Mesh and Particle Size
1.[Mesh] is defined as the number of openings in one linear inch width of a screen. For example, a 50 mesh screen will have 50 openings in linear width per inch. The higher the mesh number, the smaller the screen openings. it is also used to indicate the particle size of the particles that can pass through the screen. The higher the mesh number, the smaller the particle size.
2.The size of the powder particles is called the particle size. The unit is expressed in μm or mm.
3.Due to different kinds of screens, the grid line diameters are different, the particle size corresponding to the same mesh is slightly different, and the standards established by countries and industries are also different. Currently, there is no uniform technical standards of the powder particle size in the world. so the meaning of “mesh” is also difficult to unify.
4.For the convenience of use, the relationship between granularity and mesh size, the rough conversion formula is:Particle size d (μm) = 15000 / mesh.
5.Commonly used particle size representation:
(1) The D value of the particle size distribution is marked as follows:
For example, the indication values are (D3, D50, D97). If a sample has D3 = 1 μm, it means that 3% of the mass particles are composed of particles smaller than 1 μm. D50 is also called the median diameter. If a sample has D50=5μm, it means that among the particles of all particle sizes constituting the sample, the mass of particles larger than 5μm accounts for 50%, and the mass of particles smaller than 5 μm also accounts for 50%. If a sample has D97 = 9 μm, it means that 97% of the mass particles are composed of particles smaller than 9 μm.
(2) Mesh size of product in noted with minus (-) and plus (+) sign as follows :
Mesh size with minus (-) sign indicate the particles can all pass through the mesh size. Mesh size with plus (+) sign indicate the particles can’t all pass through the mesh size. For example, a product identified as -100~200 mesh would contain particles that passed through a 100 mesh screen and can’t passed through a 200 mesh screen.
(3) The sieve residue ratio indication method:
The sieve residue refers to the manner in which the fineness of the powdery material is marked, and the mass ratio (%) of the powdery material remaining portion on the sieve after being sieved on the standard sieve. For example, if a powder is sieved with a 200-mesh sieve, the mass ratio under the sieve is 80%, and the mass ratio on the sieve surface is 20%, then we call the 20% powder as the sieve residue.