti-corrosion characteristics. In addition, it is necessary to ensure that the instrument meets the relevant standards of the target market or industry, and consider the material and size matching of the matching scraper. Pre-use calibration service and subsequent maintenance support are also reference factors when selecting.