The number of meshes is the number of apertures, which is the number of apertures per square inch. The larger the mesh, the smaller the aperture. Generally speaking, the number of meshes × aperture (number of microns) = 15000. For example, the aperture of a 400 mesh shaker screen is about 38 microns; the aperture of a 500 mesh shaker screen is about 30 microns. Due to the problem of open porosity, that is, because of the difference in the thickness of the wire used when weaving the net, the standards of different countries are different. There are currently three types of American standards, British standards and Japanese standards. Among them, the British and the American are similar. Japanese is quite different. Our country uses the American standard, that is, it can be calculated with the formula given above.
It can be seen from this definition that the size of the mesh determines the size of the mesh aperture. The size of the mesh aperture determines the Dmax of the large particles of the meshed powder. Therefore, we can see that the 400 mesh polishing powder is entirely possible to be very fine, such as only 1-2 microns, and it is entirely possible that it is 10 microns or 20 microns. Because the pore size of the screen is about 38 microns. The D50 of our 400 mesh polishing powder is 20 microns.
Standard mesh number:
- Mesh refers to the number of apertures on the screen per square inch
50 mesh means that there are 50 apertures per square inch, and 500 mesh means 500. The higher the mesh number, the more apertures. In addition to the apertures of the mesh, it is also used to indicate the particle size of the particles that can pass through the mesh. The higher the mesh, the smaller the particle size. The standard mesh needs to be matched with a standard shale shaker for accurate determination.
- The particle size of the powder is called the particle size.
Because the particle shape is very complicated, there are usually several expression methods such as screening particle size, sedimentation particle size, equivalent volume particle size, and equivalent surface area particle size. The sieving particle size is the size of the mesh apertures through which the particles can pass through the mesh, expressed as the number of mesh apertures in a 1 inch (25.4mm) wide mesh, so it is called the “mesh number”. At present, there is no unified technical standard for powder particle size at home and abroad, and each enterprise has its own definition and expression method of particle size index. Screen specifications in different countries and industries have different standards, so the meaning of “mesh” is also difficult to unify. At present, international comparisons use the calculated diameter of particles of equivalent volume to express the particle size expressed in μm or mm.
Attachment: Conversion relationship: 1 μm = 1 micrometer = 0.001 millimeter. The empirical formula for the conversion between micrometer and mesh is as follows, the larger the mesh, the greater the error.