Definition
The fineness plate is a physical inspection tool used to evaluate the particle size distribution and dispersion in liquid or slurry materials. It is typically constructed from a metal plate with precision notches, and the depth of the notch decreases evenly from one end to the other, forming a gradient. In chemical, coating, ink, ceramics and food industries, fineness plates are widely used to quickly judge the grinding fineness or particle aggregation state of products, and are common instruments in the process of production quality control and research and development.
Principle
The measurement of fineness plates is based on the scraper principle. The sample to be tested is placed at the deepest end of the groove and scraped over the plate surface at a constant speed and pressure using a special scraper. Due to continuous variation in the groove depth, particles in the sample larger than the local groove depth will be dragged out or exposed by the scraper. Observe the depth of the groove where the particles begin to appear significantly, and the scale value corresponding to this position reflects the maximum particle size or dispersion fineness of the sample. The theoretical basis can be simplified as follows: only when the diameter of the particles is less than or equal to the depth of the groove can they be fully embedded in the groove without being disturbed by the scraper.
Measurement method
Make sure the fineness plate and scraper are clean and dry before measuring. Drop the sample at the deeper end of the notch, and the dosage should be slightly more than filling the notch. Hold the scraper perpendicular to the plate surface and scrape at a uniform speed towards the shallow end of the groove, so that the sample is laid flat in the entire notch area. Immediately after scraping, tilt the board surface to the appropriate angle and observe the location of the particles under the specified lighting conditions. The reading is the fineness value, usually measured in microns. Operations should be completed within standard times to avoid sample volatilization or sedimentation affecting the results.
Influencing factors
The accuracy of the measurement results is influenced by several factors. The properties of the sample itself, such as viscosity, volatility, and leveling, can affect the distribution state after scraping. Consistency in handling techniques is critical, and changes in scraping speed, pressure, and angle can lead to biased readings. Environmental conditions such as temperature and humidity may change the properties of the sample or cause condensation on the plate surface. The maintenance status of the fineness plate cannot be ignored, as worn, scratched or contaminated grooves can directly affect the depth of the groove. In addition, the lighting conditions during observation and the observer's judgment experience also play a role in the reading.
Application
Fineness plates are mainly used in industrial fields where particle fineness needs to be controlled. In the coatings and inks industry, it is used to detect the dispersion of pigments and fillers to ensure product color, gloss, and stability. Ceramic slurry can be used to evaluate the grinding effect of raw materials through the fineness plate, which affects the final sintering quality. In the food industry, the taste and graininess of certain sauces and chocolates can be monitored by similar principles. In addition, in emerging fields such as battery paste and cosmetics, fineness plates are also used as a means of rapid quality control. Its advantages are ease of operation, low cost and immediate feedback for on-site monitoring of production lines.
Selection
There are several technical parameters to consider when selecting a fineness plate. The range is the primary factor, and the plate type should be selected according to the expected fineness range of the sample to be tested, with common scales ranging from 0 to 100 microns. The grooving accuracy is related to the material, and the stainless steel plate has good wear resistance and is suitable for long-term use. Groove designs, such as single-slot or multi-slot constructions, can accommodate different throughput needs. The material and size of the matching scraper should match the fineness plate to ensure a flat contact surface. Additionally, refer to relevant industry standards, such as ASTM D1210 or GB/T 1724, to ensure that the instrument meets the specifications. For special samples, such as corrosive or high-viscosity materials, the surface treatment or specialized material of the plate may need to be considered.